Michael Balz: Shells and Visions 303119263X, 9783031192630

Table of contents :
Preface
Contents
List of Figures
1 Introduction: Biographical Sketch
Abstract
1.1 Early Years
1.2 Entering Practice
1.3 First Shell Explorations
1.4 Freelance Collaborations
1.5 Individual Projects
1.6 Shells and Visions
1.7 Relationship with the International Association for Shell and Spatial Structures (IASS)
1.7.1 Tsuboi Award
1.7.2 IASS Structural Morphology Group
1.7.3 Executive Council and Advisory Board
References
2 Evolution/Organic Architecture
Abstract
2.1 Introduction: Organic Architecture
2.2 Urschalen (Primitive or Proto-Shells)
2.3 Collaboration with Heinz Isler
2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen: neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing: New Construction Methods)
2.4.1 Was sind menschliche Wohnformen? (How Would One Define Human Habitation?)
2.4.2 Was ist Geborgenheit? (What Is Security?)
2.4.3 Die Aufgabe (The Task)
2.4.4 Die Zukunft (The Future)
2.4.5 Eine Bauweise heute (Construction Today)
2.4.6 Die Entwurfsmethode (Design Method)
2.4.7 Der Übergang zur Natur (Link to the Natural Environment)
2.4.8 Der Eingang (The Entrance)
2.4.9 Eine kleine Landschaft zum Wohnen! (A Small Landscape for Living!)
2.4.10 Die geschlossene Ruhezone (The Closed Rest Zone)
2.4.11 Die praktischer Arbeitsraum (The Practical Workspace)
2.4.12 Minimaler Materialaufwand (Minimal Material Consumption)
2.5 Living Shell Projects
2.5.1 Private Client, 1968
2.5.2 House for Heinz and Maria Isler (1972–73)
2.5.3 Bio-segment
2.5.4 Isler ‘Bubble System AG’
2.6 A Future for Living Shells?
References
3 Built Shells
Abstract
3.1 Inspiration
3.2 Zuschauer Halle/Kuppel (Auditorium), Theater unter den Kuppeln (Theatre under the Domes), Stetten auf den Fildern, Near Stuttgart (1976)
3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78)
3.3.1 Form-Finding of the Shell
3.3.2 Shell Construction
3.3.3 Architectural and Aesthetic Considerations
3.4 Ballettsaal (Ballet Salon), Stetten (1979)
3.5 Musical-Saal (Musical Salon), Stetten (1988–1989)
3.6 Europa-Park, in Rust (1992): Entrance Canopies
3.7 Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992)
3.8 Reflection
References
4 Balz House, Stetten auf den Fildern Leinfelden-Echterdingen, Near Stuttgart (1980)
Abstract
4.1 Introduction
4.2 First Encounter
4.3 Finding the Form
4.4 Accommodation
4.5 Construction: Forming the Shell
4.6 The Interior
4.7 Keeping It Warm: The Thermal System
4.8 Thermal Comfort
4.9 Durability
4.10 Living in the Balz House
4.11 Architectural and Social Significance
4.12 Embodied Energy
4.13 Operational Energy
4.14 Final Thoughts…
References
5 Competitions
Abstract
5.1 Introduction
5.2 Evangelical Lutheran Church, Heilbronn (1967)
5.3 Haus der Geschichte der Bundesrepublik Deutschland (German National Museum of Contemporary History), Bonn (1985)
5.3.1 Introduction
5.3.2 Shell Roofs
5.3.3 Internal Planning
5.3.4 Appreciation
5.4 Badezentrum Sindelfingen (Thermal Baths), Böblingen (1983)
5.4.1 Introduction
5.4.2 Thermal Baths
5.4.3 Shell Roof
5.5 German Pavilion, Expo’2000, Hanover (1997)
5.5.1 Introduction
5.5.2 Proposed Pavilion
5.5.3 Internal Planning
5.5.4 Aesthetic Considerations
5.6 Hegau Auto Rast: Motorway Service Area, Near Engen (1997)
5.6.1 Introduction
5.6.2 Competition Entry
5.7 Epilogue
References
6 Unrealized Shell Projects
Abstract
6.1 Introduction
6.2 Tropicana, Lucerne (1979)
6.3 Atelier and Office Building for Willi Bösiger AG Langenthal, Switzerland (1986)
6.4 Wallwitzhafen Dessau: Freizeit Park (Leisure Park) (1992–93)
6.5 Thane, Near Mumbai, India: Modular Dwelling Units (1994) and Cosmo Ville, Amenities Centre (1995)
6.5.1 Flower House, Modular Dwelling
6.5.2 Cosmo Ville, Thane, India (1995)
6.6 Heliopolis University, Shell of Peace, Cairo, Egypt (2016)
6.7 Skateboarding Club (2016)
6.8 Street Bar, Stuttgart (2017)
6.9 Why Have These Projects Not Been Built?
References
7 Urban Space Structures
Abstract
7.1 Introduction
7.2 Project ‘Stuttgart 2000’ (1965–1982)
7.3 Cityscape Visions
7.4 Building Today
7.5 Opportunities for a New Construction Industry
7.6 Space Above the Land
7.7 Housing Units for Spatial Urban Structures
7.8 Supporting Bridge Structures
7.9 Feasibility of the Megastructures
7.10 The Spatial City
7.11 Concerning the Responsibility of the Designers
7.12 Is This the Future for an Urbanized Society?
References
8 Timeline and Postscript
Abstract
8.1 Timeline
8.2 Postscript
8.3 Not Luxurious Expensive Dreams…
8.4 There Are No Limits
References
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Bib1
Index

Citation preview

John Chilton

Michael Balz Shells and Visions

Michael Balz

John Chilton

Michael Balz Shells and Visions

123

John Chilton Emeritus Professor of Architecture & Tectonics Department of Architecture and Built Environment University of Nottingham Nottingham, UK

ISBN 978-3-031-19263-0 ISBN 978-3-031-19264-7 https://doi.org/10.1007/978-3-031-19264-7

(eBook)

© Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cover image: © The Balz House, Stetten (Reproduced from photograph by Michael Balz with permission from Michael Balz) This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

This book is dedicated to the memory of my mother Dorothy ‘Dorrie’ Lilian Chilton, née Lewis. She was an avid reader, mainly of detective and murder mysteries. Nevertheless, she had read all of my previous books, although they were focused on architecture and structural engineering. She declared them easy to read and understandable even for the non-technical reader. Sadly, she succumbed to COVID-19, in December 2020, at the age of 100, before she could read this volume.

Preface

I did not know it at the time, but the seed for this book was planted in a hotel corridor in Copenhagen thirty years ago while I was attending the annual symposium of the International Association for Shell and Spatial Structures (IASS). This was the instant when my connection to and friendship with Michael Balz and his family began. Our initial encounter was fortuitous —purely by chance we had adjacent rooms in the same hotel. One morning he and his wife Eva happened to come out of their room at the same time as I did. Realizing that we were both attending the IASS symposium, we introduced ourselves and sat together for breakfast, as we then did on following days. It was during our conversations over breakfast that I first learnt that Michael and Eva Balz lived (and still live) in an ‘UFO-like’ house in Stetten, near Stuttgart. Our second meeting was not until about 18 months later, in May 1993, when I attended a technical meeting in Stuttgart. Recalling that the Balz House was located near to Stuttgart Airport, I looked out for it as my flight from Birmingham was landing. Although the weather was dull and cloudy, I managed to identify the house and neighbouring shells through a small break in the low clouds. On landing I called Michael, and he very kindly invited me to dinner that evening. That visit introduced me to the wonderful interior of the Balz House and the free-form shells of the Theater unter den Kuppeln. During the symposium in Copenhagen, we had both participated in the inaugural meeting of the IASS Working Group 15: Structural Morphology, known as the Structural Morphology Group (SMG). This led to our third meeting, which occurred at the second SMG seminar, held in Stuttgart in 1994. Activities were split between two sites, with the first day’s events— relaxed ‘performances’ rather than formal presentations—taking place in Stetten, in and around the shells designed by Michael Balz with Heinz Isler as engineer. At this event, I first met Michael and Eva’s son Markus, who was operating the video camera recording the proceedings. My friendship with Markus flourished later, when we worked closely together as members of TensiNet, an international research network on tensile structures. Since 1994, Michael and I have met at many symposia and IASS meetings. We liaised about his collaboration with Heinz Isler when I wrote my book about the engineer—Heinz Isler: The Engineer’s Contribution to Contemporary Architecture—in 1999–2000. In 2010, I had the opportunity to visit the spectacular outdoor theatre shell in Grötzingen with him. Hence, when, in 2018, the idea was floated for a book about Michael’s thin concrete shells and visions for urban spatial structures, I jumped at the chance to show this from the architect’s point of view. In June 2018, I spent three days at the Balz House talking to Michael and collecting information about his work. I produced a draft outline and a sample chapter and submitted my proposal to Springer. This received positive feedback from the reviewers, and the contract was signed in the summer of 2019. We then arranged for me to stay at the Balz House again for three days in late August 2019. However, unfortunately, Michael was taken seriously ill while on holiday, just a few days before my visit, and our meeting was cancelled. He had recovered by early October, and we met at the IASS symposium in Barcelona. There we made plans to meet in Stetten in early 2020, to select and scan images for inclusion in the book, but my personal circumstances—a minor operation that made travel problematic—prevented this. vii

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Preface

Then the COVID-19 pandemic struck, and travel was out of the question. Progress slowed as image selection and scanning had to be negotiated remotely. Further illness and the impacts of COVID-19 restrictions and infection caused additional delays, but the manuscript finally emerged in October 2021 with a revised version in July 2022. Nottingham, UK

John Chilton

Acknowledgments

First and foremost, I give my special thanks to my wife Gloria Llanos for her support and continued patience during the creation of this book, the writing of which has diverted me from other important projects. I would also like to express my gratitude to Michael and Eva Balz for their friendship, which extends over 30 years, and their warm and generous hospitality when welcoming me to stay in their home, in June 2018. I spent three very enjoyable days in and around the Stetten shells, perusing a small exhibition of Michael’s projects that he had prepared in advance, discussing the projects with him in detail and looking at drawings and photographs that were potentially available for inclusion in the book. My thanks also goes to Michael’s children: to Markus for our COVID-restricted online video meetings—usually on Friday evenings accompanied by a cold beer or glass of wine— where he guided me through his father’s responses to my more detailed questions and requests for more information on projects; to Angelika for helping her father to find and scan numerous drawings and photographs from his archive, which I had identified for inclusion in the book; and to Johannes for participating in the group online video discussion I had with all three on 1 May 2020. I would also like to thank Michael’s brother Prof. Dr. phil. Dr. theol. Heinrich Balz, who contributed to the discussion during my interview with Michael on 5 June 2018 and also read and commented on the draft manuscript. Although the majority of illustrations are from Michael Balz’s own archive or my own photographs, I would like to thank all who have granted permissions for their inclusion as noted in the captions—Angelika Balz, Eva Balz, Johannes Balz, Markus Balz, Michael Balz, Europa-Park, Naturtheater Grötzingen e.V., Theater unter den Kuppeln, Walter and Werner Steck. In particular I would like to mention Peter Kofel, for granting permission for content related to Heinz Isler and Prof. Johannes Fritz for granting permission for the inclusion of his rendered drawing of the competition entry for the Haus der Geschichte der Bundesrepublik Deutschland (German National Museum of Contemporary History), Bonn (1985). Also, to Theresa Nettekoven for allowing me to reproduce figures from her Masters thesis, which examined the structural feasibility of Michael Balz’s visionary architectural urban design concepts and Henning Dürr for permission to include his computer renderings of the same. Last but not least, I would like to thank Springer Nature for commissioning the book and the editorial team for their assistance in its production: Oliver Jackson, Editor (Engineering) Springer Ambrose Berkumans, Project coordinator, Books Production

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Contents

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2 Evolution/Organic Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Introduction: Organic Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Urschalen (Primitive or Proto-Shells) . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Collaboration with Heinz Isler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen: neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing: New Construction Methods) . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1 Was sind menschliche Wohnformen? (How Would One Define Human Habitation?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2 Was ist Geborgenheit? (What Is Security?) . . . . . . . . . . . . . . . 2.4.3 Die Aufgabe (The Task) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.4 Die Zukunft (The Future) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.5 Eine Bauweise heute (Construction Today) . . . . . . . . . . . . . . . 2.4.6 Die Entwurfsmethode (Design Method) . . . . . . . . . . . . . . . . . 2.4.7 Der Übergang zur Natur (Link to the Natural Environment) . . . 2.4.8 Der Eingang (The Entrance) . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.9 Eine kleine Landschaft zum Wohnen! (A Small Landscape for Living!) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.10 Die geschlossene Ruhezone (The Closed Rest Zone) . . . . . . . . 2.4.11 Die praktischer Arbeitsraum (The Practical Workspace) . . . . . . 2.4.12 Minimaler Materialaufwand (Minimal Material Consumption) . 2.5 Living Shell Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1 Private Client, 1968 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.2 House for Heinz and Maria Isler (1972–73) . . . . . . . . . . . . . . 2.5.3 Bio-segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.4 Isler ‘Bubble System AG’ . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 A Future for Living Shells? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 Introduction: Biographical Sketch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Early Years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Entering Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 First Shell Explorations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Freelance Collaborations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Individual Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Shells and Visions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 Relationship with the International Association for Shell and Spatial Structures (IASS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7.1 Tsuboi Award . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7.2 IASS Structural Morphology Group . . . . . . . . . . . . . . . . . . 1.7.3 Executive Council and Advisory Board . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3 Built Shells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Inspiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Zuschauer Halle/Kuppel (Auditorium), Theater unter den Kuppeln (Theatre under the Domes), Stetten auf den Fildern, Near Stuttgart (1976) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78) . . . . . . . . . 3.3.1 Form-Finding of the Shell . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Shell Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 Architectural and Aesthetic Considerations . . . . . . . . . . . 3.4 Ballettsaal (Ballet Salon), Stetten (1979) . . . . . . . . . . . . . . . . . . . 3.5 Musical-Saal (Musical Salon), Stetten (1988–1989) . . . . . . . . . . . 3.6 Europa-Park, in Rust (1992): Entrance Canopies . . . . . . . . . . . . . 3.7 Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8 Reflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Balz House, Stetten auf den Fildern Leinfelden-Echterdingen, Near Stuttgart (1980) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 First Encounter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Finding the Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Accommodation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Construction: Forming the Shell . . . . . . . . . . . . . . . . . . . . 4.6 The Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Keeping It Warm: The Thermal System . . . . . . . . . . . . . . 4.8 Thermal Comfort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10 Living in the Balz House . . . . . . . . . . . . . . . . . . . . . . . . . 4.11 Architectural and Social Significance . . . . . . . . . . . . . . . . . 4.12 Embodied Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.13 Operational Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.14 Final Thoughts… . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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5 Competitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Evangelical Lutheran Church, Heilbronn (1967) . . . . . . . . . . . . . . . . 5.3 Haus der Geschichte der Bundesrepublik Deutschland (German National Museum of Contemporary History), Bonn (1985) . 5.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Shell Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.3 Internal Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.4 Appreciation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Badezentrum Sindelfingen (Thermal Baths), Böblingen (1983) . . . . . 5.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.2 Thermal Baths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.3 Shell Roof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 German Pavilion, Expo’2000, Hanover (1997) . . . . . . . . . . . . . . . . . 5.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.2 Proposed Pavilion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.3 Internal Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.4 Aesthetic Considerations . . . . . . . . . . . . . . . . . . . . . . . . . .

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5.6

Hegau Auto Rast: Motorway Service Area, 5.6.1 Introduction . . . . . . . . . . . . . . . . . 5.6.2 Competition Entry . . . . . . . . . . . . 5.7 Epilogue . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Near Engen (1997) . . . . . . . . . 127 . . . . . . . . . . . . . . . . . . . . . . . . 127 . . . . . . . . . . . . . . . . . . . . . . . . 127 . . . . . . . . . . . . . . . . . . . . . . . . 129 . . . . . . . . . . . . . . . . . . . . . . . . 134 . . . . . . . . . . 135 . . . . . . . . . . 135 . . . . . . . . . . 135

6 Unrealized Shell Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Tropicana, Lucerne (1979) . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Atelier and Office Building for Willi Bösiger AG Langenthal, Switzerland (1986) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Wallwitzhafen Dessau: Freizeit Park (Leisure Park) (1992–93) 6.5 Thane, Near Mumbai, India: Modular Dwelling Units (1994) and Cosmo Ville, Amenities Centre (1995) . . . . . . . . . . . . . . 6.5.1 Flower House, Modular Dwelling . . . . . . . . . . . . . . . 6.5.2 Cosmo Ville, Thane, India (1995) . . . . . . . . . . . . . . 6.6 Heliopolis University, Shell of Peace, Cairo, Egypt (2016) . . . 6.7 Skateboarding Club (2016) . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8 Street Bar, Stuttgart (2017) . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 Why Have These Projects Not Been Built? . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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7 Urban Space Structures . . . . . . . . . . . . . . . . . . . . . 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Project ‘Stuttgart 2000’ (1965–1982) . . . . . . . . 7.3 Cityscape Visions . . . . . . . . . . . . . . . . . . . . . 7.4 Building Today . . . . . . . . . . . . . . . . . . . . . . . 7.5 Opportunities for a New Construction Industry 7.6 Space Above the Land . . . . . . . . . . . . . . . . . . 7.7 Housing Units for Spatial Urban Structures . . . 7.8 Supporting Bridge Structures . . . . . . . . . . . . . 7.9 Feasibility of the Megastructures . . . . . . . . . . . 7.10 The Spatial City . . . . . . . . . . . . . . . . . . . . . . . 7.11 Concerning the Responsibility of the Designers 7.12 Is This the Future for an Urbanized Society? . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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8 Timeline and Postscript . . . . . 8.1 Timeline . . . . . . . . . . . . 8.2 Postscript . . . . . . . . . . . . 8.3 Not Luxurious Expensive 8.4 There Are No Limits . . . References . . . . . . . . . . . . . . . .

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Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

List of Figures

Fig. 1.1

Fig. 1.2

Fig. 1.3

Fig. 1.4

Fig. 1.5

Fig. 1.6

Fig. 1.7 Fig. 1.8

Fig. 1.9

Fig. 2.1

Fig. 2.2

Michael Balz and his wife Eva who he met when she was visiting his mother’s studio for a pottery class. Reproduced from photograph by Michael Balz with permission from Michael and Eva Balz . . . . . . . . . Sculpture of the infant Michael by his father sculptor Ernst Balz. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External and internal views of the refurbished glazing of the tear-dropshaped skylight, Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart. Photograph (left) John Chilton; (right) reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Competition winning design for a retirement home village in Wangen/ Allgäu. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Planetarium Stuttgart (1974) with supporting external trussed-grid frame of stainless steel tubes. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . Entry for an architectural competition “Stuttgart 2000” high-density urban residences in “dwelling trees”, based on bridge building principles. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single and multiple family units in Zell am Neckar. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . Section (top) and elevation (bottom) of design for villa in Birkenfeld. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IASS Tsuboi Award received by Michael Balz in 1991. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Natural forms used by Michael Balz to inform his design of free-form shells: a precious wentletrap, Epitonium scalare. Photograph John Chilton. b Exterior and interior structure of chambered nautilus, Nautilus pompilius. Photograph John Chilton. c Lady’s-slipper orchid, Cypripedium calceolus. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . Urschalen: development of two alternative prototype shells for living showing—from left to right: the initial cast form; proposed widow and door openings; shell with cut-outs; proposed internal planning. Reproduced from photographs by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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xvi

Fig. 2.3

Fig. 2.4

Fig. 2.5

Fig. 2.6

Fig. 2.7

Fig. 2.8

Fig. 2.9

Fig. 2.10

Fig. 2.11

Fig. 2.12

Fig. 2.13

Fig. 2.14

Fig. 2.15

List of Figures

Alternative proposals for foundation systems for the pneumatic-formed shells. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Examples of model Urschalen pneumatically formed shell houses photographed by Michael Balz while visiting Heinz Isler in summer 1967 on the bank of the River Emme, close to Isler’s office. Reproduced from photographs by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front cover of the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing—New Construction Methods). Photograph John Chilton with permission from Michael Balz and the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Michael Balz’s sketches showing that the human anatomy favours movement along curves. The layout shown is that of the Balz House described in detail in Chap. 4. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . Michael Balz’s sketches showing how rounded forms enhance feelings of security and social interaction. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . One of the model, curved-form, habitable shells illustrated in the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Two- to four-person shell house, of 95 m2 in plan from the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Larger five- or six-person shell house, of 125 m2 in plan from the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sketch section through proposed living shell dwelling for a private client, in 1968. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground floor plan of one of the alternative house proposals for Heinz and Maria Isler at Lyssachschachen, near Burgdorf, Switzerland, 1972. Reproduced from drawing by Michael Balz with permission from Michael Balz and the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . Upper floor plan of the same house proposal for Heinz and Maria Isler at Lyssachschachen, near Burgdorf, Switzerland, 1972. Reproduced from drawing by Michael Balz with permission from Michael Balz and the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Michael Balz’s model of the preferred scheme for Heinz and Maria Isler’s house at Lyssachschachen, near Burgdorf. Reproduced from photograph by Michael Balz with permission from Michael Balz and the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ‘Bio-segment’ system of dwelling or living cells proposed by Michael Balz in January 1971. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Fig. 2.16

Fig. 2.17

Fig. 2.18

Fig. 3.1

Fig. 3.2

Fig. 3.3

Fig. 3.4

Fig. 3.5

Fig. 3.6 Fig. 3.7

Fig. 3.8

Fig. 3.9 Fig. 3.10

Fig. 3.11

Fig. 3.12 Fig. 3.13

Alternative combinations and extension of the modular ‘bio-segment’ system. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alternative ‘bio-segment’ system of dwelling or living shells for a warm climate. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alternative two-storey ‘bio-segment’ system of dwelling or living shells. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site plan showing the complex of five Balz/Isler shells at Stetten auf den Fildern, near Stuttgart, as proposed in 1980. The basement plan of the ballet salon is shown to the right. The shell shown top right was never constructed. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a Plan view; and b elevational view from north-west of the architectural model of the Stetten site, excluding the Balz House. Reproduced from photographs by Michael Balz with permission from Michael Balz . . . a, b Gypsum plaster casts of the hanging models used to explore the potential geometry of the Theater unter den Kuppeln, Stetten, photographed in Heinz Isler’s studio. Photographs John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Main timber arched profiles being installed to define the shell form of the Theater unter den Kuppeln shell, Stetten. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . Flowing arch form of the Theater unter den Kuppeln shell, Stetten, as seen from the performance space. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan of the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . Front elevation and centre line section of the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Naturtheater, Grötzingen shell blends into the surrounding woodland. Photograph John Chilton with permission from Michael Balz and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Initial wireframe model for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family . . . . . Plan template for producing hanging membrane models for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plaster cast from one of the exploratory hanging membrane models for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan view of plaster cast shown in Fig. 3.11. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . Arrangement of the foundations and ground beams for the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Fig. 3.14

Fig. 3.15

Fig. 3.16

Fig. 3.17

Fig. 3.18

Fig. 3.19

Fig. 3.20

Fig. 3.21

Fig. 3.22

Fig. 3.23

Fig. 3.24

List of Figures

Lightweight adjustable scaffolding supports the shell falsework and formwork. Michael Balz (facing camera) and Heinz Isler are in discussion in the foreground in February 1978. Reproduced from photograph by Michael Balz with permission from Michael Balz, the Isler family and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . Curved primary beams assembled from discrete sawn profiled sections follow the geometry measured along grid lines on the hanging membrane models for the Naturtheater, Grötzingen shell. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heinz Isler is the central figure carrying out a site inspection of the Naturtheater, Grötzingen shell falsework. Reproduced from photograph by Michael Balz with permission from Michael Balz, the Isler family and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flexible timber laths at approximately 250 mm centres laid across the primary grid beams to generate the double-curved surface derived from the hanging membrane models for the Naturtheater, Grötzingen shell. Note the continuous boarding near the support in the foreground where a fair-faced finish is required. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen . . . Formwork and reinforcement at the north-west shell base. Note the areas at the shell edge and the inclined leg where no insulation slabs have been placed, thus forming a wide but shallow edge stiffening element. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen . . . . . . . . . . . Placing of the shell concrete. Note the heavy steel reinforcement in the slightly thickened shell edge. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen . . . Elegant slender form of the Naturtheater, Grötzingen shell shortly after completion. The shell is actually thinner than it appears because there is a small non-structural lip or upstand at the edges to direct rainwater off the shell. The maximum span to minimum thickness ratio is 467:1. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . . Architect Michael Balz at the thin edge of the Naturtheater, Grötzingen shell indicating the small raised lip provided to channel rainwater to the drainage system at the supports. Note the natural surface patina of moss and lichens. Photograph John Chilton with permission of Michael Balz and Naturtheater, Grötzingen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unobtrusive rings of auditorium lighting contrast with the array of spotlights, which tend to intrude and slightly detract from the clean curve of the 42-m span arch of the front shell edge. Photograph John Chilton with permission of Michael Balz and Naturtheater, Grötzingen . . . Interior of the Ballettsaal (Ballet Salon) shell, Stetten auf den Fildern. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . Model used to precisely determine the Ballettsaal shell geometry showing the grid lines along which Heinz Isler measured the coordinates of points on the plaster cast and the perimeter of the proposed shell that has been drawn on its surface. Photograph John Chilton with permission of the Isler family . . . . . . . . . . . . . . . . . . . . . . . .

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xix

Fig. 3.25

Fig. 3.26

Fig. 3.27

Fig. 3.28

Fig. 3.29

Fig. 3.30

Fig. 3.31

Fig. 3.32

Fig. 3.33

Fig. 3.34

Fig. 3.35 Fig. 3.36

1:50 scale plan showing the setting out geometry for the edge profiles of the Ballettsaal shell—Heinz Isler’s drawing SB321/22 dated 22 March 1979. The relationship of the insulation used as sacrificial shuttering and the shell can be seen in the sections. Reproduced from drawing by Heinz Isler in the possession of Michael Balz, with permission of Michael Balz and the Isler family . . . . . . . . . . . . . . . . . Heights for shell support (Höhe für Schalenschalung) on Heinz Isler’s drawing SB452/28 dated 21 March 1989. These are for the main body of the mirrored version of the same geometry, as used for the MusicalSaal, constructed in 1988–1989. Note the contours at 0.5 m intervals sketched approximately in pencil. Reproduced from drawing by Heinz Isler in the possession of Michael Balz, with permission of Michael Balz and the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Profiled binder beams and draped flexible laths define the Ballettsaal shell geometry. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . Shell preparation for concreting with insulation slabs used as permanent shuttering in place and the bottom layer of steel reinforcement in the edge sections. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . General placement of steel reinforcement in two layers over the insulation slabs. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . Different coloured zones reveal the progress as concrete is gradually placed across the shell from the individual bases towards the long base edge. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . Hand tool finishing of the sprayed concrete on the long base steepest face of the Ballettsaal shell. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Extreme thinness, typically just 80 mm, and sculptural qualities of the shell can be fully appreciated before the façades are installed. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . Sympathetic north façade glazing of the Ballettsaal shell, set back from the free edge as seen from the Balz House. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Over the last 40 years the surface has acquired a patina of lichens and blends effortlessly into the surrounding vegetation. Photograph John Chilton with permission of Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Final plan of the Stetten cultural centre. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Musical-Saal shell, viewed from the rear of the Theater unter den Kuppeln, with the linking cafeteria to the right. Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Fig. 3.37

Fig. 3.38

Fig. 3.39

Fig. 3.40

Fig. 3.41

Fig. 3.42

Fig. 3.43

Fig. 3.44

Fig. 3.45

Fig. 3.46 Fig. 3.47

Fig. 4.1

Fig. 4.2

Fig. 4.3

List of Figures

Interior view of the Musical-Saal shell shows the organic sweep of the insulated surface which conceals the upper frame of the metal-framed glazing. Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cafeteria/foyer building with organic tree-like columns linking the three shells. The Musical-Saal shell is just visible (left) and theatre shell (right). Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internal view of the foyer with the theatre shell behind. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scale model of entrance canopy for Europa-Park developed by Michael Balz’s son Markus Balz. Photograph John Chilton with permission from Markus Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reusable timber formwork with “…reinforcement […] woven over the wooden formwork using a four-edge system which enables an optimal adaption to the organic shape.” (Balz 2011) for one of the entrance canopy shells for the Eisstadion (ice stadium) in the Greek themed area at Europa-Park. Reproduced from photograph by Michael Balz with permission from Michael Balz and Europa-Park . . . . . . . . . . . . . . . . . Completed entrance canopy shell for Europa-Park. Reproduced from photograph by Michael Balz with permission from Michael Balz and Europa-Park . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shell design for an exhibition space to enclose a replica of the Soviet/ Russian space station Mir, at Europa-Park. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . Alternative proposal for an exhibition space to enclose a replica of the Soviet/Russian space station Mir, at Europa-Park. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . Partially prefabricated prototype carport, 6 m  6 m, in collaboration with Willi Bösiger SA: (top) development model; (middle and bottom) outside the company’s offices in Langenthal, Switzerland. Photographs top and middle Reproduced from photographs by Michael Balz with permission from Michael Balz; bottom photograph: John Chilton . . . . Precast base element of the partially prefabricated prototype carport. Photograph John Chilton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Proposals for modular low-cost housing using thermoformed insulated shells. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Balz House viewed from the north-west. The shell appears to hover above the ground. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Template following the proposed Balz House floor plan at 1:20 scale used to produce an inflated PVC membrane form by air pressure from below and heat applied from above to increase its elasticity. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concept model of the Balz House derived from modelling with an inflated PVC membrane at 1:20 scale. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . .

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List of Figures

xxi

Fig. 4.4

Fig. 4.5

Fig. 4.6

Fig. 4.7

Fig. 4.8

Fig. 4.9

Fig. 4.10

Fig. 4.11

Fig. 4.12

Fig. 4.13

Fig. 4.14

Fig. 4.15

Fig. 4.16

Fig. 4.17

Fig. 4.18

Plan of the Balz House, Stetten, showing: A: main living/relaxation area; B: dining area; C: kitchen and breakfast bar; D: master bedroom; E: bathing grotto; F: fireplace/chimney; G: external terrace. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . Long section through the Balz House, Stetten, showing the additional storage/viewing platform above the kitchen (centre), accessed by a ladder, and more conventional accommodation below. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . Sketches showing proposed layout of individual steel bar (rather than welded mesh) reinforcement following the curvature of the shell. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel reinforcement formed over curved timber beams and the steel window frame to the left. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . (left) Lightweight mesh is attached to the main steel reinforcement and seen in close up in the background (right). Reproduced from photographs by Michael Balz with permission from Michael, Eva, Johannes and Angelika Balz, Walter and Werner Steck . . . . . . . . . . . . . . . Compaction and hand-finishing of the low-slump concrete placed on the lower shell, in 1979. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Placing by skip suspended from a tower crane and compaction of the upper shell. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organic form of kitchen, breakfast bar, upper platform and fireplace (to right) all moulded from concrete. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . View of interior of the upper shell from the upper platform with original bespoke furnishing covered with purple fabric. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Custom-built shelving and pendant lamp support arm by Michael Balz to the left. Late afternoon sun fills the seating area. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Schematic post-construction drawing showing details of the solar thermal energy capture and low-temperature heating systems inserted in the concrete elements of the shell, deck, floors, walls and other thermally massive interior features. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . Twenty-mm-diameter polyethylene pipes are looped through the shell to capture heat from the concrete warmed by the sun. Shown here during construction before adding the outer concrete layer. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . Through heating pipes embedded in the walls and base the bathing grotto is effectively warmed by the sun! Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Metal-framed glazing is fully concealed externally by the shell at their junction and by insulation internally. Photograph John Chilton with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External surface of the shell in June 2018 is still well preserved after almost 40 years. Photograph John Chilton with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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xxii

Fig. 4.19

Fig. 4.20

Fig. 4.21 Fig. 4.22

Fig. 4.23

Fig. 4.24

Fig. 5.1

Fig. 5.2

Fig. 5.3 Fig. 5.4

Fig. 5.5

Fig. 5.6 Fig. 5.7

Fig. 5.8

Fig. 5.9

List of Figures

Upper platform used as a space for quiet relaxation has a panoramic view of the open living room below, to the right. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Michael Balz on the west-facing roof terrace adjacent to the sheltered external dining space in June 2018. Photograph John Chilton with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The extensive external terrace on the south side of the shell—ideal for parties. Photograph John Chilton with permission from Michael Balz . . . . Distinctive organic architecture of the Balz House viewed from the south-west. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . South elevation of the Balz House showing kitchen and platform over. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Snow clinging to the shell surface of the Balz House reveals the high quality of the insulated building envelope. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Preliminary sketch of church with side rooms, dated 8th October 1967, for the competition entry for an Evangelical Lutheran church, in Heilbronn. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preliminary sketch of sacred building in shell construction, dated 8th October 1967, for the competition entry for an Evangelical Lutheran church, in Heilbronn. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan of final competition entry. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . Plan view of presentation model for final competition entry. Note the piercing of the roof shell that allows the altar to be illuminated by light reflected downward from the curving tower shell. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Model of the final competition entry showing the relationship of the tower to the main shell and linking of ancillary shells with the flatroofed terrace. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Orchid flower inspiration for the tower form. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Model of the final competition entry against a background of wooded landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Model of proposed shell roofs for the German National Museum of Contemporary History, Bonn, arranged like petals of a flower around a central courtyard. The shadows reveal the curvature of the forms. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan of competition entry for proposed German National Museum of Contemporary History, Bonn showing relationship of shell roofs (boundaries shaded yellow) to mezzanine and intermediate floors (red and green, respectively). The roof glazing and inclined façade glazing are shaded blue. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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List of Figures

xxiii

Fig. 5.10

Fig. 5.11

Fig. 5.12

Fig. 5.13

Fig. 5.14

Fig. 5.15

Fig. 5.16

Fig. 5.17

Fig. 5.18

Fig. 5.19

Fig. 5.20

Fig. 5.21

Fig. 5.22

North-east elevation (top) and sections B–B (middle) and A–A (bottom) as shown in Fig. 5.9 of the competition entry for proposed German National Museum of Contemporary History, Bonn, show the relationship between the thin shells and the stepped floor plans. Reproduced from rendered drawing by Johannes Fritz with permission from Johannes Fritz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cut-away view of model of the proposed German National Museum of Contemporary History, Bonn, with the shell over the main entrance removed. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . View from the north-east of the physical model of the proposed German National Museum of Contemporary History, Bonn, showing the largest (entrance) shell within the landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . View from the south-west of the physical model of the proposed German National Museum of Contemporary History, Bonn, showing how the shells group round the courtyard and within the landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site plan for the proposed thermal baths at Sindelfingen, Böblingen. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . View of model with the roof shell form-found by hanging membrane. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . View of model with the roof shell form-found by hanging membrane. The lenticular glazed opening can be seen between the larger shell surface and the triangular shell over the main entrance. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . View of model from east showing the surrounding terraced roof, the merged shell base and lenticular rooflight to the right. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . Location plan showing Michael Balz’s proposal for the German Pavilion, at Expo’2000, in Hanover, overlooking the Expo-Plaza. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Model of the proposal for the German Pavilion, at Expo’2000, in Hanover, with shell forms derived using hanging membranes. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross-section north/south (top) and long-section west/east (bottom) of the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Model showing the organically formed floors of the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . a Basement (top); b ground/entrance (middle); c first (bottom); d second (top); e third (middle); and f mezzanine (bottom) floor plans for the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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xxiv

Fig. 5.23

Fig. 5.24 Fig. 5.25

Fig. 6.1

Fig. 6.2

Fig. 6.3

Fig. 6.4

Fig. 6.5

Fig. 6.6

Fig. 6.7

Fig. 6.8

Fig. 6.9

Fig. 6.10

Fig. 6.11

List of Figures

Model for the proposed Hegau Auto Rast, with inclined central shell. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan view of model for the proposed Hegau Auto Rast. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . a North-east (top); b south-west (middle); and c north-west (bottom) elevations of the Hegau Auto Rast shells. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Alternative sketch proposals of shell roofs for the Tropicana, Lucerne. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detailed sketch proposal for shell roof for the Tropicana, Lucerne. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Initial form-finding hanging fabric membrane model by Michael Balz, of the proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . Concept model of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Photograph John Chilton with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Initial wireframe model for Willi Bösiger AG studio and office building encountered in Heinz Isler’s studio in 2011. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heinz Isler’s exploratory model form-found with suspended woven fabric for Willi Bösiger AG studio and office building. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . Baseboard used to create the precise hanging form-finding shell models for Willi Bösiger AG studio and office building. The hexagonal zone, bounded by the thin wooden strips, can be released and dropped after a plaster-covered latex membrane has been stretched between the large wooden blocks. Photograph John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Precise plaster models produced by Heinz Isler’s hanging membrane method for Willi Bösiger AG studio and office building a showing locations of profile measurement points (circled); and b plan view with thrust lines from the bases projected across the surface. Photographs John Chilton with permission from the Isler family . . . . . . . . . . . . . . . . . . Ground floor plan dated, 4th April 1986, of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . Section of proposed atelier and office building, dated 9th July 1989, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . West (top) and south (bottom) elevations, dated 9th July 1989, of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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List of Figures

xxv

Fig. 6.12

Fig. 6.13

Fig. 6.14

Fig. 6.15

Fig. 6.16

Fig. 6.17

Fig. 6.18

Fig. 6.19

Fig. 6.20

Fig. 6.21 Fig. 6.22

Fig. 6.23

Fig. 6.24

Fig. 6.25

Fig. 6.26

Site plan of the proposal for a leisure park development in Wallwitzhafen, Dessau. From left to right: ice/roller skating rink; beer garden; indoor and outdoor swimming pools; hotel; viewing tower; and indoor tennis courts. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . Sketch of the proposed conference centre and Elbhotel at the leisure park development in Wallwitzhafen, Dessau. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . Panoramic sketch of an alternative scheme for a leisure park development in Wallwitzhafen, Dessau, showing diversity of proposed shells. Reproduced from drawing by Buro Isler with permission from the Isler family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sketch of the proposed Flower House 1, Thane, near Mumbai, India. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Floor plan and section of the proposed modular prefabricated Flower House 2, Thane, India, dated 12th December 1994. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . Site layout plan of Cosmo Ville development, Thane, India, dated 12th March 1994. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ‘Bio-segment’ housing proposed for Cosmo Ville, Thane, India. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Proposed meditation temple, dedicated to the Hindu god Surya, for Cosmo Ville development, Thane, India, dated 8th January 1995. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site plan and elevation of the Cosmo Ville, amenities centre, Thane, India—composed of four free-form shells around a lake. Reproduced from drawing by Michael Balz with permission from Michael Balz . . Heliopolis University, Shell of Peace. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Crossed hands—inspiration for the plan of the Heliopolis University, Shell of Peace. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site plan of the Heliopolis University, Shell of Peace with open forum (centre), enclosed conference hall (right) and core centre (left). Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . West (upper) and north (lower) elevations of the Shell of Peace, Heliopolis University, with open forum (centre), enclosed conference hall (right) and core centre (left). Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . Basement plan of the Shell of Peace, Heliopolis University, showing the link between forum, conference hall and core centre. Reproduced from drawing by Michael Balz with permission from Michael Balz . . Transverse and long sections of the Heliopolis University, Shell of Peace. The lower, long section suggests how the variable curvature of the shell surface will distribute sound more evenly. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . .

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xxvi

Fig. 6.27

Fig. 6.28

Fig. 6.29

Fig. 6.30 Fig. 6.31 Fig. 6.32

Fig. 6.33

Fig. 7.1

Fig. 7.2

Fig. 7.3

Fig. 7.4

Fig. 7.5

Fig. 7.6

Fig. 7.7

Fig. 7.8 Fig. 7.9

Fig. 7.10

List of Figures

Alternative auditorium arrangements a Sekem Forum (top left), b conference hall (bottom left), c divine service (top right); and d concert hall (bottom right) for the Shell of Peace. Reproduced from drawings by Michael Balz with permission from Michael Balz . . Plan view of concept model by Michel Balz of multi-level shell continuous surfaces for the skateboarding club. Photograph John Chilton with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . An oblique view of concept model reveals the sinuous, threedimensional multi-level continuous shell surface proposed for the skateboarding club. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plan of the skateboarding club. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . Sections of the skateboarding club. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Plan and elevations of a proposal for a street bar in Stuttgart. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alternative plan and sections of a proposal for a street bar in Stuttgart. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Proposal for ‘Stuttgart 2000’ city centre lake and housing in the air. Reproduced from image by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross-section of proposed high-rise tree structure for ‘Stuttgart 2000’. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a Conventional high-rise towers on multiple plots with connection only at street level with little or no open space or greenery; b linked towers on more dispersed bases, connected at high level, permit greening of the urban landscape. Reproduced from drawings by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modular residential modules supported above ground on metal structures. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Model of organic-form lightweight modular residential modules. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pylon and cable support system for modular residential units with connected decks forming a deep beam linking the towers. Reproduced from drawing by Michael Balz with permission from Michael Balz . . Plan showing extendable hexagonal layout of the pylon and habitable bridge deck system. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modular room cells on suspended decks. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . Plan of deck with alternative layouts of the modular room cells. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section through the modular room cells. Reproduced from drawing by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . .

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Fig. 7.11 Fig. 7.12

Fig. 7.13

Fig. 7.14

Fig. 7.15

Fig. 8.1

Fig. 8.2

Fig. 8.3

Concept physical model. Reproduced from photograph by Michael Balz with permission from Michael Balz . . . . . . . . . . . . . . . . . . . . . . . Vehicular (blue) and pedestrian (red and orange) circulation routes for extended tower system (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alternative structural solutions investigated by Theresa Nettekoven with: a central pylon trussed cantilever decks; b radial concrete wall planes; and c dispersed steel lattice ribs. Reproduced from drawings by Theresa Nettekoven with permission from Theresa Nettekoven . . . . . . Pylon supporting structure seen from ground level (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr) . . . . . . . . . . . . Photomontage of spatial city introduced into marginal land in an existing landscape (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1965 to 1979 (Image credits and permissions (from top) are as noted in captions for Figs. 2.4, 5.7, 2.5, 2.11, 1.6, 2.15, 2.13, 3.5, 3.20, 3.23 and 6.1) . . . . . . . . . . . . . . . . . . . Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1980 to 1996 (Image credits and permissions (from top) are as noted in captions for Figs. 4.24, 5.15, 5.8, 6.4, 3.36, 3.42, 3.45, 6.13, 6.15, 6.19 and 3.43) . . . . . . . . . . . . . . . . . Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1997 to date (Image credits and permissions (from top) are as noted in captions for Figs. 5.25, 5.19, 7.12, 7.15, 7.13, 6.29 and 6.33) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1

Introduction: Biographical Sketch

Abstract

The chapter introduces Michael Balz’s early years and career development, his first explorations with pneumatic structures, freelance collaborations, initial contact with Frei Otto and Heinz Isler and his long-standing relationship with the International Association for Shell and Spatial Structures.

1.1

Early Years

Michael Valentin Balz, Fig. 1.1, was born in Berlin on the 18 May 1935, to artist Ernst Balz—whose sculpture of the infant Michael is portrayed in Fig. 1.2—the son of a pastor from southern Germany, and sculptor Doris Balz. Doris, who had studied biology and botany as well as fine arts, was the daughter of sculptor, Professor Wilhelm Gerstel, who taught at the Academy in Berlin. She had met Ernst while studying with Professor Gerstel, who was known for his classical representational sculpture. After they married, in 1934, they set up their family home in Berlin-Zehlendorf. From the beginning of the World War II, in 1939, Ernst Balz was a pioneer in the German military. However, in 1944 he was reported as missing in Romania, and, sadly, never returned from the war. Hence, from 1939 onwards, Doris Balz was left to raise the family, Michael and his three siblings, effectively as a single mother. In 1943, because of the anticipated Allied air raids on Berlin, families with children were evacuated to less densely populated areas of Germany. The Balz family went to their parents-in-law in southern Germany, and resettled in Gellmersbach near the Weinsberg district of Heilbronn. Thus, from around the age of eight,

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_1

Michael Balz’s childhood was spent, largely in a simple village environment in rural idyll remote from urban culture. He attended primary school, initially in BerlinZehlendorf, from 1941 to 1943, and then in Gellmersbach, from 1943 to 1945. After six years of secondary school in the Weinsberg district of Heilbronn, he graduated “Mittlere Reife” in the summer of 1951. This was a period that included the highly disruptive years of World War II and the early years of reconstruction of Germany immediately following the war. Southern Germany, especially the city of Heilbronn, had been subject to intense aerial bombing which resulted in widespread destruction. For Michael, it was a matter of solidarity to actively help in the reconstruction, and it seemed to him that to acquire a practical construction skill would be more important in the circumstances, rather than pursuing humanistic or artistic studies like his parents had done. With that objective, on leaving school Michael began working for the established building company Koch und Mayer. He took up an apprenticeship in Heilbronn, where he acquired skills as carpenter and in practical building work—passing the carpenter-journeyman’s examination, in 1953, and then working as a trainee bricklayer with the same company in 1954. These are proficiencies that would be invaluable to him in his later career as an architect. Michael Balz found that being creative using his own practical skills and craftsmanship, as a co-worker with humble colleagues in a supportive environment, was an important life experience. He believes that such experience should be part of the world view of every practically creative person. When in professional practice, new developments can thus be explained, reviewed and implemented. In this way, the success of the realization of one’s visions can be experienced.

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Introduction: Biographical Sketch

Fig. 1.1 Michael Balz and his wife Eva who he met when she was visiting his mother’s studio for a pottery class. Reproduced from photograph by Michael Balz with permission from Michael and Eva Balz

1.1 Early Years

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Fig. 1.2 Sculpture of the infant Michael by his father sculptor Ernst Balz. Reproduced from photograph by Michael Balz with permission from Michael Balz

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In the course of his apprentice and training, it became clear to Michael that all the essential creative prerequisites and decisions affecting the crafts and construction vocations in the planning of projects and objects are devised and created by engineers and architects. For this reason, he took the decision to study civil engineering at the Staatsbauschule [State Construction School] in Stuttgart. In preparation for his planned civil engineering studies, he undertook work experience as an intern in the office of BDA Government Architect, principal, Dr.-Ing. Rudolf Gabel, Heilbronn, gaining experience of works and detail planning, drawing practice, model making, construction management and billing. From October 1955 to February 1957, he completed Semesters 1–3 at the Staatsbauschule, now the Hochschule für Technik [University of Technology] in Stuttgart. This was followed by two periods of practical training. The first, from March 1957 to April 1958, was with Architects BDA Dipl.-Ing. Max Meid and Helmut Romeik, in Frankfurt-amMain, where he was responsible for work planning and detailed planning for a cinema, also for administration buildings and car parks for Allgemeine Orts Krankenkasse (AOK) the German health service. The second, from May 1958 to February 1959, was with architect BDA Dipl.-Ing. Hans Busso von Busse, in Munich, where he was responsible for work planning and detailed planning, building application plans for residential and commercial buildings and an Evangelical Church in Schaftlach/Obb. Returning to his studies in Stuttgart in March 1959, he completed the 4th–6th semesters in the Department of Architecture, becoming qualified as a State-Certified Civil Engineer (today this would be Dipl.-Ing., FH) in November 1960. He started practice as an independent architect in December 1961.

1.2

Entering Practice

Michael Balz estimates that about 30–40% of his professional career to date has been spent with developments of organic architecture while approximately 60% relates to the design of more conventional buildings in southern Germany. Initially, following completion of his studies, Michael carried out freelance work with architect Professor Paul Stohrer, FHT Stuttgart, including detailed planning for offices, and Villa Bitter, Bielefeld, a residential hillside housing complex, also working with Bauer + Strässle, in Stuttgart, on the construction management of housing developments. With this varied experience under his belt and now accepted as a ‘freelance architect’ Member of the BadenWürttemberg Chamber of Architects (Member, No. 3149), in 1963 Michael started to practise as an independent architect. Like many young architects, he participated in architectural competitions to gain exposure for his practice, with proposals

Introduction: Biographical Sketch

for church centres and schools, this motivating design work being supported by more routine commissions producing planning and detailed construction drawings for housing programmes, small settlements and a shopping centre in Lörrach, with larger commercial architectural practices, for instance, in partnership with architects Ernst and Helmut Schaal, Architektur Büro Schaal, in Heilbronn.

1.3

First Shell Explorations

Prompted by his mother asking him why it was not possible for architects to inflate houses, his first models and experiments with pneumatic forming of shells began in 1965 in his mother’s sculpture workshop. His basic research, on organic forms in nature and experiments using gypsum plaster cast over inflated balloons, supported the design development of dwelling shells, which will be discussed in more detail in Chap. 2. This time spent in his mother’s studio also influenced his future in other ways. There, Michael first met his future wife Eva, who was visiting for a pottery class. Initially, the exploration of pneumatic forms led him to consult the eminent Stuttgart architect Rolf Gutbrod (1910– 1999). Gutbrod directed him to his colleague Professor Frei Otto (1925–2015), at the Institut für Leichte Flächentragwerke (Institute for Lightweight Structures, IL), in the then Technische Hochschule Stuttgart (Technical High School Stuttgart) (Balz 2018). There, in 1966, Michael carried out research into the principles of pneumatic and cable net construction ‘Seilnetzkonstruktionen’ under Frei Otto’s direction. At that time Frei Otto and Rolf Gutbrod were collaborating in the design of the innovative cable net and tensile membrane roof for the German Pavilion at Expo’67, in Montreal (Nerdinger 2005), a project that also included a timber gridshell, as roof of a small auditorium (Chilton and Tang 2016). To prove the principle, a prototype cable net, with a single mast 17 m high and 420 mm diameter, supporting a net of 12-mm-diameter steel cables forming a 500 mm  500 mm mesh, and covering approximately 460 m2, was constructed in February 1966 in Vaihingen. After testing the roof, it was proposed to use the prototype structure as the roof for a new building to accommodate the Institute for Lightweight Structures, but at a different site. Before this could happen, a feasibility report and cost estimate were required in order to apply for funding to realize the proposal. As a member of the report team that included Berthold Burchardt, Larry Medlin, Gernot Minke and Frei Otto, Michael Balz contributed to planning of the interior design and detailed fitting out of the cable net structure as a sealed building enclosure at its new location, which is now the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart (Balz et al. 1966; Balz 2018).

1.3 First Shell Explorations

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By coincidence, around forty years later, in 2007–2008, he was associated once again with this building, as architect for the replacement of the original scale-like, acrylic cladding panels of the distinctive tear-drop-shaped skylight of the roof with a new system of mineral composite glass panels, Fig. 1.3. The flat glazing panels needed to be bent in-situ to the curved form of the skylight and the fixings had to accommodate the flexing of the cable net as well as normal thermal and environmental loads and remain fully watertight. Discussions during this refurbishment were the last conversations Michael Balz had with Frei Otto. As one would expect, given Michael Balz’s interest in the use of pneumatic forms in architecture, he attended the 1st International Colloquium on Pneumatic Structures, which was organized by Frei Otto on behalf of the International

Association for Shell and Spatial Structures (IASS), in Stuttgart, in May 1967. Here he was introduced to Professor Dr. Heinz Isler (1926–2009), who was presenting a paper “Pneumatic Shape for Concrete Shells” (Isler 1967) at the colloquium. Isler was fascinated by Michael Balz’s pneumatically formed small residential shell models. Coincidentally, Michael Balz was looking for a structural engineer to assist in the further development and verification of his shells. Thus began their mutually beneficial collaboration in the design and building of reinforced concrete shells that continued until Heinz Isler’s death in 2009. The products of their long-term professional relationship—built shells, competition entries and unrealized projects based on pneumatic and catenary hanging membrane form-finding techniques—will be revealed in later chapters.

Fig. 1.3 External and internal views of the refurbished glazing of the tear-drop-shaped skylight, Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart. Photograph

(left) John Chilton; (right) reproduced from photograph by Michael Balz with permission from Michael Balz

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1.4

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Freelance Collaborations

In 1968, Michael Balz established a freelance collaboration to produce plans and supervise projects with architect Wilfried Beck-Erlang, from Stuttgart, an association which was ongoing until 1975. Their competition entry design for a retirement home village in Wangen/Allgäu, Fig. 1.4, won against strong competition. Subsequently, the partially realized project was awarded a Prix International d’Architecture, in Brussels, in 1971. Realization of this project, including extensions, was complicated, and Michael remained in charge of it until 1975. A community school in Stuttgart-Freiberg (1974) included classrooms of slightly organic shape. For the Planetarium Stuttgart (1974), Fig. 1.5, an external supporting trussed-grid frame of

Introduction: Biographical Sketch

stainless steel tubes was developed, from which the projection dome for the image of the stars was suspended. Other projects included the associated railway station Planetarium and a sports centre in Stuttgart Degerloch. A highlight of this association occurred in 1970, when a team comprising Wilfried Beck-Erlang, Hans Lünz and Michael Balz submitted an entry for an architectural competition “Stuttgart 2000” (Beck-Erlang 1994). Their design included high-density urban residences in “dwelling trees”, based on bridge building principles, Fig. 1.6, and was awarded Grand Prix d’Architecture et Urbanisme, in Cannes, in 1970. Since 1976, Michael Balz has had a similar freelance relationship with the architects’ office of Reiner Graf, Stuttgart with responsibility for design and supervision of

Fig. 1.4 Competition winning design for a retirement home village in Wangen/Allgäu. Reproduced from photograph by Michael Balz with permission from Michael Balz

1.4 Freelance Collaborations

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Fig. 1.5 Planetarium Stuttgart (1974) with supporting external trussed-grid frame of stainless steel tubes. Reproduced from photograph by Michael Balz with permission from Michael Balz

diverse projects. These have included: balconied residential units, Terassenhäuser [stepped terraced housing] designed to high ‘state-of-art’ architectural standards and constructed in accordance with the stringent requirements for house building in southern Germany; a school for children with special educational needs, in Schwabstrasse, Stuttgart; and planning and realization of historic detailed natural stone cladding for the Administration Building of the Stuttgart Postal Directorate in Lautenschlagerstrasse, Stuttgart. In 1994, also in association with Reiner Graf, an experimental double-glazed greenhouse was designed and

built for Professor K. W. Mundry. Located on the roof of the 10th floor of the NWZ II Building, Natural Science Centre of the University of Stuttgart, Pfaffenwaldring 57, the greenhouse was to facilitate research into the tobacco mosaic virus. For the University Construction Office, Stuttgart and Hohenheim, Michael Balz has also worked on the installation of Institutes for Biology in the physics tower block, a botanical experimental facility incorporating a greenhouse and laboratories. While working the project for the Biological Institute of the University of Stuttgart, in 2000,

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Introduction: Biographical Sketch

Fig. 1.6 Entry for an architectural competition “Stuttgart 2000” high-density urban residences in “dwelling trees”, based on bridge building principles. Reproduced from photograph by Michael Balz with permission from Michael Balz

Michael became aware of botanical shell formation in the flowers of orchids. Working in collaboration with Dipl.-Ing. Jens Gühring, from the Institute for Photogrammetry and with the Institute for Lightweight Structures at the University of Stuttgart, the three-dimensional shape of petals was measured accurately. The geometry was then converted into triangular meshes to enable the investigation of their structural properties through computer finite element analysis, to better understand the physical structure of the petals and how they are optimized (Balz and Gühring 2001).

1.5

Individual Projects

Since 1976, Michael Balz has also worked as an independent architect. He has designed houses for single and multiple family units in Zell am Neckar, Fig. 1.7, and in Sielmingen, Leinfelden-Echterdingen and Birkenfeld, Fig. 1.8. These were designed and realized to the client’s brief and requirements and built according to the relevant building regulations in Baden Württemberg. They are functional dwellings of exemplary standard where the design style

1.5 Individual Projects

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Fig. 1.7 Single and multiple family units in Zell am Neckar. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 1.8 Section (top) and elevation (bottom) of design for villa in Birkenfeld. Reproduced from drawings by Michael Balz with permission from Michael Balz

10 Introduction: Biographical Sketch

1.7 Relationship with the International Association for Shell …

relates to the site context and environment without significant conspicuous architectural expression.

1.6

Shells and Visions

However, Michael Balz is best known for his internationally recognized projects: Zuschauer halle (Auditorium), Theater unter den Kuppeln, Stetten, Leinfelden-Echterdingen (1976), Naturtheater, Grötzingen, Aichtal (1977), Ballettsaal (Ballet Salon), Stetten (1979), his own family’s house, as a demonstration dwelling for organic/sustainable living (1980– 81), Musical-Saal (Music Salon), Stetten (1988–89) and canopies at Europa-Park, in Rust (1992), which mainly feature free-form thin reinforced concrete shell roofs, all realized in collaboration with Heinz Isler as structural engineer. These shells are described in detail in Chaps. 3 and 4. Yet, this list of completed shells is not the whole story. Over the years there have been a number of exciting competition entries, starting with a design for an Evangelical Lutheran church in Heilbronn, in 1967. These are presented in Chap. 5. Additionally, there are many unbuilt projects, including the most recent for a Heliopolis Shell of Peace, Sekem, Cairo proposed in 2016–2017. A selection of unbuilt projects is revealed in Chap. 6. Since the 1970s when he participated in the design team for the “Stuttgart 2000” competition, Michael Balz has continued to develop his vision for modern urban living. With dwelling units on sky bridges suspended high above street level between pylon structures used for access, this architecture is far removed from the very-grounded shells. His philosophy of urban living in the twenty-first century, where the world population is increasing at a rate of over 200,000 per day (Worldometer 2020), is portrayed in Chap. 7.

1.7

Relationship with the International Association for Shell and Spatial Structures (IASS)

Over the latter years of his career, Michael Balz has had a close affiliation with the International Association for Shell and Spatial Structures (IASS), based in Madrid. Formerly, the International Association for Shell Structures, the IASS, was founded in 1959 by the eminent Spanish engineer Eduardo Torroja (1899–1961) as a forum for architects and engineers interested in the development of reinforced concrete shell structures. Although Michael had attended his first IASS sponsored event in 1967, it was not until 1985 that he became a member. However, since then he has been very active in the association.

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1.7.1 Tsuboi Award In 1990, Japanese structural and architectural designer Professor Yoshikatsu Tsuboi (1907–1990) sadly died during his second term as the IASS President. In his memory, his wife, the late Kazuko Tsuboi, established the IASS Tsuboi Award. Two prizes are given annually, one “… for the most meritorious paper published in the Journal of the IASS in the preceding calendar year” and the other “… for the most outstanding paper presented and published in the Proceedings of the previous year’s annual IASS Symposium” (IASS 2019). The very first award of this prestigious honour for the most commendable paper published in the Journal of the IASS was presented to Michael Balz, in 1991, for the publication of “Architectural aspects of organic forms and design of concrete shells” (Balz 1991). The prize, a Japanese lacquered thin shell sculpture, of about 330 mm in diameter, shown in Fig. 1.9, was designed by Hiroko Hatekenaka and Ryohei Miyata, beautifully handcrafted by Takuji Ogimura, with the process overseen by Professor Tsuboi’s son Yoshiaki Tsuboi (IASS 2019).

1.7.2 IASS Structural Morphology Group In 1991, during their Annual Symposium, held in Copenhagen, the IASS established Working Group 15 (WG15) devoted to the study of Structural Morphology—better known as the Structural Morphology Group or (SMG). An initial meeting of 16 enthusiastic conference attendees was held on 5 September 1991, at the ‘Færge Cafeen’ bar in Copenhagen. Michael Balz was one of those who found their way from the main symposium venue together with Heinz and Maria Isler, Shikiko Saitoh, Pieter Huybers, René Motro, Tony Robbin, Koji Miyazaki, Philippe Samyn, N. K. Srivastava, A. H. Noble, Wolf Pearlman, François Gabriel, Ture Wester and myself (Wester 2009; Chilton et al. 2018). Here René Motro agreed to hold a first seminar in Montpellier in 1992. The second seminar, “Application of Structural Morphology to Architecture” was held in Stuttgart, in 1994. Reflecting his passion for the promotion of non-conventional structural forms, the first day of the seminar was hosted by Michael Balz, in Stetten, under the thin reinforced concrete shells he had developed with Heinz Isler for the “Theater unter den Kuppeln”. During the seminar, participants were treated to Michael’s explanation and presentation of scale models related to his paper in the proceedings, entitled “Modular Structures in Organic Design” (Balz 1994) as well as a dramatic practical demonstration of shell form-finding by Heinz Isler (Isler 1994; Chilton et al. 2018).

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Introduction: Biographical Sketch

Fig. 1.9 IASS Tsuboi Award received by Michael Balz in 1991. Reproduced from photograph by Michael Balz with permission from Michael Balz

1.7.3 Executive Council and Advisory Board Later that year, in recognition of his work with shell structures, perhaps boosted by the success of that day of the seminar and the support of the large SMG membership, Michael was elected to the Executive Council of IASS. In 2010, he became a member of the IASS Advisory Board, which is composed of former Executive Council members. He continues to support the running of the organization in a consultative capacity and will be granted Honorary Membership at the Symposium in 2023.

References Balz M (1991) Architectural aspects of organic forms and design of concrete shells. Bull Int Assoc Shell Spat Struct 32, 2(106):79–86 Balz M (1994) Modular structures in organic design. In: Höller R, Hennicke J, Klenk F (eds) Application of structural morphology to architecture. Proceedings of 2nd international seminar on structural morphology. Institut für Leichte Flächentragwerke [Institute for Lightweight Structures], University of Stuttgart, Germany, pp 1–10 Balz M (2018) Recorded conversation with John Chilton at the Balz House, Stetten auf den Fildern, 5 June 2018 Balz M, Gühring J (2001) Botanic shell structures. In: Kunieda H (ed) Theory, design and realization of shell and spatial structures. Proceedings of the IASS symposium, Nagoya, Japan. International Association for Shell and Spatial Structures, Madrid, p 7. Extended abstract 288–289, Paper TP128. Available https://citeseerx.ist.psu. edu/viewdoc/download?doi=10.1.1.17.3531&rep=rep1&type=pdf. Accessed 25 June 2021

Balz M, Burckhardt B, Medlin L, Minke G, Otto F (1966) Studie zum Ausbau des Versuchsbaus Stuttgart-Vaihingen [Study for the expansion of the test building Stuttgart-Vaihingen]. Unpublished document (217-0180, gta Archives, ETH Zürich) Beck-Erlang W (1994) Project Stuttgart 2000. In: Höller R, Hennicke J, Klenk F (eds) Application of structural morphology to architecture. Proceedings of 2nd international seminar on structural morphology. Institut für Leichte Flächentragwerke [Institute for Lightweight Structures], University of Stuttgart, Germany, pp 11–20 Chilton J, Tang G (2016) Timber gridshells: architecture, structure & craft. Routledge, London Chilton J, Huybers P, Hennicke J (2018) Structural morphology group —the first 10 years. In: Mueller C, Adriaenssens S (eds) Creativity in structural design. Proceedings of the IASS symposium 2018. MIT, Boston, p 8 International Association for Shell and Spatial Structures (IASS) (2019) Tsuboi awards recipients. Available https://iass-structures.org/ Tsuboi-Award-Recipients. Accessed 5 Nov 2019 Isler H (1967) Pneumatic shape for concrete shells. In: Proceedings of the 1st international colloquium on pneumatic structures. University of Stuttgart, Stuttgart, pp 50–51 Isler H (1994) Creating models. In: Höller R, Hennicke J, Klenk F (eds) Application of structural morphology to architecture. Proceedings of 2nd international seminar on structural morphology. Institut für Leichte Flächentragwerke [Institute for Lightweight Structures], University of Stuttgart, Germany, pp 221–230 Nerdinger W (ed) (2005) Frei Otto complete works: lightweight construction natural design. Birkhäuser, Basel Wester T (2009) The first 13 years of structural morphology group—a personal view. In: Motro R (ed) An anthology of structural morphology. World Scientific Publishing, pp 1–14 Worldometer (2020) World population, net population growth today. Available https://www.worldometers.info/world-population/. Accessed 17 Feb 2020

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Evolution/Organic Architecture

Abstract

This chapter introduces Michael Balz’s initial exploration of Urschalen, prototype organically formed shells for dwellings, which he carried out in his mother’s sculpture atelier and the first steps in his long-standing professional collaboration with Swiss engineer, Heinz Isler. It illuminates his vision to find a form of living environment that accommodates organically to the needs of life, while taking advantage of the latest shell construction methods of the time—the late 1960s. It concludes with individual designs for in-situ concrete shell dwellings, including a proposal for a house for Heinz Isler, and proposals for ‘bio-segment’ modular prefabricated shells, intended for mass production.

2.1

Introduction: Organic Architecture

The term organic architecture is generally credited to Frank Lloyd Wright (1867–1959). Today his philosophy of fully integrating all aspects of the design of a building while relating this to the surrounding natural environment—a synchronicity between architecture and nature—might be interpreted as what is now referred to as sustainable architectural design. The term organic architecture is also associated with the buildings designed by the Austrian philosopher Rudolf Steiner (1861–1925), such as the 1st and 2nd Goetheanum and the work of Bruce Goff (1904–1982). Steiner, founder of the anthroposophy movement, also influenced proponents of organic architecture such as the Hungarian architect Imre Makowitz (1935–2011) (Heathcote 1997) and Hans Scharoun (1893–1972) in Germany. However, for Michael Balz the term organic architecture is better reserved for architectural forms directly inspired by natural objects, such as the double-curved surfaces of sea shells, flower petals and nutshells, Fig. 2.1a–c. © Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_2

2.2

Urschalen (Primitive or Proto-Shells)

There are no straight lines or sharp corners in nature. Therefore, buildings must have no straight lines or sharp corners. Antoni Gaudí

In the late 1960s and early 1970s following the turmoil of World War II and the gradual economic and social recovery of the 1950s, many in society were beginning to explore alternative lifestyles and look for novel architectural solutions to reflect their exciting new visions for the future. Having first become interested in pneumatic forming of shells in 1965, Michael Balz began to experiment with architectural pneumatic free-forms in his mother Doris Balz’s sculpture atelier after his mother had asked him why it was not possible to make ‘blow-up’ houses. Using gypsum plaster to form model shells on inflated balloons, he was able to create small-scale domed forms with a view to scaling them up to create habitable dwellings of innovative form (Balz 2011). The Urschalen prototype shells for living were developed at a scale of 1:50 and 1:20, by casting gypsum plaster over elastic membranes (balloons) inflated within a variety of curvilinear plan templates. Two alternative shell forms and possible living configurations are shown in Fig. 2.2. From left to right, these show: the initial cast of the inflated form; proposed window and door openings marked on the shell; shell with cut-out openings; proposed internal planning under the shell. Michael Balz realized that the pneumatic formation process can generate the same shapes at any scale. However, at the large scale, the ‘balloons’ must be assembled from individual flat strips and, in order to develop the best way of cutting them, he realized that the seams can be drawn and measured on the physical model. When scaled-up appropriately, these measurements would serve as a “cutting pattern”. For the full-scale balloon envelope, he selected a special-purpose rubber membrane,

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Fig. 2.1 Natural forms used by Michael Balz to inform his design of free-form shells: a precious wentletrap, Epitonium scalare. Photograph John Chilton. b Exterior and interior structure of chambered nautilus,

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Evolution/Organic Architecture

Nautilus pompilius. Photograph John Chilton. c Lady’s-slipper orchid, Cypripedium calceolus. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 2.2 Urschalen: development of two alternative prototype shells for living showing—from left to right: the initial cast form; proposed widow and door openings; shell with cut-outs; proposed internal planning. Reproduced from photographs by Michael Balz with permission from Michael Balz

2.2 Urschalen (Primitive or Proto-Shells) 15

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BAYPREN®1 (Baypren® 2020) to ensure that under pressure the desired shape is created, as determined by the cutting pattern. He also noted that this material has a high wear resistance, so that the balloons, once produced, could be used many times to achieve high construction efficiency and improved profitability. The prefabricated balloon formwork could easily be transported to the construction site where it could then be simply anchored to the foundation and inflated. He proposed three different anchoring systems. For the first, Fig. 2.3 (left), which he suggested would be particularly suitable for temporary plastic shells where no concrete foundation is required, the balloon envelope includes a tube around the perimeter. Once the balloon is spread out on the ground, the perimeter serves as a template for the shape of the shell and the foundation trench can be excavated. Once the trench has been dug, the perimeter tube is filled with water and this holds the balloon evenly onto the ground at the edges, accommodating to irregularities in the foundation trench. To ensure that the tube does not twist when the balloon is inflated and that it applies a vertical force, a second small membrane sheet is applied on the inside to connect the inner part of the tube with the main membrane. This inner sheet is perforated so that on inflation the internal pressure also acts on the outer skin in the lower part of the balloon, Fig. 2.3 (left, centre row). If the ground is soft and damp, the floor membrane can potentially be omitted as the tube will self-seal against the soil. For lightweight foam shells, produced with this foundation method, once the polyurethane has set, the water is drained from the base tube and the balloon can be removed. The foundation trench is then filled in, inside and outside, and rammed to protect the light base and prevent twisting. Weather protection can be provided with an external waterproof membrane or GRP coating. For the second, Fig. 2.3 (centre), a rigid concrete foundation is constructed with metal hooks cast in every 20 cm to attach to loops on the balloon—an anchoring method that had already been successfully applied with inflated formwork for around 30 years, for example in Wallace Neff’s ‘Airform’ houses (Anon 2020). Once the membrane balloon is installed, it is then inflated to the required internal pressure, which depends on the weight of the construction layer (or layers) to be applied. If thermal insulation is required, polyurethane foam can first be sprayed onto the external surface of the inflated form followed by concrete applied using the Torkret (or gunite) method. Any surface unevenness can be smoothed manually while the concrete is still workable or later with grinding

equipment. On removal of the balloon formwork, an internal coating of concrete or plaster can be applied. For the third, a compressed air hose or similar is cast into the concrete foundation with a wedge-shaped channel over this (formed by a board curved according to the plan shape of the shell), Fig. 2.3 (top right). After the air hose and the conical board have been removed, the lower edge of the “BAYPREN” balloon is introduced into the slot and a “BAYPREN” tube is inserted loosely. When this tube is inflated, a hermetic seal is formed at the base of the balloon, Fig. 2.3 (centre right). This method has the advantage that, rather than the normal external coating, the balloon can be coated from the inside. The areas of the shell that are hatched in Fig. 2.2 (second left) are not coated: here rooflight domes or vertical glass walls will be introduced later. If an airlock is installed in one of the hatched areas, it allows the balloon to be entered without loss of air pressure, and it is possible to spray the base layer from the inside. In that case, construction can be independent of the weather. The channel left after removing the perimeter tube, and membrane can also be used to supply air for a heating or air conditioning system. The twin-shell construction with thermal insulation on the inside and concrete shell on the outside, Fig. 2.3 (bottom right), had already been tested in industrial construction. In this case, the outer skin needs to be vapour permeable. If the concrete shell form is modelled on a pressure surface, the formation of hairline cracks in the concrete is limited. Hence, if a suitable waterproofing admixture is used in the concrete, an impermeable outer skin is not required. After the sprayed materials have hardened, the air pressure can be released and the balloon can be removed—a thin load-bearing shell construction has been created.

1 Baypren® is a Registered Trademark of ARLANXEO Deutschland GmbH.

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2.3

Collaboration with Heinz Isler

As confirmed by his wife Eva,2 who recalled that she was pregnant with their eldest son, Johannes, at the time, Michael Balz’s interest in thin reinforced concrete shells was bolstered by his meeting Swiss engineer Heinz Isler at the 1st International Colloquium on Pneumatic Structures held in Stuttgart, in May 1967. Heinz Isler appreciated Michael Balz’s understanding of the modelling methods used to create his Urschalen, a method similar to that employed by Isler to form-find his industrial ‘bubble’ shells. United by their common interest in pneumatic form-finding, their meeting in Stuttgart was followed by the Balz family visiting the Isler’s in Burgdorf, Switzerland, that summer. From then

In conversation with John Chilton at the IASS Symposium Dinner, Barcelona, 10th October 2019.

2.3 Collaboration with Heinz Isler

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Fig. 2.3 Alternative proposals for foundation systems for the pneumatic-formed shells. Reproduced from drawings by Michael Balz with permission from Michael Balz

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Fig. 2.4 Examples of model Urschalen pneumatically formed shell houses photographed by Michael Balz while visiting Heinz Isler in summer 1967 on the bank of the River Emme, close to Isler’s office. Reproduced from photographs by Michael Balz with permission from Michael Balz

on, they visited most years and Heinz Isler became almost like an uncle to their children, entertaining them with his model trains that looped around the grounds of the Isler office at Lyssachschachen. His initial experience of this form-finding technique having been reinforced in the studio of Frei Otto, in 1966, Michael Balz had taken some of his Urschalen with him when visiting Heinz Isler in the summer of 1967 and photographed them at the bank of the River Emme, which runs just a few metres away from the Isler office, Fig. 2.4. At this time, Heinz Isler’s pneumatic method of formfinding for industrial shell roofs (Isler 1961) was wellestablished, and he had already built many of his standard square or rectangular ‘bubble’ shells with spans up to a maximum of 54.6  58.8 m (Chilton 2000; Ramm and Schunk 2002). Sharing Michael Balz’s fascination with natural forms, when shown his prototype shells, the engineer recognized their latent potential for use as small-scale residential units and urged Michael Balz to persist in his research. This mutual interest formed the basis for a long-standing very productive professional relationship and personal friendship that was sustained until Heinz Isler’s death in 2009.

The two approaches, that of the architect supported by that of the engineer for structural verification and rational execution, came together to inspire Michael Balz to propose new organic shapes for housing based on innovative construction methods. These were published in a pamphlet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing—New Construction Methods) (Balz and Isler 1968). Although published under joint authorship, the ideas and vision described therein were primarily those of Michael Balz, which, as he says, Isler “followed”. This pamphlet was profusely illustrated with black and white photomontages of small gypsum models cast on pneumatically formed membranes and floor plans of houses intended to accommodate households of various sizes up to 5 or 6 people. In many ways the leaflet is a valuable historical and sociological record, as it encapsulates an optimistic image of a future made more comfortable by the exploitation of developing technologies, which was prevalent at the time. Yet it also shows evidence of the nascent recognition that human society needs to consider and limit its impact on the natural environment. For that reason, its proposals are shared and re-evaluated in the following sections.

2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen …

2.4

Geborgenes Wohnen heute und morgen: neue Wohnformen: neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing: New Construction Methods)

On the cover of the leaflet, shown in Fig. 2.5, there is a photomontage showing a futuristic, organically shaped house displayed in a rural setting and fashioned to blend into the landscape. Within the leaflet—which might be considered to be more like a condensed manifesto for a distinctive vision of modern living in the 1970s—attention is drawn to twelve aspects of the design, and these are each elucidated here.

Fig. 2.5 Front cover of the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing—New Construction Methods).

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2.4.1 Was sind menschliche Wohnformen? (How Would One Define Human Habitation?) To begin, Michael Balz, with the endorsement of Heinz Isler, defines the brief that the design proposals are intended to satisfy: to attempt to find a form of living environment that accommodates organically to the needs of life, while taking advantage of the latest construction methods. Here it is described how, if one looks at the way individuals move, one can see that they walk then linger, move then rest. As a result, it is clear that people need space to move, paths to follow and inviting, safe places to pause and rest. It is observed that people rarely change direction at

Photograph John Chilton with permission from Michael Balz and the Isler family

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right angles while walking—they cut corners; that no movement of human limbs is inherently linear; and that the human anatomy favours movement along curves in either two or three dimensions, Fig. 2.6. Also, attention is drawn to the observation that, in the social environment, equanimous conversations occur at round tables, we have circles of friends and, due to the optics of the human eye, we see others in a circular view. The conclusion was that only built envelopes of rounded and curved form can genuinely meet these primal needs.

2.4.2 Was ist Geborgenheit? (What Is Security?) The second section of the leaflet introduces the human need for security, a safe environment in which to live, a need that Michael Balz believes every home should meet. In fact, the German word “Geborgen” or “Geborgenheit” can be used to express feelings of cosiness as well as being protected from danger. He intimates that from the psychological point of view, it has been demonstrated that enveloping, protective, womb-like forms best fulfil this need, Fig. 2.7. This argument adds support to the proposal to enclose living areas with double-curved shells, in which the walls and ceiling blend effortlessly into one seamless embracing form. It is proposed that each significant part of the home should have its own shell but, so that the whole is seen as a unit, the individual domed spaces should be melded together into an all-encompassing surface. Nevertheless, it is stressed that the home should not be unnecessarily large and should have human proportions. This recommendation to limit the size reflects the emerging environmental concerns of the time that are equally, if not even more, relevant in the early twenty-first century, over fifty years later.

2.4.3 Die Aufgabe (The Task) Endeavouring to define the design task more specifically, it is suggested that the private house, one’s home, is a human being’s most intimate possession. Consequently, no effort should be spared to find out what aspects of its nature best meet and deliver the appropriate framework for the development of a person’s talents. It is up to the individual to explore and understand the important aspects of his or her environment, in order to cope with them well, both spiritually and technically. To this end, one needs one’s home, one’s living space to be a stable base. The home is the second most important protective layer for the human body after clothing. In one’s youth, the home environment directly influences one’s development and shapes one’s future spirit and being. The residence is seen to be a protective shell, which separates the private realm of the individual and their family

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from the infinity of space. It reflects the spirit and personality of its occupants through its shapes and colours. It is noted that throughout history, humankind has applied the latest available knowledge in their buildings: this has been true in respect of technical, hygienic, psychological, and, last but not least, artistic terms. It is suggested that, even today, this is our duty: that we need to make today’s built environment to accommodate the contemporary lifestyle of individuals using the production methods and materials of our time. Today, once again, we might include the need to minimize the environmental impact of the living shells by controlling the embodied energy from the construction and operational energy over the life of the dwelling.

2.4.4 Die Zukunft (The Future) Radically different architecture is envisioned for the future. It is argued that housing design should not be forced to follow any particular aesthetic heritage, or be weighed down by rigid convention and tradition. On the contrary, designers should be able to propose any solution that is as effective as possible in supporting human activities and any special design requirements. It is recognized that, at the time (in the late 1960s), the materials and manufacturing techniques available to architects and engineers are like never before and open up completely new aspects of space planning and home décor: of course, this argument applies equally, if not more so, in the 2020s. This leads to Michael Balz raising an important question: does a sensitive person really feel comfortable in a box-shaped house or apartment, which is filled with box-like furniture, that has an inflexible character, just because it is “ready to go”? Perhaps foreseeing the present emphasis on off-site volumetric production of housing units, it is predicted that the future will be full of instantly usable, fully finished housing units, which will be manufactured as a whole according to the various needs and preferences of their future occupants. It is suggested that the trend is moving away from possessing individual items of furniture that can accompany one through life and be dragged from home to home. However, given the rise of companies such as IKEA in the intervening years, who specialize in selling self-assembly, easily transportable furniture, this prediction was perhaps a little premature. Another aspect where attitudes have changed over the last 50 years is in the attitude to the use of plastics. In this vision of the future, it is expressed that plastics deserve special attention in building: they are plastically deformable, have high tensile and compressive strength, are available in all colours and transparencies ranging from that of clear glass to opaque. Thermal insulation properties can be adapted to

2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen …

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Fig. 2.6 Michael Balz’s sketches showing that the human anatomy favours movement along curves. The layout shown is that of the Balz House described in detail in Chap. 4. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 2.7 Michael Balz’s sketches showing how rounded forms enhance feelings of security and social interaction. Reproduced from drawing by Michael Balz with permission from Michael Balz

2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen …

each need, and the densities are low. Today there is, perhaps, less enthusiasm for such materials unless they can be reused or fully recycled, and architects are trying to avoid materials that are seen to pollute and persist in the environment for hundreds if not thousands of years. It is also asserted that the possibilities of reinforced concrete construction had not been fully explored and that there were exciting possibilities yet to be realized. This is to some extent still true today. A well-designed concrete shell is one of the most appropriate and efficient uses of this infinitely mouldable material, yet few are currently constructed.

2.4.5 Eine Bauweise heute (Construction Today) The curved-form habitable shells illustrated in the leaflet, Fig. 2.8, can be produced with various proven construction techniques of the time. For example, as described for the Urschalen earlier, it is possible to cast them using sprayed or poured concrete, or other materials, on pneumatic formwork, which can be used any number of times. The balloon-like moulds can be “tailor-made” based on the accommodation needs of the intended occupants and allow for an infinite number of variants. In addition to more conventional building materials, foams that are easy to form and process can be used to shape the interior fittings. These can then be covered with upholstery fabrics or hard plastic surfaces according to purpose, using all imaginable colour combinations. Therefore, there are hardly any limits to individual aspirations.

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2.4.6 Die Entwurfsmethode (Design Method) Michael Balz wanted to look at the complex problem of “living” from fundamental principles. Therefore, he started his initial investigation with the most basic, independent single residential housing unit, which can be shaped according to the internal needs of the occupants and with reference to the external environment. He argues that such dwelling units can be manufactured today in new building forms without difficulty, both individually and in clusters. Anticipating his own vision of urban dwelling (described in detail in Chap. 7), and perhaps with the precedent of Moshe Safdie’s Habitat innovative housing for Expo’67 in Montréal, Québec, Canada in mind (Safdie Architects 2020) —but in curvilinear rather than rectilinear form—he suggests that one can visualize the development of similar residential cells that could eventually be stackable, be incorporated into high-density housing, or be suspended in extensive spatial structures. Michael Balz considered that the residential unit needed to be designed as a whole including both the structure and envelope, and the internal fixtures and fittings. Accordingly, almost everything that he anticipates the family will need is modelled from the overall form. The only movable individual items of furniture are chairs, armchairs, cushions and tables. He argues that only with this method can all spatial design possibilities of the dwelling be fully developed: flexibility of the larger furnishings or larger parts of the house is always at the expense of the current use. There are no dead corners: all available space is fully utilized, and each individual room is shaped to its specific purpose.

Fig. 2.8 One of the model, curved-form, habitable shells illustrated in the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen— neue Baumethoden. Reproduced from photograph by Michael Balz with permission from Michael Balz

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2.4.7 Der Übergang zur Natur (Link to the Natural Environment)

2.4.9 Eine kleine Landschaft zum Wohnen! (A Small Landscape for Living!)

As can be seen in the plan of a typical two- to four-person living shell, Fig. 2.9, the modelled form of the shell is designed to create partially sheltered and enclosed spaces around the main entrance and also as an intimate patio/ terrace for relaxation in front of the living areas. A cantilevered section of the shell acts as a sunshade, deflects the rain and protects the patio from wind and from being overlooked by the neighbours. Extensive vertical glass walls in the south elevation of the main living area provide views of the garden or surrounding landscape, introduce abundant low-angle sunlight in winter but are shaded from the high-angle sun by the cantilevering shell in summer. Circular skylights introduce additional light to other areas, as required, and provide continually changing views of the sky with clouds, of stars, or treetops. Some parts of the home are partially sunken into the ground and, with time, unless it is regularly cleaned or painted, the concrete surface of the shell naturally becomes covered with lichens and mosses. If desired, the shell can also be disguised (or almost totally hidden) with ivy or other climbing plants grown over the surface to help it to blend into its surroundings. To the exterior, there is the opportunity to wrap the lower part of the shell with earth banking. This anticipated the development of fully earth-sheltered housing, such as Underhill, the house, built at Holme, West Yorkshire, UK, by architect Arthur Quarmby (1934–2020) as his own residence, which was completed in 1975 and is now listed Grade 2 (Historic England 2017).

To emphasize the feeling of security, the hollow form of the living room was designed to be three steps lower than the entrance level—although, today, with greater awareness of accessibility for those with mobility problems this would probably now be all at the same level or require the introduction of a short ramp. The living room opens to the south and west to benefit from the afternoon and evening sun. Wraparound seating, built-in cupboards and shelving follow the internal curve of the shell. The seating is only partially covered in cushions to allow alternative uses. The curved inner surface of the shell allows lighting at night to be adaptable. With various direct, adjustable lamps and indirect lighting reflected off the internal curved surface, the mood of the living space can be adapted to suit. As noted in the pamphlet, a light source such as an aquarium with fish moving constantly within it will cast strange but interesting constantly changing shadows against the dome.

2.4.8 Der Eingang (The Entrance) Orientation and room layout of the living shells are considered to be very important and are designed to give natural light and views for the main living spaces. The entrance of the two-person shell house, of 95 m2 in plan, Fig. 2.9, is to the north and sheltered by a cantilevering shell. On entering, to the left (the east) are the main living area and kitchen/ diner, with bathroom and bedroom to the right (the west), with cloakroom between. These linked domed spaces all have open views into the garden, to the south, and embrace a sheltered south-west facing terrace. This is designed to catch the afternoon sun, which allows the living space to expand into the garden in good weather. A small internal plant pool by the entrance refreshes the internal environment. The five- to six-person version, Fig. 2.10, has a similar disposition of accommodation but with additional bedrooms for children and guests.

2.4.10 Die geschlossene Ruhezone (The Closed Rest Zone) To catch the morning sun, the bedroom faces south-east. There is space for a large built-in wardrobe against the wall adjacent to the bathroom. Also, storage fittings for linen, shoes, a dressing table and a small writing and reading area adjacent to the window. Located next to the bedroom, the bathroom is modelled and manufactured as one unit, with bath, wash-hand basin and WC and drained floor, to create a wet room that is well sealed and is easy to clean, as all parts are rounded.

2.4.11 Die praktischer Arbeitsraum (The Practical Workspace) The kitchen is simultaneously a practical workspace and storage space. For security, the main house entrance is overlooked by the kitchen window. As is fashionable in kitchens today, there is a central island unit with built-in hot plates, with fume extraction over. The kitchen sink is set in a large worktop under the window and the worktop merges into the breakfast bar, which reaches out into the living room. Spacious storage cabinets with refrigerator, cupboards, oven, barbecue, dishwasher and the washing machine, ironing board and drier are built-in in a semicircle around the central island. It is proposed that all equipment should be easily interchangeable, so that the latest products

Fig. 2.9 Two- to four-person shell house, of 95 m2 in plan from the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden. Reproduced from drawing by Michael Balz with permission from Michael Balz

2.4 Geborgenes Wohnen heute und morgen: neue Wohnformen … 25

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Fig. 2.10 Larger five- or six-person shell house, of 125 m2 in plan from the leaflet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden. Reproduced from drawing by Michael Balz with permission from Michael Balz

26 Evolution/Organic Architecture

2.5 Living Shell Projects

can be used. This view, although almost universal at the time, would almost certainly be challenged today, as being unsustainable—although the substitution of older energyhungry appliances with new energy-efficient devices could be beneficial.

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atmosphere of social change that existed at the time. There were, however, a few projects based on these ideals that remain unbuilt.

2.5.1 Private Client, 1968 2.4.12 Minimaler Materialaufwand (Minimal Material Consumption) This is one of the key benefits of the proposed ‘living’ shells. They are significantly more efficient than the equivalent standard construction methods structurally speaking, since they are largely self-supporting and self-stiffening, because of their double curvature, like egg shells. This means that the concrete shells are only a quarter to one fifth of the thickness of a flat reinforced concrete slab ceiling of equal span. A further saving of material arises from the fact that the surface area of the shell is less than that required for a rectilinear building of similar volume—for example, the surface area of half a cube is 1.24 times that of a hemisphere having the same enclosed volume. The external surface area is smaller, and the shape is also aerodynamically smoother than comparable conventional buildings. Hence, in winter, the loss of heat through the external surface is reduced— with a similar reduction in heat gain in summer—thereby achieving a considerable saving in heating and cooling energy consumption, greenhouse gas emissions, and cost.

2.5

Living Shell Projects

This vision of housing in the mid-twentieth century does not appear to have captured the imagination of the general public, as, apart from the upper floor of Michael Balz’s own house, which is reviewed in detail in Chap. 4, no living shells were built to his designs. As Michael Balz remarks, natural living spaces were a trend. Although he was not aware of them at the time, he now realizes that there were other experimental organic dwellings, for example the sculptural architecture of Jacques Couëlle (1902–1996) built on the Mediterranean Côte d’Azur, in south-east France (Perkin 1970; Anon 1971). Also the Californian architect Wallace Neff (1895–1982) constructed concrete shells on inflated forms from the early 1940s, and lived in one himself. Known as ‘Airform’ bubble houses, they were, however, simple domed forms (Los Angeles Conservancy 2020; Anon 2020) quite unlike the moulded free-form of Michael Balz’s living shells. It could be that Michael Balz’s ideas were just too novel for most people in Germany to accept, despite the

In December 1968, with an (unbuilt) commission for a private client, Michael Balz produced a sketch design for a larger and more complex dwelling based on the principles outlined in Sect. 2.4, see Fig. 2.11. Here living spaces were integrated with a ‘wintergarden’ and an indoor swimming pool. This was a development necessitating more sophisticated planning, which included additional accommodation located in a basement below the more architecturally adventurous shell forms. The forms shown in the sections suggest that they were derived from pneumatic models. Although this project was not built, similar developments were later incorporated in the design for a house for Heinz and Maria Isler.

2.5.2 House for Heinz and Maria Isler (1972–73) Heinz Isler, Michael Balz’s engineer for his proposals for this new form of living, designed and built his own design office in Lyssachschachen, near Burgdorf, in Switzerland, in 1964. Although the office building included the innovative use of prestressed concrete to engineer a flat unprotected but fully waterproof roof, it was still a relatively standard rectilinear two-storey structure on a ‘Y’-shaped plan around a small atrium. Wishing to live close to the office, and to create a full-scale prototype of the shell house, in 1972, Heinz Isler and his wife Maria commissioned Michael Balz to design a house for them, to be located in the extensive grounds of the Isler office. Several alternative schemes were proposed, such as that shown in the site and floor plans, Figs. 2.12 and 2.13. Most of these schemes incorporated one or more domed shells atop an earth-sheltered garage, workshop and living accommodation. Sadly, none of the alternatives was built. Michael Balz says that the main reason for this was not because an acceptable architectural solution could not be found but because of the local trains that pass along the south-west boundary of the site. For safety reasons, the frequently passing trains are required to whistle as a warning to pedestrians and vehicles at two level crossings close to the site. Despite the sound insulation that would have been provided by the shell roof, Maria Isler was concerned that she would not be able to tolerate this persistent loud

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Fig. 2.11 Sketch section through proposed living shell dwelling for a private client, in 1968. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 2.12 Ground floor plan of one of the alternative house proposals for Heinz and Maria Isler at Lyssachschachen, near Burgdorf, Switzerland, 1972. Reproduced from drawing by Michael Balz with permission from Michael Balz and the Isler family

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Fig. 2.13 Upper floor plan of the same house proposal for Heinz and Maria Isler at Lyssachschachen, near Burgdorf, Switzerland, 1972. Reproduced from drawing by Michael Balz with permission from Michael Balz and the Isler family

2.5 Living Shell Projects

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Fig. 2.14 Michael Balz’s model of the preferred scheme for Heinz and Maria Isler’s house at Lyssachschachen, near Burgdorf. Reproduced from photograph by Michael Balz with permission from Michael Balz and the Isler family

intrusion into her home. She was exposed to the sound all day while working in the office so was aware of how intrusive it could be! The architectural model of the preferred scheme is shown in Fig. 2.14. This model was still to be found displayed in the basement of Heinz Isler’s office (albeit in a rather dusty state) at the time of his death in 2009. Nonetheless, the effort invested in these designs was not totally lost. Eight years later, when Michael Balz had the opportunity to build a house for his own family at Stetten, near Stuttgart, he was able to modify the design to suit his own family requirements. This time the domed shell was built, and its detailed construction is described fully in Chap. 4.

2.5.3 Bio-segment Based on biological characteristics of repetitive patterns and natural growth forms, for instance the way seeds are packed in a drying flower head, in January 1971, Michael Balz proposed his ‘bio-segment’ system of dwelling or living cells. This consisted of complete factory-produced prefabricated shell-form cellular modules, each with a specific function. These were designed to be placed on prepared concrete strip or piled foundations with segments assembled typically on a circular plan around a central atrium or courtyard, Fig. 2.15, to create a complete dwelling. An advantage of this modular system is that the dwelling could

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Fig. 2.15 ‘Bio-segment’ system of dwelling or living cells proposed by Michael Balz in January 1971. Reproduced from drawing by Michael Balz with permission from Michael Balz

2.6 A Future for Living Shells?

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Fig. 2.16 Alternative combinations and extension of the modular ‘bio-segment’ system. Reproduced from drawings by Michael Balz with permission from Michael Balz

be extended as the space demands of the family increase, Fig. 2.16. With suitable orientation, the open courtyard that is formed can be designed to have an enhanced micro-climate—to create a cooler shaded space in hot climates or a warm patio for plants in cooler climes. If formed into a complete circle, a fully sheltered and secure zone is created at the centre of the dwelling. More recently, in 1994, for a project in India, a more open segmental shell form was proposed for use in warm climates, Fig. 2.17 and a two-storey version, Fig. 2.18. The concept anticipates the current interest in offsite construction designed to rapidly deliver quality housing in large quantities. Factory manufacture of the units would allow them to be produced in all weathers, with a high-quality finish and services pre-installed. It also has the benefit of economies of scale. However, a limiting factor is that modules are constrained by the size that can be transported to site on public roads and/or for shipping overseas.

2.5.4 Isler ‘Bubble System AG’ The living vision of Geborgenes Wohnen heute und morgen and the modular ‘bio-segment’ system proposed by Michael Balz seem to have been ahead of their time. Nevertheless, in 1976, regrettably without the involvement of Michael Balz, Heinz Isler worked with Zürich architect Justus Dahinden on the development of pneumatically formed shells destined to be used for 3000 houses in the proposed new city of Moghan in Iran. When this project was cancelled due to political instability in Iran, Isler cofounded a company, Bubble System AG, with his favoured contractor Willi Bösiger AG, and partners Frutiger Söhne AG, Hans Schmid AG and François

Prouvost (Chilton 2000: 128; Boller and Beckh 2019). Following the construction of prototypes in the grounds of Isler’s office in 1977, the company promoted their cast in-situ modular ‘Bubble System’ for habitable small-scale concrete shells. These consisted of simple extended hemispherical domes somewhat similar to those developed in the 1940s by Wallace Neff—a hemispherical dome supported on slightly outward tapering walls of around 2 m in height and approximately 7 m diameter in plan. According to the publicity brochure, the standard modules could be combined in various ways to form larger units by, rather awkwardly, overlapping and merging adjacent domes. These modular shells were promoted as being suitable for dwellings, holiday homes, site accommodation, disaster relief housing, small offices, kiosks, etc. They were eventually employed for craft workshops near Paris, a motel and clubhouse in Switzerland and a motel in Saudi Arabia (Chilton 2000: 128–130). When compared to the Balz ‘bio-segment’ system, where from the outset the modular shell units were designed to be assembled into larger configurations, the resulting overall form of the ‘Bubble System’ does not approach the sculptural elegance of the organically flowing forms proposed by Michael Balz.

2.6

A Future for Living Shells?

Recent experiments with 3D printing of housing have opened up the possibility of shaping living shells directly without the use of formwork. Developed by World’s Advanced Saving Project (WASP) in collaboration with

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Fig. 2.17 Alternative ‘bio-segment’ system of dwelling or living shells for a warm climate. Reproduced from drawing by Michael Balz with permission from Michael Balz

34 Evolution/Organic Architecture

2.6 A Future for Living Shells?

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Fig. 2.18 Alternative two-storey ‘bio-segment’ system of dwelling or living shells. Reproduced from drawing by Michael Balz with permission from Michael Balz

36

Mario Cucinella Architects (Mario Cucinella Architects 2021), based in Bologna, the TECLA house, in Massa Lombarda, Italy, was printed using locally sourced soil materials. The two linked ribbed domed shells, which required 200 h of printing, using 7000 machine codes (G-code), placing 350 12-mm-thick layers, a total of 60 m3 of clay sourced from a local riverbed, are self-supporting and constitute the “structure, roof and cladding” (WASP 2021; Parkes 2021). As in the Balz House, described later in Chap. 4, where some internal features were, like the shell, cast in concrete, some furnishings of the TECLA house were also partly printed using locally sourced earth. However, non-conventional dwellings, such as the organic forms of reinforced concrete or GRP shells, have struggled to make an impact on the mass housing market. Due to the generally conservative nature of home buyers, banks and other mortgage providers are often reluctant to lend when they believe that a property may be difficult to sell if the buyer defaults on their payments. Although many indigenous buildings are of rounded womb-like form, modern builders and buyers are more familiar and more comfortable with, rectilinear construction. Those shell-form dwellings that have been built are usually individually commissioned to a specific design brief where some distinctive image is desired by a client with private finance. Another example of sustainable architecture that has also struggled to gain wide acceptance for dwellings is that of earth-sheltering. Despite the inherent benefits to be gained from the additional thermal insulation and thermal mass, few examples have been built. Here, there is a missed opportunity to amalgamate these benefits with the intrinsic strength of the shells derived from their efficient double curvature.

References Anon (1971) Port la Galère. In: Concrete quarterly, vol 91. Cement & Concrete Association, UK, pp 49–56. Available https://www.

2

Evolution/Organic Architecture

concretecentre.com/Publications-Software/Archive.aspx. Accessed 11 Aug 2022 Anon (2020) Bubble houses. Available https://99percentinvisible.org/ episode/bubble-houses/. Accessed 3 Nov 2020 Balz M (2011) Working with Heinz Isler. J Int Assoc Shell Spatial Struct 52(3):155–160 Balz M, Isler H (1968) Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden [Secure living today and tomorrow: new forms of housing—new construction methods] Baypren® (2020) Historical overview. Available https://baypren.com/ about-baypren/historical-overview. Accessed 18 Feb 2020 Boller G, Beckh M (2019) Building with air: Heinz Isler’s bubble houses and the use of pneumatic construction techniques. In: Campbell JWP, Baker N, Driver M, Heaton M, Kuban S, Tutton M, Yeomans D (eds) Proceedings of sixth conference of the construction history society, Cambridge, pp 494–506 Chilton JC (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford Ltd., London Heathcote E (1997) Imre Makovecz: the wings of the soul. Architectural monographs no 17. Academy Editions, Chichester Historic England (2017) Underhill. Available https://historicengland. org.uk/listing/the-list/list-entry/1440677. Accessed 7 July 2020 Isler H (1961) New shapes for shells. Bull Int Assoc Shell Struct 8: [Paper C-3] Los Angeles Conservancy (2020) Airform “bubble house”. Available https://www.laconservancy.org/locations/airform-bubble-house. Accessed 31 Dec 2020 Mario Cucinella Architects (2021) TECLA—technology and clay. Available https://www.mcarchitects.it/tecla-2. Accessed 10 May 2021 Parkes J (2021) Tecla house 3D-printed from locally sourced clay. Available https://www.dezeen.com/2021/04/23/mario-cucinellaarchitects-wasp-3d-printed-housing/?utm_medium=email&utm_ campaign=Daily%20Dezeen&utm_content=Daily%20Dezeen +CID_40b41f41e12327e79701792ff31104da&utm_source=Dezeen %20Mail&utm_term=Tecla%20house%203D-printed%20from% 20locally%20sourced%20clay. Accessed 10 May 2021 Perkin G (1970) Houses at castelleras. In: Concrete quarterly, vol 87. Cement & Concrete Association, UK, pp 20–25. Available https:// www.concretecentre.com/Publications-Software/Archive.aspx. Accessed 11 Aug 2022 Ramm E, Schunk E (2002) Heinz Isler Schalen: Katalog zur Ausstellung. Hochschulverlag AG an der ETH Zürich, p 111 Safdie Architects (2020) Habitat’67. Available https://www. safdiearchitects.com/projects/habitat-67. Accessed 3 Nov 2020 WASP (2021) TECLA. Available https://www.3dwasp.com/en/3dprinted-house-tecla/. Accessed 10 May 2021

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Built Shells

Abstract

Six thin reinforced concrete shell projects realized by Michael Balz in collaboration with engineer Heinz Isler are described in detail, namely: Zuschauer halle/kuppel (Auditorium), Theater unter den Kuppeln (Theatre under the Domes), Stetten auf den Fildern, near Stuttgart (1976). Naturtheater, Grötzingen, Aichtal, Germany (1977–78). Ballettsaal (Ballet Salon), Stetten (1979). Musical-Saal (Musical Salon), Stetten (1988–89). Europa-Park, in Rust (1992)—entrance canopies. Willi Bösiger SA, Langenthal, Switzerland (1992)—carport prototype. Chapter 4, which follows, is dedicated to the remaining project realized by the long-term collaborators, the Balz House, Stetten (1980), as this is of particular architectural, constructional and cultural interest.

3.1

Inspiration

Michael Balz first became interested in thin reinforced concrete shells when he became aware of, and was inspired by, Félix Candela’s hyperbolic paraboloid shells constructed in Mexico. This interest was further reinforced by his meeting Swiss engineer Heinz Isler at a conference in Stuttgart, in 1967, at a time when this form of construction was at its height. Despite their collaboration on the development of a number of unrealized projects, including a proposal for a dwelling house for Heinz Isler and his wife Maria adjacent to the Büro Isler studio in Lyssachschachen, near Burgdorf, Switzerland (described in Chap. 2), their first joint realized project was not until 1976, almost ten years after their first meeting, for an outdoor theatre at Stetten auf den Fildern, near Stuttgart, Germany.

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_3

3.2

Zuschauer Halle/Kuppel (Auditorium), Theater unter den Kuppeln (Theatre under the Domes), Stetten auf den Fildern, Near Stuttgart (1976)

The “Theater unter den Kuppeln” (Theatre under the Domes) was the first of what was originally intended to be five shells constructed on the same site, at Stetten auf den Fildern, near Stuttgart, see Fig. 3.1—although eventually only four were built. It came about for the following reason. In the Swabian region of south-west Germany there is a strong tradition of, predominantly amateur, outdoor theatre—the performance of plays, music and pantomime. Although already popular, in an effort to improve the comfort of the existing audience and to increase the numbers attending performances, it was proposed to provide spectators at Stetten auf den Fildern with some protection from adverse weather conditions. Planning restrictions for the site required that “…only buildings with organic appearance [are] allowed.” (Balz 2011). To comply with this stringent planning requirement and to minimize intrusion into the rural setting of the site, Michael Balz proposed a thin reinforced concrete shell, roughly triangular and of approximately 500 m2 in plan, labelled Zuschauer Kuppel in Fig. 3.1. Resembling a natural mound in the countryside, the shell has maximum plan dimensions of 27.2 m  22.0 m and a maximum rise of 7.5 m on the free edge, which faces an open-air performance space and stage. As can be seen from the site plan (top centre in Fig. 3.1) and the architectural model Fig. 3.2a, b, the free-form surface is symmetrical about one axis and rises from three supports, two slightly curved, relatively long bases at each side of the raked audience seating and a shorter base, also slightly curved, to the rear of the shell, the area where the lighting control panel was to be located.

37

Fig. 3.1 Site plan showing the complex of five Balz/Isler shells at Stetten auf den Fildern, near Stuttgart, as proposed in 1980. The basement plan of the ballet salon is shown to the right. The shell shown top right was never constructed. Reproduced from drawing by Michael Balz with permission from Michael Balz

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3.2 Zuschauer Halle/Kuppel (Auditorium), Theater unter den Kuppeln…

39

Fig. 3.2 a Plan view; and b elevational view from north-west of the architectural model of the Stetten site, excluding the Balz House. Reproduced from photographs by Michael Balz with permission from Michael Balz

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Fig. 3.3 a, b Gypsum plaster casts of the hanging models used to explore the potential geometry of the Theater unter den Kuppeln, Stetten, photographed in Heinz Isler’s studio. Photographs John Chilton with permission from the Isler family

To derive an appropriate and efficient geometry for the shell, engineer Heinz Isler used his tried and tested inverted hanging membrane technique. This method, which he introduced at the First Congress of the International Association for Shell Structures (now International Association for Shell and Spatial Structures), IASS, in Madrid, in 1959 (Isler 1961; Ramm and Schunk 2002; Chilton 2009) relies on the property of a flexible (bending-free) membrane to form a surface in pure tension when suspended under load. The three-dimensional geometry of this surface, can be captured, for instance, by using a layer of gypsum plaster of even thickness. When wet, the plaster layer applies a uniformly distributed load over the surface and, once the plaster has set, it can then be measured precisely. When inverted, this geometry theoretically produces a surface in pure compression under the same uniformly distributed applied loading. Thus, this method is ideal for form-finding of a thin reinforced concrete shell where the predominant load is its own weight—typically around 250 kg/m2 for a shell 100 mm thick—and the material is strong in compression. Isler’s hanging membrane form-finding technique can potentially generate an infinite number of alternative forms (Chilton 2010) depending on the boundary conditions existing at the time the surface becomes solid, for instance, the disposition and size of support points, size of the hanging membrane and membrane material used (woven cloth, rubber sheet, etc.). Each will be a theoretical compression surface when inverted and loaded only by its own weight, so the final selection of the form will depend on other factors such as architectural, aesthetic, and material economy considerations. Gypsum plaster casts of various hanging models used to explore the potential geometry of the Theater unter den

Kuppeln roof shell, produced at the Isler Studio, are shown in Fig. 3.3a, b. Once the preferred form has been selected, the plaster cast can be measured precisely to produce a set of x, y and z coordinates. To produce the geometry for construction of the full-scale shell, the as-measured model dimensions are scaled-up by the ratio between the maximum model and real structure dimensions. Figure 3.4 shows the main timber arched profiles being installed to define the shell on site. Where a reinforced concrete shell is used in a project, it often forms the dominant architectural statement and this is also true in this case. Because it is possible to generate an infinite number of possible solutions for the shell geometry when using the Isler inverted membrane technique, the selection of the preferred surface requires close collaboration between architect and engineer. By integrating the structural1 and architectural demands, the form and supporting structure of the Theater unter den Kuppeln shell was designed to provide a greater sense of enclosure than some of Heinz Isler’s other free-form shells, while offering an open uninterrupted view of the stage. This additional enclosure was in order to restrict disturbance of the audience during performances due to aircraft noise from the nearby Stuttgart Airport. Similarly, although not needed for thermal insulation in this situation, the wood–wool panels normally used as sacrificial formwork for the casting of the shell were

1 Recent research in the Isler archive, in Zürich, has revealed his hand calculations for this shell—just 12 pages.

3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78)

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Fig. 3.4 Main timber arched profiles being installed to define the shell form of the Theater unter den Kuppeln shell, Stetten. Reproduced from photograph by Michael Balz with permission from Michael Balz

left in place. Their absorbency improves the acoustics by moderating sound reflections and limiting any potential sound focusing from the curved shell surface (Chilton 2000). One of the key characteristics of thin concrete shells is that aesthetically they often appear more graceful when they are free-standing. That is when they are free of façades that tend to detract from their natural sculptural elegance. However, due to its situation, the relatively large extent of the supports and functional requirements, this is not necessarily apparent for this shell. Nevertheless, when viewed from the performance stage, Fig. 3.5, the shell reveals an elegant flowing arch with a slightly upturned edge. This lip provides the necessary resistance to potential buckling of the thin concrete surface, while channelling rainwater away from the free edge in front of the audience. The success of this shell—as substantiated by the increased audiences after its inauguration (Chilton 2000: 105)—led to a further commission for another shell to protect the audience for an outdoor theatre at Aichtal-Grötzingen using the same contractor Gustav Epple GmbH & Co. KG Bauunternehmung, Stuttgart.

3.3

Naturtheater, Grötzingen, Aichtal, Germany (1977–78)

Arguably the most dramatic and beautiful shell to result from the long collaboration between Michael Balz, as architect, and Heinz Isler, as engineer and “structural artist” (Billington 2003), is that realized as an open roof canopy for an outdoor theatre at Grötzingen, near Stuttgart, constructed in 1977–1978. Compared to the Theater unter den Kuppeln, Stetten, the free-standing shell of the Naturtheater Grötzingen benefits greatly from its location and is in poetic and physical harmony with its natural surroundings. It is also one of the few free-form shells engineered by Heinz Isler where the supports are at substantially different levels. Perched on a sloping site in woodland, the shell is approximately 600 m2 in plan, Fig. 3.6. It stands on five tapering supports located at three different levels on the slope and spans a maximum of 42 m on the free edge, which faces north towards the stage. The upturned arched

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Fig. 3.5 Flowing arch form of the Theater unter den Kuppeln shell, Stetten, as seen from the performance space. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

edge rises approximately 12.0 m from its springings, as seen in the front elevation, Fig. 3.7. Here, the open-air theatre is less subject to aircraft noise from planes taking off and landing at Stuttgart Airport so there is no need for the long enclosing side supports or partial glazing employed at Stetten. As a consequence of this, the situation in woodland, Fig. 3.8, and the minimal intrusion of the supports, the shell has a more refined gracefulness than is apparent in the Theater unter den Kuppeln shell.

3.3.1 Form-Finding of the Shell The initial architectural and structural concept for the roof form was developed by Michael Balz using thin hanging chains defining a series of catenaries—the form that a flexible chain adopts when hanging freely under its own weight. Once he was satisfied with the form aesthetically, he provided Heinz Isler with a wireframe model that described the geometry of the free edges, Fig. 3.9. This was used as the

basis for a template—the sloping plan cut from a board at scale 1:100, Fig. 3.10—from which the membrane could be suspended during the three-dimensional form-finding process. Based on this plan geometry, Isler produced a series of gypsum casts to determine the most elegant and efficient surface form. Importantly for this shell constructed on a steeply sloping site, Isler’s hanging membrane technique is easily adapted for supports at different heights. An example of one of the casts is shown in Figs. 3.11 and 3.12. The preferred model was measured precisely by Isler to determine the geometry required to set out the shell formwork. According to Michael Balz, the geometry of this final selected form was only slightly different (around 2%) from his initial proposal found with the hanging chain model. It is interesting to note here that the eminent scholar David Billington (1927–2018), who has written extensively about the work of Heinz Isler, had always believed that the form of the Grötzingen shell had been determined exclusively by Isler. He was astounded to hear directly from

Fig. 3.6 Plan of the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz

3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78) 43

Fig. 3.7 Front elevation and centre line section of the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz

44 3 Built Shells

3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78)

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Fig. 3.8 Naturtheater, Grötzingen shell blends into the surrounding woodland. Photograph John Chilton with permission from Michael Balz and Naturtheater, Grötzingen

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Fig. 3.9 Initial wireframe model for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family

Michael Balz at a dinner held in London, in 2011, during the IASS–IABSE Symposium—I was sitting next to David Billington at the time so can attest to his surprise—that it was he who had, in fact, proposed the initial form by adapting that used previously in Stetten.

3.3.2 Shell Construction Construction of the Grötzingen shell followed the process developed for Isler’s previous free-form shells. A key component of this is the design of the foundations. The individual shell springing points are connected by a system of reinforced concrete ground beams, Fig. 3.13, to form a closed “ring”, which is subsequently post-tensioned, once the shell concrete has acquired adequate strength. This foundation arrangement is designed to resist horizontal thrust from the shell, so that individual shell bases carry primarily vertical load. However, the ring has two other functions. Firstly, post-tensioning of the ring pulls the

individual shell supports inwards, which introduces compressive stresses into the shell surface. This compression closes micro-cracks in the concrete and improves its durability by reducing penetration of moisture and slowing carbonation, which can eventually lead to corrosion of the steel reinforcement. Secondly, the post-tensioning and drawing inwards of the supports lifts the shell surface, separating it from the formwork, thereby making this easier to remove. Once the foundations were complete, curved and profiled timber beams, supported on lightweight adjustable scaffolding, Fig. 3.14, were set parallel on grid lines. The curvature of each beam followed precisely the scaled-up geometry measured along the equivalent grid lines on the plaster form-finding model. As can be seen in Figs. 3.15 and 3.16, because they are supported on lightweight scaffolding, the beams themselves do not need to be continuous. Instead, they were assembled from discrete sawn profiled sections of up to 5 m in length, overlapped, nailed and screwed together to form the continuous shell curve. According to Michael Balz, this was cheaper than using

3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78)

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Fig. 3.10 Plan template for producing hanging membrane models for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family

bespoke glue-laminated beams. To produce the final double-curved surface, flexible timber laths were then laid at approximately 250 mm centres (Bösiger 2011) across the primary grid beams, Fig. 3.17. For a band of between 0.7 and 1.5 m width at the shell’s free edges and in areas adjacent to the supports where a fair concrete finish was desired, close boarding or plywood was used in place of the laths. Over the remainder of the surface, the spaced laths were then covered with a continuous layer of Heraklith wood– wool faced insulation slabs 500 mm wide and 2000 mm long (Bösiger 2011). This became the main surface against which the concrete shell was cast. As the weight of the shell and any applied load concentrates towards the supports, the shell thickness must be increased to maintain the concrete stresses at an acceptable level and to avoid instability due to buckling. This thickening can be identified in the increasing height of edge formwork, seen in Fig. 3.18. Another important detail can also be seen. As the wood–wool insulation stops short of the shell’s free edge in order to maintain a smooth soffit, the concrete of the shell is thicker—the normal shell thickness

plus the depth of the insulation slabs. In this way a wide but shallow, barely perceptible, edge stiffening element is ingeniously and skilfully incorporated into the shell form. Following placement of the steel reinforcement, concrete was placed using a skip, suspended from the on-site tower crane, Fig. 3.19. Here, the substantial steel reinforcement of the 42 m span, arched, upturned lip of the shell edge can be seen. The stiff arch and double curvature of the shell edge provide resistance against buckling of the free edge. Heinz Isler assessed the structural performance of the shells he engineered by using physical models2. However, following a site visit to Grötzingen in 2012, and discussions with Michael Balz, a group of students from Princeton University made an approximate assessment of the structural behaviour of the shell under its own weight using a very simplified numerical model with SAP2000 (finite element analysis (FEA) software) (Maurer et al. 2012). Taking into account the effect of the simplifications applied, this model

2 Recent research (Boller 2023), has revealed that this was supplemented by finite element analysis conducted by external consultants.

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Fig. 3.11 Plaster cast from one of the exploratory hanging membrane models for the Naturtheater, Grötzingen shell. Photograph John Chilton with permission from the Isler family

confirmed Heinz Isler’s contention that the surface was generally in compression, showed low stress levels in the centre of the shell and high compression in the main arch where the upturned edge—not modelled—provides buckling resistance.

3.3.3 Architectural and Aesthetic Considerations An important architectural and aesthetic consideration for thin concrete shell structures is an appreciation of their perceived rather than actual thickness (or thinness). This can usually only be based on the visible thickness at the free edges. Judged by this criterion, the extreme slenderness and delicate elegance of the Naturtheater, Grötzingen shell, without the intrusion of glazed façades, is self-evident, Fig. 3.20. Nevertheless, the main body of the shell is actually even more slender than it seems. This is because there is a small, non-structural, raised lip of 50 to 100 mm in height

along the free edges, seen in Fig. 3.21. Designed to direct rainwater to the roof drainage system at the supports, the raised lip, unfortunately, increases the perceived thickness. As mentioned previously, the permanent insulation board shuttering terminates between 0.7 m and 1.5 m from the edge of shell and is replaced by thinner plywood boards. Therefore, the concrete at the edge is actually thicker—between 140 and 190 mm including the drainage lip. However, over most of the surface the shell thickness is just 90 mm, increasing to 120 mm near supports (Chilton 2000: 105– 106), which translates to a maximum span to minimum thickness ratio of 467:1 for the majority of the shell surface. It should be noted that this shell, like the majority of Isler shells, has no additional waterproofing. Instead, it relies totally on the quality of the concrete, good surface compaction and the application of pre-stressing to maintain compression and thereby minimize surface cracking and resist rainwater penetration. This results in a considerable cost saving. As can be seen in Fig. 3.21, with time, the initially bright white shell surface seen in Fig. 3.20 takes on

3.3 Naturtheater, Grötzingen, Aichtal, Germany (1977–78)

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Fig. 3.12 Plan view of plaster cast shown in Fig. 3.11. Photograph John Chilton with permission from the Isler family

a surface patina of moss and lichens, which help the structure to blend easily into the natural environment, appearing like a grassy mound or large moss-covered rock arch among the trees. For better acoustic conditions for the audience at theatrical performances, like the first shell canopy constructed at Stetten, the wood–wool slabs were left in place to reduce unwanted sound reflections under the completed shell and to improve audibility of the performers. However, there is another interesting acoustic characteristic of the shell itself. In August 2010, with Michael Balz and Ekkehard Ramm, I scaled the Naturtheater shell by clambering up its slippery south-facing support. Once we reached its summit, Michael encouraged us to stamp our feet hard, which stimulated a deep resonating sound like the ringing of a very large bell. This response is a consequence of the shell’s extreme slenderness and a testament to the integrity of the uncracked thin

reinforced concrete surface. Further evidence of the strength and stability of the elegant shell form designed by Michael Balz and Heinz Isler is that, shortly after completion, it survived unscathed a strong earthquake of magnitude ML = 5.7, which occurred near Albstadt in the Swabian Jura (approximately 60 km south of Grötzingen), on the 3 September 1978 (Haessler et al 1980; Balz 2011: 159). The shell is still in excellent condition more than 40 years after its construction. Michael Balz’s original plans included three unobtrusive and well-placed rings of lights—as can be seen in the plan Fig. 3.4—in order to illuminate the theatre seating. These are somewhat reminiscent of the circular rooflights that are generally included in Heinz Isler’s ‘bubble’ shells. However, theatrical productions require a wide variety of stage lighting and, with time, the front edge of the shell has accumulated an array of spotlights, which, although every effort has been

3

Fig. 3.13 Arrangement of the foundations and ground beams for the Naturtheater, Grötzingen shell. Reproduced from drawing by Michael Balz with permission from Michael Balz

50 Built Shells

3.4 Ballettsaal (Ballet Salon), Stetten (1979)

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Fig. 3.14 Lightweight adjustable scaffolding supports the shell falsework and formwork. Michael Balz (facing camera) and Heinz Isler are in discussion in the foreground in February 1978. Reproduced

from photograph by Michael Balz with permission from Michael Balz, the Isler family and Naturtheater, Grötzingen

made to minimize their intrusion, tend to intrude and slightly detract from the clean curve of the 42-m span shell arch, Fig. 3.22.

conceived by Michael Balz has no symmetry3. Therefore, it presented a new and fascinating challenge to both architect and engineer. As appropriate for the freely sketched form, Heinz Isler used his inverted hanging membrane method to determine the shell geometry and, as has been mentioned previously, the preferred version of the gypsum plaster cast had to be measured precisely. Figure 3.24 shows the model for this shell with grid lines and measurement points marked on the surface. It can be observed that the cast gypsum model is slightly larger than the perimeter of the proposed shell that has been drawn on its surface. Isler’s method of suspending a weighted point to determine the z-coordinate (height) of the model shell surface to an accuracy of 0.01 mm for specified points on an x-y coordinate grid becomes less accurate as the inclination of the surface increases—it becomes more difficult to position the point precisely in the x-y plane. There are also small variations in texture of the gypsum surface that affect accuracy. Therefore, generally, the density of measurement points is

3.4

Ballettsaal (Ballet Salon), Stetten (1979)

The second shell to be constructed at the Stetten cultural complex was the Ballettsaal (Ballet Salon), completed in 1979. Developed from a conceptual model, scale 1:100, produced by Michael Balz, the free-form shell of approximately rhomboidal plan sits over a basement supported on one extended curved continuous base, radius 20.25 m, and two short isolated bases, as can be seen bottom centre in Fig. 3.1. Taking into consideration the same environmental design constraints that applied to the Theater unter den Kuppeln, the thin organic shell form limits the volume of material required in construction of the building envelope and minimizes the enclosed volume to reduce heating costs, while providing open glazed façades primarily to north and west elevations to capture natural daylight, Fig. 3.23. This shell is notable because, unlike the majority of the free-form shells engineered by Heinz Isler, the shape

3

Recent research in the Isler archive, in Zürich, has revealed that an earlier proposal was for a 16 m x 16 m, square plan, Isler shell, similar to that built in 1972 at the Hotel Splendide Royal, Lugano.

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Fig. 3.15 Curved primary beams assembled from discrete sawn profiled sections follow the geometry measured along grid lines on the hanging membrane models for the Naturtheater, Grötzingen shell.

Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen

increased near the supports where, due to its greater inclination, the surface is more difficult to measure accurately. Correct definition of the shell profile in these areas is extremely important. Due to the concentration of load towards the supports, compressive stresses increase in the shell and this can induce buckling unless the thickness is increased appropriately. At the thin edges, also, an accurately specified double curved profile is required to stiffen the surface to avoid buckling. Isler’s drawing, dated 22 March 1979, giving the setting out dimensions for the edge profiles (where there is also more curvature) for the binders (Bindertabelle) supporting the surface formwork of the Ballettsaal shell is shown in Fig. 3.25. The two sections Schnitt (Section) A-A (top left) and Schnitt (Section) B-B (top right) illustrate how the insulation board used as permanent shuttering terminates at a cast-in element used to attach the glazed façade. They also reveal how the shell thickness increases as it merges into the

foundation and how it thins slightly towards the free edge. Here, as in all the free-form shells, there is a small upstand to control rainwater runoff and a drip detail to reduce rain staining of the soffit of the shell edge. Figure 3.26 shows the heights for shell support (Höhe für Schalenschalung) on Isler’s drawing SB452/28 dated 21 March 1989. This drawing is shown here for completeness, although it actually relates to the main body of the Musical-Saal, constructed in 1988–1989, which is described in Sect. 3.5. The geometry of the two shells is exactly the same but is mirrored, as in this drawing. Roughly pencilled contour lines sketched at 0.5 m intervals reveal a relatively flat area at the crown of the shell. This is also apparent in Schnitt Achse (Section Axis) 14, to the right in Fig. 3.26, where internal heights are also indicated. At the time of construction of these shells, Michael Balz was sworn to secrecy never to reveal the geometry given in Isler’s drawings. During his life, Heinz Isler was very protective of the geometry of his shells to avoid—what he

3.4 Ballettsaal (Ballet Salon), Stetten (1979)

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Fig. 3.16 Heinz Isler is the central figure carrying out a site inspection of the Naturtheater, Grötzingen shell falsework. Reproduced from photograph by Michael Balz with permission from Michael Balz, the Isler family and Naturtheater, Grötzingen

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Fig. 3.17 Flexible timber laths at approximately 250 mm centres laid across the primary grid beams to generate the double-curved surface derived from the hanging membrane models for the Naturtheater, Grötzingen shell. Note the continuous boarding near the support in the

foreground where a fair-faced finish is required. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen

feared would be—potentially inferior copies being built without his knowledge or permission. However, this information is now publicly available at the Heinz Isler Archive at the Institute for the History and Theory of Architecture (Institut für Geschichte und Theorie der Architektur (gta)) at the Swiss Federal Institute of Technology (Eidgenössische Technische Hochschule (ETH)) Zürich. Construction of the shell by contractor Gustav Epple GmbH & Co. KG Bauunternehmung, Stuttgart, followed a similar procedure to that of the two theatre shells, with a

system of profiled timber binder beams erected on lightweight adjustable scaffolding, Fig. 3.27. Fair-faced plywood shuttering can be seen along the shell edges where the underside will be exposed outside the finished building envelope. Following installation of the flexible laths, three of which can be seen draped across the binders where they reveal the profile of the shell along section lines, insulation slabs were installed. The pattern they make can be seen clearly in Fig. 3.28 as well as the junction boxes from which lighting

3.4 Ballettsaal (Ballet Salon), Stetten (1979)

Fig. 3.18 Formwork and reinforcement at the north-west shell base. Note the areas at the shell edge and the inclined leg where no insulation slabs have been placed, thus forming a wide but shallow edge stiffening

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element. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen

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Fig. 3.19 Placing of the shell concrete. Note the heavy steel reinforcement in the slightly thickened shell edge. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen

3.5 Musical-Saal (Musical Salon), Stetten (1988–1989)

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Fig. 3.20 Elegant slender form of the Naturtheater, Grötzingen shell shortly after completion. The shell is actually thinner than it appears because there is a small non-structural lip or upstand at the edges to

direct rainwater off the shell. The maximum span to minimum thickness ratio is 467:1. Reproduced from photograph by Michael Balz with permission from Michael Balz and Naturtheater, Grötzingen

fittings (seen in Fig. 3.23) will eventually be suspended. The bottom layer of steel reinforcement is being fixed in the thicker edge sections. In Fig. 3.29, the general steel reinforcement layout can be seen—two orthogonal layers over the main surface with additional reinforcement in the edge strips and radiating from the bases—also the wiring ducts for electrical connections to the lighting are visible. The gradual progress of concrete pours is exposed by the different colours across the shell surface, seen in Fig. 3.30. The last area of the shell to be concreted was the steeper face down to the long base. In this part, the concrete was sprayed onto the formwork before finishing with hand tools —compaction and surface smoothing including forming the drainage upstand along the free edges, Fig. 3.31. This is perhaps an appropriate point to emphasize the material economy that accompanies the sculptural qualities, Fig. 3.32, of this and the other realized shells. Over the majority of the surface, this shell is just 80 mm thick, thinner than a typical ground floor concrete slab in a house, while spanning approximately 20 m. This means that a 5.0 m3 truck load of concrete is sufficient to cast around 60 m2 of the shell surface.

In this case, ultimately, the shell covered a fully enclosed architectural space. However, the sympathetic façade glazing, set back by approximately 900 mm from the free edges, allows the flowing organic form of the shell to be fully appreciated, Fig. 3.33. Over the forty years since the Ballettsaal shell was constructed, it has acquired a surface patina of lichens, allowing it to blend effortlessly into the surrounding vegetation and comply with the local planning requirements, Fig. 3.34.

3.5

Musical-Saal (Musical Salon), Stetten (1988–1989)

In 1988–89, a similar shell was constructed by contractor Himmel Bau KG, Echterdingen, as shown in the final plan of the Stetten cultural centre, Fig. 3.35. To the north-east of the site, the sheltering shell for the outdoor theatre ‘Zuschauer Kuppel’ (top, centre) faces an open-air stage ‘Freilicht Bühne’, which is embraced by a conventional backstage building containing workshops, prop storage and changing rooms. The Ballettsaal (bottom, centre) is linked to the Musical-Saal (bottom, left) by a foyer and cafeteria. As a

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Fig. 3.21 Architect Michael Balz at the thin edge of the Naturtheater, Grötzingen shell indicating the small raised lip provided to channel rainwater to the drainage system at the supports. Note the natural

3

Built Shells

surface patina of moss and lichens. Photograph John Chilton with permission of Michael Balz and Naturtheater, Grötzingen

3.6 Europa-Park, in Rust (1992): Entrance Canopies

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Fig. 3.22 Unobtrusive rings of auditorium lighting contrast with the array of spotlights, which tend to intrude and slightly detract from the clean curve of the 42-m span arch of the front shell edge. Photograph John Chilton with permission of Michael Balz and Naturtheater, Grötzingen

multi-purpose space, the Musical-Saal (Musical Salon) is used for meetings and rehearsals. Although similar in size and form to the Ballettsaal, the later shell is a mirrored version. On site, it is also rotated anti-clockwise by an angle of 35 degrees about the intersection of axes projected along the east and west façades of the Ballettsaal and the south-west facing façade of the new Musical-Saal. The thin edge of the Musical-Saal roof is very apparent in Fig. 3.36, where it can clearly be seen that the shell thickness increases gradually towards the support in the foreground, as seen in the Schnitt (Section) B-B shown in Fig. 3.25. In this building, only the upper half of the south-east-facing façade is glazed, with the lower half being occupied by doors that open out onto a garden/festival space to expand the music room if required. In the interior view, Fig. 3.37, the organic sweep of the shell is fully exposed. The upper frame of the metal-framed glazing is concealed behind the ceiling insulation and separates this from the external bare concrete. All three shells are connected by the flat-roofed foyer/ cafeteria, which incorporates branching organic tree-like

columns, Fig. 3.38, also seen internally in Fig. 3.39, with the theatre shell behind. Figure 3.36 also highlights the architectural challenge of connecting more conventional rectilinear construction to a building of organic form. Here the conflict has been resolved sympathetically by forming the connection in the vertical north-facing façade, in such a way that the shell roof and cafeteria roof construction are separate and connected only by glazing. Thus, the heavier, more traditional, form is visually separated from the thin organic shell.

3.6

Europa-Park, in Rust (1992): Entrance Canopies

In Europe, the construction of reinforced concrete shells had gradually waned since the 1970s, so the examples described above can be considered exceptions. Nonetheless, since the construction of the Musical-Saal shell, Michael Balz has continued to promote the use of architectural shells and has constructed some examples at smaller scale.

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Fig. 3.23 Interior of the Ballettsaal (Ballet Salon) shell, Stetten auf den Fildern. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

Europa-Park is a leisure park at Rust, about 40 km south of Strasbourg, close to the River Rhine and near the border between France and Germany. Here, entrance canopy shell forms, on a square plan, were developed for the Eisstadion (ice stadium) in the Greek themed area at Europa-Park, by Michael Balz’s son Markus, a structural engineer familiar with the techniques used by Heinz Isler, and modelled manually at a scale of 1:20 (Balz 2011), Fig. 3.40. This was one of the few occasions when there was a minor disturbance of the close working relationship between Michael Balz and Heinz Isler. When Heinz Isler was consulted, he seemed slightly disappointed commenting “Why didn’t you ask me? Why are you asking Markus?”. However, after a minor correction of the geometry harmony was restored and Isler said “… fine go make it” (Balz 2018).

Michael Balz also recalls long discussions with the contractor Willi Bösiger SA as to how best to create the supporting legs of the shell. Bösiger was of the opinion that half-pipes could be used for the lower part of the shell but eventually special precast sections were made (Balz 2018). The upper part of the shells was then formed in situ with sprayed concrete on purpose-made and reusable timber formwork with “…reinforcement […] woven over the wooden formwork using a four-edge system which enables an optimal adaption to the organic shape.” (Balz 2011), as seen in Fig. 3.41. The join between precast and in situ areas of the shell can plainly be seen in the final shell form, Fig. 3.42. Subsequently, in 1995, at the same location, similar but larger (unbuilt) shells were proposed to enclose a replica of the Soviet/Russian space station Mir. Figure 3.43 shows Michael Balz’s design for an 11.5-m-high tripartite open exhibition space on three supports. Spanning around 14 m

3.7 Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992)

Fig. 3.24 Model used to precisely determine the Ballettsaal shell geometry showing the grid lines along which Heinz Isler measured the coordinates of points on the plaster cast and the perimeter of the

between bases, the shells cantilever 8 m from the bases extending approximately 16 m in total from the mid-point of the structure. A more extensive solution to cover the same exhibit is shown in Fig. 3.44. On four bases and symmetrical about one axis, this shell has a maximum span of 40.8 m, only slightly shorter than the 42 m span of the Grötzingen shell, see Sect. 3.3. In this case, the shell is pulled upwards at the centre to accommodate an inclined rooflight, which is circular in plan.

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proposed shell that has been drawn on its surface. Photograph John Chilton with permission of the Isler family

3.7

Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992)

Construction of the Europa-Park canopies demonstrated the benefits of repetition and the possibility of the adoption of modular shells as a means of cost reduction—excessive cost being cited as one of the reasons that reinforced concrete

Fig. 3.25 1:50 scale plan showing the setting out geometry for the edge profiles of the Ballettsaal shell—Heinz Isler’s drawing SB321/22 dated 22 March 1979. The relationship of the insulation used as sacrificial shuttering and the shell can be seen in the sections. Reproduced from drawing by Heinz Isler in the possession of Michael Balz, with permission of Michael Balz and the Isler family

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Fig. 3.26 Heights for shell support (Höhe für Schalenschalung) on Heinz Isler’s drawing SB452/28 dated 21 March 1989. These are for the main body of the mirrored version of the same geometry, as used for the Musical-Saal, constructed in 1988–1989. Note the contours at 0.5 m intervals sketched approximately in pencil. Reproduced from drawing by Heinz Isler in the possession of Michael Balz, with permission of Michael Balz and the Isler family

3.7 Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992) 63

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Fig. 3.27 Profiled binder beams and draped flexible laths define the Ballettsaal shell geometry. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

shells have become less popular in developed countries since their peak in the 1950s and 60s. This led to the development of a partially prefabricated prototype carport, Fig. 3.45, of approximately 6 m  6 m, in collaboration with Willi Bösiger SA, from Langenthal, Switzerland. As with the canopies developed for EuropaPark, the lower supporting ‘leg’ elements, seen in close up in Fig. 3.46, were all precast while the roofing element was produced in situ using sprayed concrete. For those who wanted to stand out from their neighbours, the carport was marketed as the ‘BBI High Tech Carport’ from Bösiger AG. It offered a shapely, stable shell concreted on site by specialists, on prefabricated formwork. Alongside protection for two cars, the carport’s benefits were

advertised as including cost-effective construction, low maintenance costs, long service life and a hail-proof and accessible roof. Although the prototype was initially proposed as a covered carport, it was recognized that there is clearly potential for the same elements to be utilized for many alternative applications, for instance, for low-cost housing or shelters for disaster relief. The current shells are formed in reinforced concrete. However, similar structural units could equally be thermoformed and used to create highly insulated lightweight mass-produced habitable units, Fig. 3.47. Such prefabricated lightweight shell modules have considerable potential in today’s emphasis on off-site production of housing.

3.7 Carport Prototype Developed with Willi Bösiger SA, Langenthal, Switzerland (1992)

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Fig. 3.28 Shell preparation for concreting with insulation slabs used as permanent shuttering in place and the bottom layer of steel reinforcement in the edge sections. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

Fig. 3.29 General placement of steel reinforcement in two layers over the insulation slabs. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

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Fig. 3.30 Different coloured zones reveal the progress as concrete is gradually placed across the shell from the individual bases towards the long base edge. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

3.8

Reflection

This chapter has revealed the variety of reinforced concrete shells designed and realized by Michael Balz that range in size from the 42-m maximum span for the outdoor theatre at Grötzingen, recognized as one of the most elegant free-form shells engineered by Heinz Isler, to the prototype partially prefabricated, 6-m span carport developed with Willi Bösiger SA. The concreting time for the Stetten and Grötzingen shells once their foundations had been completed was a

maximum of between 8 and 10 h—in Grötzingen this required a team of 10 workers. This contributed to the affordability of producing the stable sculptural shells with only prestressing forces in the shell. Michael Balz believes that an important success of this method is that all these shells he and Heinz Isler built in this way are absolutely waterproof without any additional surface protection! As he remarks, the Zuschauer halle, theatre auditorium, at Stetten is now over 42 years old and has not needed any maintenance. He has also pointed out that the building costs for all of these shells, realized by constructed companies in

3.8 Reflection

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Fig. 3.31 Hand tool finishing of the sprayed concrete on the long base steepest face of the Ballettsaal shell. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

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Fig. 3.32 Extreme thinness, typically just 80 mm, and sculptural qualities of the shell can be fully appreciated before the façades are installed. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

Fig. 3.33 Sympathetic north façade glazing of the Ballettsaal shell, set back from the free edge as seen from the Balz House. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

3.8 Reflection

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Fig. 3.34 Over the last 40 years the surface has acquired a patina of lichens and blends effortlessly into the surrounding vegetation. Photograph John Chilton with permission of Michael Balz and Theater unter den Kuppeln

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Fig. 3.35 Final plan of the Stetten cultural centre. Reproduced from drawing by Michael Balz with permission from Michael Balz

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3.8 Reflection

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Fig. 3.36 Musical-Saal shell, viewed from the rear of the Theater unter den Kuppeln, with the linking cafeteria to the right. Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln

southern Germany, were comparable with prices for conventionally shape concrete buildings. Otherwise, their realization would not have been possible, as the clients were private theatre clubs, with limited budgets (Balz 2021). Nevertheless, these shells have been built at a time when this form of construction was out of favour in Europe and are a tribute to Michael Balz’s unwavering advocacy of their application.

However, one very significant shell designed and constructed by Michael Balz has been deliberately omitted from this chapter: that is the house that he built for himself and his family at Stetten in 1979–80, located bottom left in Fig. 3.35. Given its innovative architectural design and social significance, as recognized by its listing in 2017 as a cultural monument in the Federal State of Baden-Württemberg, it is appraised in detail in the following chapter.

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Fig. 3.37 Interior view of the Musical-Saal shell shows the organic sweep of the insulated surface which conceals the upper frame of the metal-framed glazing. Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln

Fig. 3.38 Cafeteria/foyer building with organic tree-like columns linking the three shells. The Musical-Saal shell is just visible (left) and theatre shell (right). Photograph John Chilton with permission from Michael Balz and Theater unter den Kuppeln

3.8 Reflection

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Fig. 3.39 Internal view of the foyer with the theatre shell behind. Reproduced from photograph by Michael Balz with permission from Michael Balz and Theater unter den Kuppeln

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Fig. 3.40 Scale model of entrance canopy for Europa-Park developed by Michael Balz’s son Markus Balz. Photograph John Chilton with permission from Markus Balz

3.8 Reflection

Fig. 3.41 Reusable timber formwork with “…reinforcement […] woven over the wooden formwork using a four-edge system which enables an optimal adaption to the organic shape.” (Balz 2011) for one

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of the entrance canopy shells for the Eisstadion (ice stadium) in the Greek themed area at Europa-Park. Reproduced from photograph by Michael Balz with permission from Michael Balz and Europa-Park

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Fig. 3.42 Completed entrance canopy shell for Europa-Park. Reproduced from photograph by Michael Balz with permission from Michael Balz and Europa-Park

3.8 Reflection

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Fig. 3.43 Shell design for an exhibition space to enclose a replica of the Soviet/Russian space station Mir, at Europa-Park. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 3.44 Alternative proposal for an exhibition space to enclose a replica of the Soviet/Russian space station Mir, at Europa-Park. Reproduced from drawing by Michael Balz with permission from Michael Balz

3.8 Reflection

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Fig. 3.45 Partially prefabricated prototype carport, 6 m  6 m, in collaboration with Willi Bösiger SA: (top) development model; (middle and bottom) outside the company’s offices in Langenthal, Switzerland. Photographs top and middle Reproduced from photographs by Michael Balz with permission from Michael Balz; bottom photograph: John Chilton

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Fig. 3.46 Precast base element of the partially prefabricated prototype carport. Photograph John Chilton

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References

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Fig. 3.47 Proposals for modular low-cost housing using thermoformed insulated shells. Reproduced from drawing by Michael Balz with permission from Michael Balz

References Balz M (2011) Working with Heinz Isler. J Int Assoc Shell Spatial Struct 52(3), No. 169:155–160 (Madrid, IASS) Balz M (2018) Recorded conversation with John Chilton at the Balz House, Stetten auf den Fildern, 5 June 2018 Balz M (2021) Private communication, 18 Aug 2021 Billington D (2003) Heinz Isler: structural art in thin-shell concrete. In: The art of structural design: a swiss legacy. Princeton University Art Museum, Yale University Press, pp 128–162 Boller G (2023) The model as a working method: Heinz Isler’s experimental approach to shell design. Diss. ETH No. 28878 Bösiger H (2011) The building of Isler shells. J Int Assoc Shell Spatial Struct 52(3), No. 169:161–172 (Madrid, IASS) Chilton J (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford, London Chilton J (2009) 39 etc...: Heinz Isler’s infinite spectrum of new shapes for shells. In: Lázaro C, Domingo A (eds) Proceedings of the international association for shell and spatial structures (IASS)

symposium 2009, evolution and trends in design, analysis and construction of shell and spatial structures. Editorial de la UPV (Universidad Politécnica de Valencia), Valencia, pp 51–62. Available http://hdl.handle.net/10251/6465. Accessed 13 Nov 2020 Chilton J (2010) Heinz Isler’s infinite spectrum: form-finding, in design. Architect Des Spec Issue: New Struct: Des Eng Architect Technol 80(4):64–71 Haessler H, Hoang-Trong P, Schick R, Schneider G, Strobach K (1980) The September 3, 1978, Swabian Jura earthquake. Tectonophysics 68(1–2):1–14 Available https://doi.org/10.1016/0040-1951(80) 90005-0). Accessed 13 Nov 2020 Isler H (1961) New shapes for shells. Bull Int Assoc Shell Struct 8: [Paper C-3] Maurer T, O’Grady E, Tung E (2012) Inverse hanging membrane: the Naturtheater Grötzingen, evolution of German shells: efficiency in form. Available http://shells.princeton.edu/Grotz.html. Accessed 13 Nov 2020 Ramm E, Schunk E (2002) Heinz Isler Schalen: Katalog zur Ausstellung. Hochschulverlag AG an der ETH Zürich, p 111

4

Balz House, Stetten auf den Fildern Leinfelden-Echterdingen, Near Stuttgart (1980)

Abstract

The Balz House is one of a group of reinforced concrete shells constructed at Stetten auf den Fildern, LeinfeldenEchterdingen, near Stuttgart. Its design follows from the explorations by Michael Balz into new forms of living, as described earlier in Chap. 2. Although it is just one of his built shells, a separate chapter is devoted to this organic architectural form as it represents an exemplar of a fully integrated family living environment, which also used construction that was highly innovative for the time (1979/80). The house also contains Michael Balz’s architectural studio. In 2017, the Balz House shell was classified as a cultural monument in the Federal State Baden-Württemberg, as it is believed to be unique in the region and is considered an exemplar of constructive optimization and an organically secure environment providing a blueprint for modern living.

4.1

Introduction

Many people have the ambition to design and build their own house but for architects this aspiration is usually even stronger, as it offers them the opportunity to put their design philosophy into practice, unconstrained by a client’s brief. Coincidentally, at around the same time as the Balz House was being built, 1979–80 (Chilton 2000; Ramm and Schunk 2002), I was designing and building my own house. Having, a couple of years earlier, visited friends in Denmark who

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_4

were in the process of having a new house built, I had become aware of how much more advanced house construction was in that country at that time, when compared to building regulations then in force in the UK—especially in terms of thermal insulation, airtightness and ventilation requirements. Some people, myself included, were already beginning to be concerned about anthropological effects on the environment. With that in mind, despite the local planning constraints necessitating a building of conventional appearance—natural stone for the external walls and clay tiles for the roof—I decided to future-proof the construction somewhat by including a high level of thermal insulation in the building envelope, a level which has only recently been obligatory according to building regulations in the UK, almost 40 years later. In the design of his own house, Michael Balz also recognized the need for a high level of energy performance of the building envelope but was able to take the design at least one step further. Because of the existing reinforced concrete shells on the site, it was actually a planning requirement that the house should be of a non-conventional organic form in order to relate to the prevailing architectural context. Having previously made proposals for shell-form dwellings—in the brochure Geborgenes Wohnen heute und Morgen: neue Wohnformen—neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing—New Construction Methods)—and for a bespoke shell-formed house for his collaborator Heinz Isler and his wife Maria (see Sect. 2.5.2), he took the opportunity to assimilate these designs and modify them to accommodate the requirements of his own young family, Fig. 4.1.

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Fig. 4.1 The Balz House viewed from the north-west. The shell appears to hover above the ground. Reproduced from photograph by Michael Balz with permission from Michael Balz

84 Balz House, Stetten auf den Fildern Leinfelden-Echterdingen …

4.5 Construction: Forming the Shell

4.2

First Encounter

I first met Michael and Eva Balz in Copenhagen in 1991, where we had adjacent hotel rooms, while attending the IASS Symposium “Spatial Structures at the Turn of the Millennium”. Michael was presenting a paper “Living and Dwelling Structures for a New Century” (Balz and Seidel 1991) in a session devoted to the ‘Design of Form’, which showed his own house as an example. On learning that they lived in this ‘flying-saucer’-like reinforced concrete shell at Stetten auf den Fildern, near Stuttgart, I was immediately hooked and hoped to have the opportunity to experience it for myself one day. That opportunity came in May 1993 when I was attending an unrelated technical meeting in Stuttgart. Having a window seat on the flight from Birmingham, and recalling that the Balz House was located close to Stuttgart Airport, I specifically looked out for it as we made our approach before landing. My luck was in, as the flight passed almost directly over the Stetten site, by chance, the cloud parted and the group of shells, house included, was clearly visible from the window. On landing, I called Michael Balz and he very kindly invited me for dinner that evening. Despite it being a rather dull cloudy day, as we approached the house it appeared as a striking, slightly alien, form in the landscape: that is alien in the sense that it was not representative of the typical architecture of the locality, although it blended very comfortably with its immediate neighbours, the Theater unter den Kuppeln and Ballettsaal shells, both constructed in the 1970s, and the Musical-Saal shell constructed after the house, in 1988–89, see Chap. 3. Because the terrace surrounding the shell cantilevers out over the ground floor, which is clad in dark-stained timber, it cast a shadow such that the white painted structure above appeared to hover above the ground.

4.3

Finding the Form

The shape of the free-form reinforced concrete shell that forms the distinctive outline of the Balz House was determined by measurement of a plaster cast taken from a 1:20 scale inflated balloon model (Balz 2011). A PVC membrane was formed—by air pressure from below and heat applied from above to increase its elasticity—through a ‘cloverleaf’shaped template, Fig. 4.2, which followed the proposed floor plan. Small inflated balloons inserted into cut-outs in the initial cast were then used to form cantilevered shell projections to stiffen the edge of the openings. Figure 4.3 shows the resulting architectural concept model.

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4.4

Accommodation

Having a maximum span of 17 m, the shell covers approximately 95 m2 and is raised on an open, approximately elliptical landscaped terrace deck, which has upturned edges. The whole is supported on 145 m2 of ground floor accommodation of more conventional geometry—encompassing the entrance hall, Michael Balz’s office, a sculptor’s studio for his mother and bedrooms for his children and visitors. When entering the house at the lower level, light percolates from above into the entrance hall. On taking a tight spiral stair, one emerges into a very different, almost magical cave-like world—a large, mainly organically shaped, open-plan, living space under the curved shell roof. The layout of the upper floor and plan of terrace that forms the roof of the lower floor is shown in Fig. 4.4. To the right of the stairs, an approximately circular living/ relaxation area (A) is top lit by a large, circular, northfacing rooflight and has open views to the west though a vertical glazed façade. To the left, the open-plan kitchen and breakfast bar (C) and dining area (B) are top lit by a south-facing rooflight and embrace a fireplace (F) available for supplementary winter heating. To the rear is the master bedroom (D), which again is top lit by a rooflight directly over the bed, to give views of the night sky, and includes an en-suite bathing grotto (E). All living areas have unrestricted access to the sheltered external west-facing terrace (G), which provides an additional informal dining area in summer. There is a further storage platform above the kitchen area, seen top centre in the section, Fig. 4.5. At the time of construction, this could only be accessed by a vertical ladder which has since been replaced by a more secure small spiral stair, see Fig. 4.11. This platform offers views to the south and a bird’s eye panorama of the open-plan living area. Apart from the walls and door enclosing the toilet, there are no internal partitions interrupting the open volume enclosed by the shell.

4.5

Construction: Forming the Shell

Due to financial constraints at the time the house was constructed in 1979–80, it was not possible to fully complete it before occupation. Initially, the Balz family lived in just the ground floor rooms while the open-plan accommodation under the shell was being finished. From the foundations to the finished shell structure took approximately 8 months (excluding a break of around 6 weeks during the winter). The fit out of the shell was carried out

Balz House, Stetten auf den Fildern Leinfelden-Echterdingen …

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Fig. 4.2 Template following the proposed Balz House floor plan at 1:20 scale used to produce an inflated PVC membrane form by air pressure from below and heat applied from above to increase its

elasticity. Reproduced from photograph by Michael Balz with permission from Michael Balz

over a period of about ten months, as funds permitted— around four months before it was possible to move in and a further six months for final finishing including kitchen, furnishings and carpets. This was not accomplished alone but, as Michael Balz’s children Angelika, Johannes and Markus recall, was achieved with the generous assistance of friends and family (Balz et al. 2020), who were only too

happy to contribute to the finishing of the inspiring pioneering living environment. When Michael Balz first introduced his ‘living’ shells in the late 1960s, the proposed method of construction was to spray insulation material or concrete onto reusable inflated formwork. Apparently, there were prototype large inflatable formwork ‘balloons’ of 3–4 m diameter at the previous Balz

4.5 Construction: Forming the Shell

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Fig. 4.3 Concept model of the Balz House derived from modelling with an inflated PVC membrane at 1:20 scale. Reproduced from photograph by Michael Balz with permission from Michael Balz

residence, which his children used to play on with their friends, like the ‘bouncy castles’ popular for children’s parties today (Balz et al. 2020). However, instead of defining the complex shape of this shell with an inflated membrane, which would have required precise calculation of the cutting pattern to manufacture the membrane formwork and strict control of the inflation pressure to ensure that the required shell form was achieved and maintained, for the Balz House an alternative method was used. With advice from Heinz Isler, as engineer for the project, and the contractor Krahn GmbH & Co. KG Bauunternehmen, Stuttgart, the shell form was initially defined by building a steel reinforcement cage with individual bars following the curvature of the shell, as shown in sketches, Fig. 4.6. This cage was supported on a number of curved timber arches and the steel window frames, Fig. 4.7. According to Michael Balz, Heinz Isler’s detailed construction drawings indicated that the reinforcement mesh should be woven ‘organically’ from individual bars (Balz 2011). This made it easier to create the double-curved shapes than by deforming standard square or rectangular reinforcement mesh sheets. To correspond with

the unique design, the window frames had to be made specifically for the project and this was carried out by the local blacksmith. The primary shell reinforcement was then covered with a denser, lightweight, easily deformable mesh, Fig. 4.8, in preparation for receiving the sprayed concrete, which was finished by trowelling to give a smooth surface, Fig. 4.9. In Fig. 4.10, the concreting of the upper shell can be seen with the concrete being placed by skip suspended from a tower crane. The low-slump concrete mix is being compacted around the steel reinforcement using a poker vibrator prior to hand-finishing of the surface. Initially, the option offorming the shell as a sandwich of polyurethane foam insulation faced with reinforced polyester was considered for the Balz House. However, eventually, the more conventional alternative of a reinforced concrete shell was adopted. Taking advantage of the mass of the concrete, this allowed the shell to be employed as a large solar thermal collector, with the thermal insulation applied to the inner surface. The conventional reinforced concrete slab of the open terrace is paved with a pervious block paviour system (see Figs. 4.20 and 4.21). Rainwater percolates through the

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Fig. 4.4 Plan of the Balz House, Stetten, showing: A: main living/relaxation area; B: dining area; C: kitchen and breakfast bar; D: master bedroom; E: bathing grotto; F: fireplace/chimney; G: external terrace. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 4.5 Long section through the Balz House, Stetten, showing the additional storage/viewing platform above the kitchen (centre), accessed by a ladder, and more conventional accommodation below. Reproduced from drawing by Michael Balz with permission from Michael Balz

4.5 Construction: Forming the Shell 89

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Fig. 4.6 Sketches showing proposed layout of individual steel bar (rather than welded mesh) reinforcement following the curvature of the shell. Reproduced from drawings by Michael Balz with permission from Michael Balz

90 Balz House, Stetten auf den Fildern Leinfelden-Echterdingen …

4.6 The Interior

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Fig. 4.7 Steel reinforcement formed over curved timber beams and the steel window frame to the left. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 4.8 (left) Lightweight mesh is attached to the main steel reinforcement and seen in close up in the background (right). Reproduced from photographs by Michael Balz with permission from Michael, Eva, Johannes and Angelika Balz, Walter and Werner Steck

substrate to the waterproofing layer applied to the upper surface of the supporting concrete slab. It is then discharged, well away from the ground floor timber cladding by drainage pipes that pierce the slab at regular intervals.

4.6

The Interior

It is important to stress that the interior architecture was also designed and constructed by Michael Balz. Mass-produced furniture is generally intended for use in living spaces with

rooms where the walls are straight, vertical and arranged on a rectilinear plan. These are conditions that certainly do not apply within most of the upper living areas of the Balz House, where walls curved in both plan and section spring from the floor slab and merge seamlessly into the ceiling. Basic furniture items that would normally be bought and simply arranged in vacant rooms had, here, to be specially designed and fabricated as built-in elements from the outset. Taking advantage of the inherent mouldability and sculptural properties of concrete, Michael Balz opted to freely model several interior features

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Fig. 4.9 Compaction and hand-finishing of the low-slump concrete placed on the lower shell, in 1979. Reproduced from photograph by Michael Balz with permission from Michael Balz

from this compliant plastic material—for instance, the breakfast bar and kitchen, and platform above, Fig. 4.11—to harmonize with the curves of the shell form. Similarly, applying his design skills and experience gained during his carpentry apprenticeship to the task of furnishing the main living area, he built bespoke furniture. An impressive example is the integrated seating that incorporates multiple storage units concealed behind the upholstery, which follow the rounded curves of the shell, Fig. 4.12. It is a tribute to the high quality of materials and his skilled craftsmanship that the original bespoke furnishings are still in use, 40 years later. Apparently, the purple covering material—a colour fashionable in the early 1980s—was chosen by Michael, uncharacteristically, without reference to his wife Eva. She initially disapproved but through familiarity eventually came to accept the vibrant colour (Balz et al. 2020). Rooflights inserted at well-chosen locations in the shell offer enticing external views and ensure that the interior is flooded with natural light during the day. In the late afternoon and evening, sunlight streams through the west-facing glazed façade that adjoins the sheltered terrace accessed from the living area and fills the shell with a warm glow. At

night, the rounded form of the light-painted shell interior provides a perfect reflective surface to diffuse and distribute light from multiple sources, including a pendant lamp hanging from a custom-built curved wood arm, which forms a sculptural feature in the seating area as it cantilevers from a tailored shelving unit, shown in detail in Fig. 4.13.

4.7

Keeping It Warm: The Thermal System

The Balz House needs very little heating in the conventional sense. Environmental and economic considerations were paramount in the design of the innovative heating system, which is based on using much of the building envelope as an extensive solar thermal collector. Energy use had become a serious concern in the 1970s due to the oil crises of 1973—caused by an oil embargo resulting from the Yom Kippur War—and again in 1979 with the reduction in oil production resulting from the revolution in Iran. As can be seen in the post-construction ‘as-built’ schematic drawing detailing the energy capture and heating system, Fig. 4.14, 20-mm-diameter polyethylene pipes are looped

4.7 Keeping It Warm: The Thermal System

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Fig. 4.10 Placing by skip suspended from a tower crane and compaction of the upper shell. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 4.11 Organic form of kitchen, breakfast bar, upper platform and fireplace (to right) all moulded from concrete. Reproduced from photograph by Michael Balz with permission from Michael Balz

through the concrete of the shell, terrace deck and its upturned parapets to capture heat from the surfaces warmed by the sun, Figs. 4.14 and 4.15. This low-grade heat is then concentrated using a heat pump and stored in the lower foundation slab, which also warms the soil beneath. When required, a separate system of 20-mm-diameter polyethylene pipes circulates warm water to the floor slabs, internal and external walls and solid concrete fixed interior moulded features. This distribution system is similar to, but more extensive than, a contemporary underfloor lowtemperature heating system. Even the base and sides of the mosaic tiled bath in the bathing grotto, Fig. 4.16, are effectively warmed by the sun! To minimize heat loss from the building envelope, 100 mm of Styrofoam insulation is provided on the interior surface of the shell. This has an internal aluminium vapour barrier to avoid the formation of condensation on the inside of the concrete shell, which is covered by plaster and paint finish. The same level of insulation is positioned under floor slabs and on the exterior face of the concrete blockwork ground floor walls. These are finished with a dark-stained,

vertical, timber-board cladding. Detailing of insulation around window and door openings is designed to minimize cold bridging and condensation risk adjacent to the metal frames. Figure 4.17 shows how the perimeter of the metal-framed glazing is fully concealed externally by the shell at their junction and by insulation internally. A high level of thermal inertia is provided by the concrete mass in the ground floor slab, internal partitions, externally insulated walls and the slab and moulded concrete features of the first floor. This is beneficial for the passive control of the internal thermal environment (Szokolay 2004: 57). It means that, even if heating is not continuous, these elements are slow to cool and tend to remain warmer than the air temperature in the room. In summer, excess absorbed heat can be discharged to the ground under the house, which allows some limited inter-seasonal storage. This can then be extracted by the heating system pipes, as required. According to contemporary reports (Anon 1982), the 1980–81 season heating cost, which mainly consists of electricity for the heat pump, was only 10 DM per m2 of floor area.

4.8 Thermal Comfort

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Fig. 4.12 View of interior of the upper shell from the upper platform with original bespoke furnishing covered with purple fabric. Reproduced from photograph by Michael Balz with permission from Michael Balz

4.8

Thermal Comfort

Thermal comfort of building occupants is affected by several factors but, usually, the most significant are the dry-bulb air temperature (DBT) and the effect of radiation interchange between the body and the surrounding surfaces, measured as the mean radiant temperature (MRT) by a thermometer within a black-painted ball suspended at the centre of the room. The environmental or resultant temperature, that which is effectively experienced by the resident, is some combination of the two measured temperatures, typically ranging from a ratio of 2:1 (MRT:DBT) in a warm environment when wearing light clothing to 1:1 (MRT:DBT) in a cooler situation with heavier clothing (Szokolay 2004: 17–18). In the Balz House, because the walls and floors are warmed in winter the occupants are hardly radiating any of their body heat to cooler walls. This is unlike the situation that normally occurs in more conventional houses, where walls are unheated. Under the shell, the surface area in question is also lower

than if there had been vertical walls and a horizontal ceiling. Hence, the mean radiant temperature is high in the Balz House, so the family feels warmer, even at room dry-bulb air temperatures that may be lower than normally encountered in living accommodation in Germany. This contributes to the feeling of cosiness experienced when in the building. Consequently, energy demand for space heating is reduced. In summer, this effect may be reversed. The unheated mass of the concrete, insulated from the external summer heat, remains cooler than the air, so the environment feels fresher. In theory, the heating system could be operated in reverse, extracting heat from the walls and floor under conditions of extreme summer temperatures, such as those being predicted by future climate scenarios. Hence, a high level of thermal comfort can be maintained all year round using, almost exclusively, solar energy. The concept of heated walls was also applied in the UK at about the same time in the Grade 2 listed, Alexandra Road Estate, in the London Borough of Camden, which was designed by architect and RIBA Gold Medallist, Neave

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Fig. 4.13 Custom-built shelving and pendant lamp support arm by Michael Balz to the left. Late afternoon sun fills the seating area. Reproduced from photograph by Michael Balz with permission from Michael Balz

Brown (1929–2018), and completed in 1979. There, the system did not work so efficiently. The residents of the social housing complained of overheating as they had no individual control over the heating system. This was not a problem encountered in the Balz House.

4.9

Durability

An inflated PVC membrane was used for the form-finding of the Balz House shell. Because the surface under internal pressure is in pure tension, a rigid surface of precisely the same form would be in pure compression, if subjected to reversed loading (external pressure) of the same intensity. Such a shape is ideal to be cast from concrete, a material that is strong in compression but weak in tension. This reversed loading condition is approximately, but not exactly, reproduced by the self-weight of the concrete shell, which acts vertically under gravity rather than pressure which acts perpendicular to the balloon surface. The effect of the difference in direction of application of the load is relatively small but sufficient to induce some bending in the surface, as well as the compression. This requires light steel reinforcement to

avoid cracking. A recent structural study by students at Princeton University revealed that both tensile and compressive stresses in the shell were low and well within the permissible values for the concrete (Mehrotra et al. 2013). The quality of the design, materials and workmanship of the Balz House shell are confirmed by the fact that, 40 years after construction, it is undamaged and shows no cracks, Fig. 4.18. Mechanical systems are not so durable, and it is commonly anticipated that heating and ventilation equipment will require replacement approximately every 15–20 years. The heat pump is coming to the end of its useful life and the cost of electricity powering it has increased considerably since the 1980s. Hence, there is some discussion about a potential replacement. In this respect, the house’s listing as a cultural monument (see Sect. 4.11) makes any change more difficult, as alterations of the external appearance require approval. One possible solution would be to instal solar photovoltaic panels on the terrace surrounding the shell to power a new, possibly more efficient heat pump using a renewable energy source. Michael Balz has already prepared a sketch of a possible arrangement.

Fig. 4.14 Schematic post-construction drawing showing details of the solar thermal energy capture and low-temperature heating systems inserted in the concrete elements of the shell, deck, floors, walls and other thermally massive interior features. Reproduced from drawing by Michael Balz with permission from Michael Balz

4.9 Durability 97

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Fig. 4.15 Twenty-mm-diameter polyethylene pipes are looped through the shell to capture heat from the concrete warmed by the sun. Shown here during construction before adding the outer concrete layer. Reproduced from photograph by Michael Balz with permission from Michael Balz

However, the installation of panels on or near the house might attract objections. In justification, it might be argued that this would be fully in accord with one of the original design objectives, to create an energy-efficient dwelling. Nevertheless, Michael Balz’s preferred solution would be to apply flexible photovoltaics, for instance organic photovoltaic (OPV) cells similar to those used in the German pavilion for the Milan Expo 2015, directly onto the shell surface.

4.10

Living in the Balz House

I have visited the Balz House on a number of occasions and have stayed there overnight a few times. Each time I visit— and I’m sure I’m not alone in this view—I find myself being totally enchanted and fascinated by the cave-like form of the open-plan living space. It is actually akin to being transported to the inside of some giant sculpture. For me, the ambiance of the bulbous volume under the shell feels extremely homely and welcoming, like a warm embrace. However, the perception of a guest is not necessarily the same as that of a long-term resident. Therefore, to gain more insight into the positive (and perhaps negative) aspects of living in the Balz House I talked to Michael Balz’s children —Johannes, Markus and Angelika—who lived through the construction of the house and spent their formative years in

that non-conventional setting. Until 1980, they had lived in a conventional house and all of them do so today. So, they are in a perfect position to compare the contrasting qualities of the different living environments. From our conversations, it is clear that all three are tremendously proud of their father’s achievement, which, they emphasize, he accomplished despite limited financial resources. They recall ‘Familien Konferenz’—family conferences to discuss whether a summer holiday could be afforded or whether spending on completion of the house was the highest priority. Also, while growing up they were very aware that they lived in a special home, quite distinct from the conventional houses of their school friends. All three have very positive memories of growing up in the house and the warm and comfortable environment that it afforded. However, there was some debate about whether this feeling of comfort was engendered more by the well-heated environment created by the innovative heating system, with warm floor, walls and fixed furnishings than the enfolding cave-like shape of the main living spaces (Balz et al. 2020). They recall playing in the upper platform, which is used as a space for quiet relaxation or for a spare bed for visitors, Fig. 4.19. At the time, this was only accessible via a vertical ladder, which has since been replaced by a more secure spiral stair with handrail.

4.11

Architectural and Social Significance

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Fig. 4.16 Through heating pipes embedded in the walls and base the bathing grotto is effectively warmed by the sun! Reproduced from photograph by Michael Balz with permission from Michael Balz

A recurring theme during our conversations was how, despite the house being physically quite remote from the town, right from the time of its construction and first occupation, it was an exceptionally hospitable home and the setting for frequent social events, and still is. It would seem that the open-plan living space, with external dining space, Fig. 4.20, and the extensive oval terrace that surrounds the shell, onto which it opens, Fig. 4.21, serves as an absolutely wonderful place to hold parties!

4.11

Architectural and Social Significance

The architectural and social significance of the Balz House shell is undeniable. This was recognized in January 2017 when it was incorporated in the list of cultural monuments by the Landesamt für Denkmalpflege (State Office for the Preservation of Historical Monuments) of BadenWürttemberg. To quote from the official listing sent to Michael Balz when informing him of this decision:

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Fig. 4.17 Metal-framed glazing is fully concealed externally by the shell at their junction and by insulation internally. Photograph John Chilton with permission from Michael Balz

Das Wohnhaus Balz ist ein Beispiel für den Schalenbau, der in den 1960er und 1970er Jahren eine Blütezeit erlebte, für organische Wohnarchitektur, aber auch für die Suche nach alternativen, ökologischen, zukunftsorientierten Wohnformen Ende der 1970er Jahre. Mit seinem Schalendach in organischen Formen ist es nach bisherigem Kenntnisstand einzigartig im Wohnbau in Baden-Württemberg. Das Gebäude ist aus wissenschaftlichen (architekturgeschichtlichen) und künstlerischen Gründen ein Kulturdenkmal gemäß §2 Denkmalschutzgesetz Baden-Württemberg. An seiner Erhaltung besteht aus exemplarischen und dokumentarischen Gründen sowie wegen seiner Singularität ein öffentliches Interesse. (Landesamt für Denkmalpflege 2017)

This translates as: “The Balz residence is an example of shell construction, which experienced a heyday in the 1960s and 1970s, of organic residential architecture, but also of the

search for alternative, ecological, future-oriented forms of living in the late 1970s. With its shell roof of organic forms, it is, according to current knowledge, unique in residential architecture in Baden-Württemberg. For scientific (architectural–historical) and artistic reasons, the building is a cultural monument in accordance with §2 of the Baden-Württemberg Monument Protection Act. There is a public interest in its preservation for exemplary and documentary reasons and because of its singularity.” (Translation by author) It is important to note that this mark of distinction was not bestowed solely because the shells of the Balz House are considered an exemplar of constructive optimization in reinforced concrete but also because the organically secure family environment it provides is regarded as a realization of

4.11

Architectural and Social Significance

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Fig. 4.18 External surface of the shell in June 2018 is still well preserved after almost 40 years. Photograph John Chilton with permission from Michael Balz

the blueprint for modern living outlined by Michael Balz in his pamphlet Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden (Balz and Isler 1968). Presenting a striking new residential architectural form, in many ways the house anticipates the current social and interior design vogue for open-plan living, with linked kitchen, dining and relaxation spaces. It provides for a live/work environment—with the incorporation of Michael Balz’s architectural office and a sculpture studio for his late mother on the ground floor—thereby avoiding the need for

daily commuting. It also provides accommodation for three generations to live together in an atmosphere of mutual support. From the technological point of view, it also offers practical achievable solutions to the current challenge of reducing global energy consumption—both embodied and operational energy—to control emissions of carbon dioxide (CO2) and other gases that are leading to anthropologically induced climate change, and to exploit renewable energy sources wherever possible.

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Fig. 4.19 Upper platform used as a space for quiet relaxation has a panoramic view of the open living room below, to the right. Reproduced from photograph by Michael Balz with permission from Michael Balz

4.12

Embodied Energy

Because bending is avoided and compressive stresses dominate, the generally 100–150-mm-thick (Balz 2011), double-curved form of the shell enfolding the upper floor is structurally very efficient. For instance, it is much thinner and requires less steel reinforcement than a flat concrete slab of equivalent span and loading. The organic architectural form minimizes the volume of construction materials—concrete for the shell, insulation and plaster—required to enclose the living space. Additionally, the main living accommodation effectively fills roof space that would normally be empty or just used for storage in more traditional houses. Together, these savings result in a reduction in the embodied energy required for the Balz House’s manufacture.

4.13

Operational Energy

The sculptural shape of the shell has a lower surface area than a rectilinear building envelope of similar floor area. It also has more aerodynamic contours. This results in a smoother, less turbulent, airflow around the structure, which tends to reduce the cooling effect of the wind. Both of these

characteristics help to minimize heat loss from the building envelope in winter. Warm air rises. From my own experience of living in a well-insulated two-storey dwelling, I can corroborate that in such houses the air temperature on the upper floor can often be 2–3 °C warmer than at the lower. However, it is usually recommended that bedrooms are heated to a lower temperature than the main living accommodation in a house. Consequently, by taking the decision to locate most bedrooms on the cooler ground floor, rather than the more conventional location on the upper floor, and to situate the living spaces occupied during the day on the warmer first floor, further energy efficiencies resulted. The innovative heating system circulates low-temperature warm water through tubes embedded in the walls and floors on the lower floor. Although there is no automatic thermostatic control of room temperature, it is possible to manually control the heating circuit in each room. Warmed air may rise via the spiral stair and augment heating at the upper level. The aperture occupied by the spiral stair—the only opening between the floors—is relatively small. Hence, in winter, when windows and doors mostly remain closed, thermal stratification can occur with little vertical air

4.13

Operational Energy

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Fig. 4.20 Michael Balz on the west-facing roof terrace adjacent to the sheltered external dining space in June 2018. Photograph John Chilton with permission from Michael Balz

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Fig. 4.21 The extensive external terrace on the south side of the shell—ideal for parties. Photograph John Chilton with permission from Michael Balz

movement between floors. The upper living area is comfortably warm and the lower floor cooler. Since the 1980s, attitudes to the environmental impact of buildings have gradually developed. There are additional opportunities to reduce the environmental footprint of the Balz House that might be incorporated today. The terrace around the shell is covered with hard paving. To blend more naturally and ecologically into the rural setting today, one might replace at least part of this with some form of green roof. This would preserve its utility as a social space while potentially creating a natural habitat for wild flowers and insects and slowing rainwater run-off. That rainwater could then be collected and reused. There is less opportunity to exploit solar energy for electricity generation without compromising the aesthetics of the sculptural shell form. Perhaps photovoltaic panels could be incorporated over part of the deck as a canopy or to create a greenhouse for food production.

4.14

Final Thoughts…

Since its construction, the Balz House has attracted a lot of attention in the media with articles in newspapers, magazines and technical journals and, more recently, television features (SWR Fernsehen 2021) and video on the Internet (Bauen and Wohnen 2020; SWR Fernsehen 2020). Given the architectural distinction, Figs. 4.22, 4.23 and 4.24, and undeniable social and environmental benefits that the house presents, it is rather surprising that similar dwellings have not been built. Is this due to cost? Or is it because of some inherent conservatism of urban planners, house builders or house buyers? One can easily imagine housing developments of the future where such dwellings, with the ground floor perhaps fully or partially earth-sheltered to further reduce their environmental impact, form unobtrusive shell clusters in the landscape.

4.14

Final Thoughts…

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Fig. 4.22 Distinctive organic architecture of the Balz House viewed from the south-west. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 4.23 South elevation of the Balz House showing kitchen and platform over. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 4.24 Snow clinging to the shell surface of the Balz House reveals the high quality of the insulated building envelope. Reproduced from photograph by Michael Balz with permission from Michael Balz

References Anon (1982) Haus und Gehäuse: Hausgruppe am Naturtheater Stetten auf den Fildern, Beton-Prisma 43–82. Bundesverband der Deutschen Zementindustrie, Betonverlag Düsseldorf, Düsseldorf, pp 1–8 Balz M (2011) Working with Heinz Isler. J Int Assoc Shell Spat Struct 52 (3)(169):155–160 Balz M, Isler H (1968) Geborgenes Wohnen heute und morgen: neue Wohnformen—neue Baumethoden [Secure living today and tomorrow: new forms of housing—new construction methods]— pamphlet Balz M, Seidel J (1991) Living and dwelling structures for a new century. In: Wester T, Medwadowski SJ, Mogensen I (eds) Spatial structures at the turn of the millennium. Proceedings of the international IASS symposium, vol 2. Kunstakademiets Forlag Arkitektskolen, Copenhagen, pp 19–26 Balz A, Balz J, Balz M (2020) Recorded conversation with the author, 1 May 2020 Bauen and Wohnen (2020) Außergewöhnlich wohnen im Architektenhaus | Das UFO-Haus | Wohngeschichte [Exceptional living in an architect’s house | The UFO house | Living history], 4 Oct 2020. Available https://www.youtube.com/watch?v=CCUMNRqDvtc. Accessed 25 June 2021

Chilton J (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford, London, pp 130–134 Landesamt für Denkmalpflege (2017) Liste der Kulturdenkmale in Baden-Württemberg Teil A1: Begründung der Denkmaleigenschaft [List of cultural monuments in Baden-Württemberg part A1: justification of the status as a monument], 20 Jan 2017 Mehrotra A, Richardson V, Siu S (2013) Balz House. In: Evolution of German shells: efficiency in form. Available http://shells.princeton. edu/Balz.html. Accessed 1 July 2021 Ramm E, Schunk E (2002) Heinz Isler Schalen. Hochschulverlag an der ETH, Zürich SWR Fernsehen [SWR Television] (2020) Organisches Wohnen: Futuristisches Haus in Stetten auf den Fildern [Organic living: futuristic house in Stetten auf den Fildern], 6 Mar 2020. Available https://www.youtube.com/watch?v=BF1w8az3Jsw. Accessed 25 June 2021 SWR Fernsehen [SWR Television] (2021) Das Ufo-Haus von Stetten [The UFO house of Stetten]. Transmitted Friday, 30 Apr 2021 at 18:45, Landesschau Baden-Württemberg. Available https://www. swrfernsehen.de/landesschau-bw/das-ufo-haus-von-stetten-100. html. Accessed 25 June 2021 Szokolay SV (2004) Introduction to architectural science: the basis of sustainable design. Architectural Press, Oxford

5

Competitions

Abstract

Selected competition entries by Michael Balz are reviewed including for an Evangelical Lutheran church (1967), the German National Museum of Contemporary History in Bonn (1985) and for the German Pavilion at Expo’2000 in Hanover.

5.1

Introduction

Architectural competitions provide an opportunity for designers to present novel and stimulating visions for clients who are often looking for unconventional solutions or for striking, potentially iconic, forms. Sponsors of the competition hope that the novel architecture of the building will become associated in the mind of the public with the image they wish to create for their organization or company. The infinite spectrum of dramatic three-dimensionally curved forms that can be realized with thin reinforced concrete shells offers the architect an exhilarating palette with which to respond to the competition brief. Michael Balz has expressed the view that nature and landscape demand large organic forms and that shells are the most fundamental means to enclose architectural spaces. Shell forms have been a constituent of the natural environment since time immemorial. They have existed in nature since long before the human race evolved, or began to build shelters and differentiate between walls, roofs and ceilings. Certainly, they have existed since long before people had the idea of declaring their own rectilinear “four walls” as a symbol of what was desirable. During their heyday, from the 1950s to the 1970s, reinforced concrete shells were seen as offering such striking solutions, as is amply demonstrated by the internationally renowned churches and chapels designed by Félix Candela, in Mexico, for example, the Iglesia de la Virgen Milagrosa

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_5

(Church of Our Miraculous Lady), Narvarte, 1954–55; the Capilla de Nuestra Señora de la Soledad—El Altillo (Chapel of Our Lady of Solitude), 1955 and Iglesia de San José Obrero (Church of St. Joseph the Labourer) Monterrey (1959) both in collaboration with architects Enrique de la Mora and Fernando Lopez Carmona (Faber 1963). These shells were all based on Candela’s astonishing mastery of the mathematically definable geometry of the hyperbolic paraboloid (or ‘hypar’). However, since their peak, shell structures have struggled to maintain their popularity and prevalence. It is often suggested that this is due to the cost of construction—the need for complex double-curved formwork for the concrete, for instance—but it is also greatly influenced by the move to more transparent building envelopes, since the 1970s, despite the difficulties with energy management that this may present. In defiance of this change in architectural trend, since 1967, Michael Balz has proposed a series of dramatic shell forms in response to competition briefs, but, unfortunately, without success. Unlike Candela, Michael Balz’s designs display more organic, free-forms derived from his experimentation with physical models. The first example, an Evangelical Lutheran church, in Heilbronn (1967), uses forms based on his earlier experimentation with inflated membranes. However, having visited Heinz Isler’s design office in 1967, he would have been exposed to the results of Isler’s other shell form-finding techniques, using the inverted hanging membrane, for instance (Isler 1961; Chilton 2009). This was at the time when Isler was actively designing some of his most iconic free-form shells using this method—the motorway service station roofs at Deitingen Süd (1968) and the Sicli SA factory (1969), in Geneva (Chilton 2000; Ramm and Schunk 2002). The hanging membrane offers a continuum of unconventional, structurally efficient, shell forms: hence, the remaining competition designs all feature forms derived using this technique.

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5.2

5

Evangelical Lutheran Church, Heilbronn (1967)

The first competition entered independently by Michael Balz was for a Protestant church and ecclesiastical community centre in Heilbronn, in 1967. As can be appreciated from the international renown of the religious buildings designed by Candela and his collaborators, such edifices can offer an ideal opportunity for the imagination of the architect to be given relatively free rein and create highly expressive structural forms. A preliminary sketch titled ‘Kirche mit Nebenräumen’ (church with side rooms), dated 8th October 1967, Fig. 5.1, shows a glazed shell-domed main entrance, with outdoor space to the left sheltered by a curved shell wall, two small shells as meeting/social rooms to the right and a pierced sculptural tower behind. Another sketch, titled ‘Sakralbau in Schalenbauweise’ (sacred building in shell construction) on the same date, Fig. 5.2, appears to show an alternative with three nested and sculpted shells and, again, a conspicuous inclined and pierced tower. The shells are all derived from the pneumatic formfinding that had been used to develop the Urschalen and living shells. It is apparent that, at the time these proposals were made, Michael Balz had already met Heinz Isler, as he is credited as construction consultant on the drawings. The detailed plan of the final competition entry, Fig. 5.3, shows the main volume of the church, bottom left, which is able to accommodate approximately 300 worshippers, seated roughly concentrically around the altar, placed directly beneath the dramatic shell tower. On the primary axis, there is a smaller chapel/assembly space. To the bottom right, an external space for outdoor community events and performances is screened from sight and protected from wind by a double-curved shell wall. The remaining three volumes are multi-purpose rooms that are the same size and shape so that they can all be formed with the same inflated formwork. This concept is clearly developed from the system proposed for construction of the living shells, described in Chap. 2. Reinforced concrete shells are double-curved, threedimensional forms, and it is difficult to appreciate the relationship of architectural spaces purely from two-dimensional plans, elevations and section drawings. Therefore, the physical model is crucial for the better understanding, appraisal and full appreciation of the spatial and architectural qualities of the scheme, Figs. 5.4 and 5.5. From the model, it can be seen that the main worship space and secondary chapel are integrated under the curves of a single free-form shell roof that will create a distinct atmosphere of congregation, tranquillity and community within. This roof shell merges with the base of the tower and the curved shell wall that defines and protects the exterior

Competitions

community area. Internally, the remaining multi-purpose shells offer a tangible sense of security and sanctuary due to their ovoid shape. These and other ancillary accommodation are linked under an intermediate flat roof. In the elevational view of the model, Fig. 5.5, the final form of the tower is more smoothed than it appears in the preliminary sketches. It is reminiscent of a petal from an orchid flower, Fig. 5.6. Informed by Michael Balz’s study of three-dimensional curved forms in nature, the tower shell gathers and reflects daylight down into the body of the church, illuminating the altar from above, through an opening piercing the main shell. For ease of construction, it was proposed to cast the whole tower form in a horizontal position, lying on the ground, to be raised up later and connected to the church roof shell. The image of the model within a wooded landscape, Fig. 5.7, suggests the dramatic impact that the shells would have engendered if built. Sadly, this was not to be. Michael Balz recalls that, at the time, there was considerable discussion about whether such predominantly domed shell forms were appropriate for an Evangelical Lutheran Christian place of worship. Some theologians argued that the shells were too Islamic, and this may have influenced the rejection of the proposal. This is despite magnificent domes crowning Christian cathedrals, such as Santa Maria del Fiore, Florence (1436), St. Peter’s Basilica, Rome (1626) and St. Paul’s London (1710) and shells of various forms having been used for churches in other parts of the world in the 1950s and 1960s, e.g. hyperbolic paraboloid shells for the Iglesia de la Virgen Milagrosa, Church of Our Miraculous Lady, Narvarte, Mexico City (1954–55), by Félix Candela (1910–1997), St. John the Divine, Lincoln, UK (1962–3) by architect Sam Scorer (1923–2003) and the Sekiguchi Catholic Church, St. Mary’s Cathedral, Tokyo (1964) by Kenzo Tange (1913–2005).

5.3

Haus der Geschichte der Bundesrepublik Deutschland (German National Museum of Contemporary History), Bonn (1985)

5.3.1 Introduction A competition for a public building such as a museum presents a perfect opportunity for the architect to propose a dramatic building form that will potentially become an icon that will attract visitors through the novelty of the architectural form as well as the museum exhibits. Well-known examples are the spiral-ramped form of Frank Lloyd Wright’s Solomon R. Guggenheim Museum in New York, completed in 1959, and Frank Gehry’s Guggenheim Museum, in Bilbao, completed in 1997. The latter

Fig. 5.1 Preliminary sketch of church with side rooms, dated 8th October 1967, for the competition entry for an Evangelical Lutheran church, in Heilbronn. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.2 Preliminary sketch of sacred building in shell construction, dated 8th October 1967, for the competition entry for an Evangelical Lutheran church, in Heilbronn. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.3 Plan of final competition entry. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.4 Plan view of presentation model for final competition entry. Note the piercing of the roof shell that allows the altar to be illuminated by light reflected downward from the curving tower shell. Reproduced from photograph by Michael Balz with permission from Michael Balz

contributed to the regeneration of the city. In that instance, at least, the architecture is perhaps more recognizable than the contents of the museum! Possibly with the desire to conceive an iconic building in mind, in 1985, Michael Balz, in partnership with architect Johannes Fritz from the Institute for Lightweight Structures, and with Heinz Isler as advisor for engineering and construction, developed an entry for a two-stage, open and nationwide, architectural design competition for a highprofile museum of contemporary German history, in Bonn, on a site previously occupied by a restaurant and car dealership. The competition was organized by the German Federal government, as a result of a declaration of 13th October 1982 by the then Chancellor Helmut Kohl. Soon after taking office, he proposed that a collection recording

German history since 1945, the end of World War II in Europe, should be instituted, in Bonn (Kohl 1982). With the experience gained from the design and construction of the Naturtheater, Grötzingen, in 1977–78, Michael Balz was confident that it would be possible to build his proposal, which included four large striking free-form shells. He recalls that he and Johannes Fritz started with a brainstorming session, discussing the brief and playing with little bricks to represent the volumes of accommodation specified “…for a laugh”. Then, suddenly they made a breakthrough “Wow! In this surrounding there should be a demonstration of culture. Shells could be good”. They then started to form the accommodation bricks into terraces and planned it so that the individual shell shapes above would reflect the functions that were positioned below (Balz 2018).

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Fig. 5.5 Model of the final competition entry showing the relationship of the tower to the main shell and linking of ancillary shells with the flatroofed terrace. Reproduced from photograph by Michael Balz with permission from Michael Balz

5.3.2 Shell Roofs As Johannes Fritz recalls, they wanted the history of the new “free Germany” to be exhibited in an equally “free-form architecture” (Fritz 2021). Consequently, this was one of the key design drivers. Experimenting with Heinz Isler’s hanging membrane technique of shell form-finding, together they developed a remarkable roof for the museum. Four shell segments, each of different shape and size, were arranged around a central courtyard, like petals round the stem and ovaries at the centre of a flower. The curvature of the freeform shells is revealed in Fig. 5.8. Working from the bottom left in Fig. 5.8—where the north–south axis runs diagonally from top left to bottom right—the triangular shell to the south-west of the pivot point at the centre of the courtyard has two sides of around 36 m and one of about 24 m. To the north-west, there is another triangular shell with side lengths of approximately 37 m, 41 m and 41 m, respectively. The largest, north-eastfacing shell, of around 75 m  42 m overall, is the most sculptural. It faces the major thoroughfare Willy Brandt Allee where, if built, it would have formed an iconic image

to draw the attention of passing motorists to the museum. The folded form rises from five supports and covers the main entrance. One leg of the shell spans over the drop-off area for taxis and buses to provide some shelter from adverse weather. On the north- and east-facing edges of this shell, there are two curved arched forms of 24 m and 35 m span, respectively. These arches buttress a spectacular twisted, vaulted opening that rises to a height of over 20 m above the entrance. It is the most complicated shape of the four—“… there is no “euklidisch” [Euclidean] geometry behind it” (Balz 2018). Michael Balz recalls that his precedent and proof of concept for this particular shell was that which Heinz Isler had realized at the Sicli SA factory in Geneva, in 1969, which rises from seven bases and has no symmetry (Balz 2018). That shell is smaller, at 58 m  35 m overall but includes a similar vaulted opening. Finally, to the southeast a further triangular shell has a maximum span of approximately 49 m, with two shorter sides of about 32 m each. The external free edges are all curved in plan while edges between adjacent shells are straight but not parallel. It should be noted that some of these free-form shells have spans that are at the limit of the largest previously

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Fig. 5.6 Orchid flower inspiration for the tower form. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 5.7 Model of the final competition entry against a background of wooded landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 5.8 Model of proposed shell roofs for the German National Museum of Contemporary History, Bonn, arranged like petals of a flower around a central courtyard. The shadows reveal the curvature of

the forms. Reproduced from photograph by Michael Balz with permission from Michael Balz

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engineered by Heinz Isler. The maximum clear span of the Grötzingen shell (see Chap. 3) is 42 m and Isler’s standard tennis/sports hall shells, introduced in 1978, typically span 18.6 m  47 m but are rectangular on four supports: a later variation used for an air museum in Dübendorf, near Zürich, in 1987, extended to 51.7 m. Ultimately, Michael Balz has commented “…the planning between the shell and the function [of the enclosed space] is the most important thing which you have to find out…” (Balz 2018). The building perimeter was enclosed with fully glazed curtain walling, set back from the shell edge. Tapering glazed strips were proposed to link the concrete roofs and introduce natural light into the exhibition spaces. These were designed with a step between the height of adjacent shells so that they could be closed with flat glass panels using straight glazing profiles. When discussing this project in 2018, Michael Balz suggested that today the slots between the shells might have been closed with twisted glass precisely following the curved shell profiles (Balz 2018). Years later, in 2007–8, together with Werner Sobek, he incorporated such glass in the re-glazing of the ‘teardrop’ roof window of Frei Otto’s cable net-roofed IL tent, now the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart, during its renovation, see Fig. 1.3.

5.3.3 Internal Planning In the design of non-conventional structures such as shells and tensile membranes, additional care has to be taken with the internal planning. In more conventional rectilinear construction, it is relatively easy to appreciate the relationship between floors and (usually) vertical walls. However, when the roof is an organic double-curved surface, its free-form derived by physical experiment and with a geometry extremely difficult to define mathematically, it is important to ensure that, for instance, floors do not penetrate the roof surface and that there is adequate headroom over the full floor plate. With a double-curved roof, a physical model is indispensable for this purpose, to verify the required spatial arrangements which can then be transferred to conventional plans and sections as shown in Figs. 5.9 and 5.10. Mezzanine floors, shown shaded red in Fig. 5.9, are accessed by spiral stairs round large circular central columns. They are raised up into the volume created by the shells and stepped back to avoid conflict with the curved surfaces. A more extensive intermediate floor (shaded green) is supported by columns above ground and basement levels that extend to the full plan of the building envelope. Roof glazing between the shells and the inclined façade glazing of the entrance under the largest shell is shown shaded in blue and the full extent of the shell is shaded yellow. The three-dimensional

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relationship between the floors and the shell surfaces can be seen in the cut-away view of the model, Fig. 5.11.

5.3.4 Appreciation While discussing the design of this project with Michael Balz in June 2018, our conversation turned to the general process of architectural design of shells. It was revealing, given the vocations of his mother and grandfather, when he commented that “…the process of designing has to do with the fantasy [imagination] of the sculptor, who knows and must bring light in…in a way which can be realized by normal craftworkers” (Balz 2018). He evidently perceives concrete shells as large-scale sculptural forms exhibiting a complex interplay of structure and light, imagined by the architect but executed by skilled constructors. A further remark suggests that he considers that, to design with shells, the architect needs a certain level of experience, in order to be able to handle the complexities of designing with light and form: “… for young people, which never built anything, it is not easy to have the imagination to know if it is possible or not” (Balz 2018). The north-east elevation, shown in Fig. 5.10 (top), reveals how the height of the largest shell and extensive area of inclined curtain wall glazing accentuates the main entrance. It also discloses how the proposal sits within its context, without overshadowing or overpowering the surrounding existing conventional buildings. The rounded shells appear like small hills in the landscape. Regrettably, it is difficult to gain much insight into the architectural qualities and character of the interior spaces. From the rendered sections, Fig. 5.10, which were drawn by Michael Balz’s collaborator Johannes Fritz, and the cutaway view of a model shown in Fig. 5.11, where the shell over the entrance has been removed, it can be imagined that the linked shells will provide a very light and airy enclosure. But it is not possible to envisage the way that light (and sound) will reflect off the various curved surfaces, although there is some suggestion of how light from the façades and rooflight glazing might interact with the opaque double-curved concrete shells in the shading of the sections. However, a mixture of diffuse and direct light would enable the double curvature of the shell to be perceived more clearly. As Michael Balz has said “… [the play of light] belongs to the ‘skilfulness’ of the modelmaker, of the inventor of the shell […] but there is no law where it’s written [that] you have to do the glass like this” (Balz 2018). Figures 5.12 and 5.13 show front and rear views of the model displayed in the landscape, revealing the disposition of the mezzanine floors and demonstrating the powerful impact the shells would have made, if constructed.

Fig. 5.9 Plan of competition entry for proposed German National Museum of Contemporary History, Bonn showing relationship of shell roofs (boundaries shaded yellow) to mezzanine and intermediate floors (red and green, respectively). The roof glazing and inclined façade glazing are shaded blue. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.10 North-east elevation (top) and sections B–B (middle) and A–A (bottom) as shown in Fig. 5.9 of the competition entry for proposed German National Museum of Contemporary History, Bonn, show the relationship between the thin shells and the stepped floor plans. Reproduced from rendered drawing by Johannes Fritz with permission from Johannes Fritz

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Fig. 5.11 Cut-away view of model of the proposed German National Museum of Contemporary History, Bonn, with the shell over the main entrance removed. Reproduced from photograph by Michael Balz with permission from Michael Balz

At the time of the competition, the high-tech architecture style was well established—the competition-winning Centre George Pompidou, in Paris, by Richard Rogers and Renzo Piano, was completed a few years earlier in 1977—and concrete shells were perhaps perceived as passé or unfashionable. Michael Balz says that he and Johannes Fritz only entered the competition because they were aware that Günther Behnisch, who they believed would be well disposed to the incorporation of non-conventional structures such as free-form shells, had been confirmed as a member of the jury. They knew that Behnisch had collaborated with Heinz Isler and Jürgen Joedicke, when in 1967 they won the competition for the design of the Olympic Stadium in Munich, which incorporated a large cable net roof. They

believed that with Behnisch’s interaction with Isler twenty years earlier he would be well aware of the potential of thin reinforced concrete shells. Sadly, Michael Balz says that he considers that their entry was assessed by jurors with limited understanding of shell construction technology. The proposal was declared “not buildable” and was eliminated in the first round. This criticism and resulting rejection were clearly undeserved as the built precedents of the Naturtheater Grötzingen and Sicli SA factory in Geneva, which were of similar size, testify. The winning design by Ingeborg and Hartmut Rüdiger, of Rüdiger and Rüdiger, which opened in 2000 (ARCHITEKTENRÜDIGER 2022) is of more conventional ‘Bauhaus-style’ construction. The rectilinear building is topped

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Fig. 5.12 View from the north-east of the physical model of the proposed German National Museum of Contemporary History, Bonn, showing the largest (entrance) shell within the landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 5.13 View from the south-west of the physical model of the proposed German National Museum of Contemporary History, Bonn, showing how the shells group round the courtyard and within the

landscape. Reproduced from photograph by Michael Balz with permission from Michael Balz

by three glazed arched roofs that run parallel to Willy Brandt Allee. It should be noted that these roofs, originally with glazing incorporating built-in blinds, were reglazed in 2016– 17 using double screen-printed, triple-insulating glazing with a shading layer (Roschmann Group 2021). Both solutions

are what one would anticipate to be needed in order to mitigate against possible glare and overheating from the large areas of roof glazing. This might have been avoided if Michael Balz’s shell solution with more limited glazing had been selected.

5.5 German Pavilion, Expo’2000, Hanover (1997)

5.4

Badezentrum Sindelfingen (Thermal Baths), Böblingen (1983)

5.4.1 Introduction To the south-west of Stuttgart, the Mineraltherme thermal baths at Böblingen-Sindelfingen, home of Mercedes Benz, is one of the major spas of the region. Strongly mineralized water drawn from a depth of 775 m is attributed with healthgiving and medicinal properties (Mineraltherme Böblingen 2021). The competition to enclose several pools and related amenities provided the perfect opportunity for Michael Balz to apply his architectural skill to the design of a more audacious pool shell roof than those already proven by Heinz Isler with architects Haus und Herd, for example, the 35 m  34 m rectangular plan of the swimming pool roof, in Brugg, Switzerland, in 1981 (Chilton 2000; Ramm and Schunk 2002).

5.4.2 Thermal Baths As can be seen in the site plan, Fig. 5.14, the thermal baths consist of a number of separate indoor and outdoor pools of disparate shape and size, which contain water at different temperatures. Alongside these is a requirement for changing rooms, sauna and massage rooms, café, and ancillary facilities, which are housed below landscaped terraces. The arrangement of the pools on a gently sloping site encourages the use of a free-form for the roof in order to embrace all under one contiguous canopy.

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to illuminate the entrance, Figs. 5.16 and 5.17. Opening to the south-west, the fully glazed façade increases solar gain in winter. In addition, the curved form of the shell reduces the internal volume that needs to be heated in winter or cooled in summer.

5.5

German Pavilion, Expo’2000, Hanover (1997)

5.5.1 Introduction A World Fair or Exposition (Expo’) is an occasion for nations to present a forward-looking image of their country for a large international audience. The theme for the Hanover Expo’—“Mensch, Natur und Technik—Eine neue Welt entsteht” (Man, Nature and Technology—A New World Emerges)—was perhaps more wide ranging than that of other expositions. Pavilions focused on presenting solutions for future living rather than acting directly as a showcase for technological advances. As host nation, the German pavilion was located in a prominent position on the main Expo-Plaza, see Fig. 5.18. In consideration of this, one might think that to propose a building incorporating thin reinforced concrete shells— technology that was at its zenith between the 1950s and 1970s, in Europe at least—would be counterintuitive. Yet with advances in concrete technology and methods of forming double-curved surfaces, as well as the increasing interest in sustainable forms of construction—shells being highly efficient structures requiring minimal material to achieve substantial spans—such a suggestion was not as incongruous as it might initially seem.

5.4.3 Shell Roof The proposed shell form roof, Fig. 5.15, derived using a hanging membrane is one of the most complex proposed by Michael Balz. As with previous hanging models, each free edge is stiffened by an upturned lip, which emerges naturally during the form-finding process. The single shell, symmetrical about a roughly north-east to south-west axis, comprises a larger surface of approximately 60  70 m overall, which rises from eight individual bases. Similar to the proposal for the museum in Bonn, two simple arched profiles frame a large dramatic penetration, which extends to almost the centre of the shell. To the north, a smaller triangular surface, with side lengths of 20–25 m and one additional base, merges with the larger surface at two of its bases and shelters the main entrance. There is a lenticular glazed strip between the two sections of the shell

5.5.2 Proposed Pavilion Michael Balz’s proposal for the German pavilion, at Expo’2000, in Hanover, addressed the theme by presenting an organic-formed building as a symbol of the need for increased symbiosis of humanity with nature in the twentyfirst century. It incorporated naturally shaped shells, born through experiment and created under the natural influence of gravity acting on flexible hanging membranes. This Michael believed would serve as an encompassing germinal structure for future organic technological developments, Fig. 5.19, and a symbol for society’s closer integration with nature in the next century. The pavilion was roofed with a symmetrical arrangement of two organic free-form reinforced concrete shells, shown

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Fig. 5.14 Site plan for the proposed thermal baths at Sindelfingen, Böblingen. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.15 View of model with the roof shell form-found by hanging membrane. Reproduced from photograph by Michael Balz with permission from Michael Balz

in section in Fig. 5.20. These have a maximum span of approximately 90 m and rise from 18 m at the outer lip to 33 m at the summit. They are separated by a glazed atrium of around 25 m at its widest. In the longitudinal direction, the glazed building envelope, which follows the shell plan profile inward from its edge, stretches over 100 m and around 130 m to the extremities of the shell buttresses.

The form of the shells appears to be somewhat similar to that used for the Naturtheater, Grötzingen, in 1977–78 (see Sect. 3.3) but in this case on four bases rather than five. It is also proposed to build the shells at a much larger scale— approximately double the span and three times the rise. During the form-finding process scale is not relevant—a funicular form will work in precisely the same way at any

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Fig. 5.16 View of model with the roof shell form-found by hanging membrane. The lenticular glazed opening can be seen between the larger shell surface and the triangular shell over the main entrance. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 5.17 View of model from east showing the surrounding terraced roof, the merged shell base and lenticular rooflight to the right. Reproduced from photograph by Michael Balz with permission from Michael Balz

scale. However, the practicalities of design and construction are not the same. Realization of the shells would have been a considerable, but not insurmountable, engineering challenge—for example, the triangular-plan shell roof of the Centre des Nouvelles Industries et Technologies (CNIT) constructed in Paris from 1956 to 1958, engineered by Nicolas Esquillan (1902–1989) has maximum spans of over 200 m. Unlike in Grötzingen, here the site is not sloping. Consequently, each shell springs from bases at the same level and is inclined away from the central atrium, which opens out towards the pavilion main entrance facing the ExpoPlaza, Fig. 5.18. The atrium glazing is suspended in a catenary between the two shells.

A centrally located main presentation theatre extends from the basement through ground and first floors with access at all levels, Fig. 5.22a–c. In the basement, this is accompanied by car parking, cloakroom, kitchens, service and technical facilities. The ground level accommodates the main entrance from the Expo-Plaza, with information desk and souvenir shop, restaurant, event rooms and additional service zones. At first floor, there are exhibition spaces, external stages, administration offices and press facilities. The second and third floors have further exhibition, administration and press facilities, terminating at the highest level with a mezzanine VIP lounge 18 m above the ground, which takes advantage of the pavilion’s elevated position to offer views over the Expo-Plaza, Fig. 5.22d-f.

5.5.3 Internal Planning 5.5.4 Aesthetic Considerations As in the proposal for the museum in Bonn, the internal planning is required to adapt to the curved form of the shells, Fig. 5.21. Accommodation is distributed over six floors (including basement) with the organically formed floor plates stepping back as required by the profile of the shell surface.

In comparison with this proposal for a striking pair of organic free-form shells, the winning design by architects Wund Gruppe, with structural engineers for the roof Arcadis Deutschland GmbH, was a more conventional rectilinear building of 103.5  141 m, which almost completely filled

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Fig. 5.18 Location plan showing Michael Balz’s proposal for the German Pavilion, at Expo’2000, in Hanover, overlooking the Expo-Plaza. Reproduced from drawing by Michael Balz with permission from Michael Balz

5.6 Hegau Auto Rast: Motorway Service Area, Near Engen (1997)

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Fig. 5.19 Model of the proposal for the German Pavilion, at Expo’2000, in Hanover, with shell forms derived using hanging membranes. Reproduced from photograph by Michael Balz with permission from Michael Balz

the site. The main innovative aspect of the design was its curved glazed façade and steel columns stabilized by cables and glass plates.

5.6

Hegau Auto Rast: Motorway Service Area, Near Engen (1997)

5.6.1 Introduction Motorway service areas are often dull and dismal purely functional places, somewhere to quickly take a comfort break or to consume a snack or drink a coffee. Most make little attempt to provide a truly relaxing and calming environment to refresh travellers before they continue on their journey.

5.6.2 Competition Entry In his design competition entry for a motorway rest and service area, which was to include a 400-seat restaurant and shopping area, Michael Balz attempted to address this deficiency. For the enterprise located on the Bundesautobahn 81, near the town of Engen in the Hegau region of Federal State

Baden-Württemberg in southern Germany, he abandoned more traditional building forms and proposed a grouping of 6–7-m span shells of more natural outline to engender a soothing and welcoming atmosphere. Perhaps recalling the impact of Heinz Isler’s inclined triangular shells for the motorway service station at Deitingen Süd, constructed in 1968, his competition entry also included a prominent inclined shell, Fig. 5.23, to signal the rest stop and service station to passing motorists. In this case, the predominant shell was rectangular in plan and set at the centre of a semicircle of the tapering vaults, Fig. 5.24. Markus Balz, who was assisting his father at the time, recalls meetings at a picturesque watermill, a hotel owned by the client about 10 km from the site. One meeting was also attended by Heinz Bösiger, in order to reassure the client about the buildability of the shells (Balz 2020). A major complication was that the competition was restricted to architects from the Black Forest–Lake Constance locality and, therefore, theoretically not open to Michael Balz. However, he reached an accommodation with a friend and local architect, Siegfried Ruge, from Villingen-Schwenningen. He had previous experience of free-forms, having earlier proposed a shell roof for a swimming pool and was, therefore, amenable to Michael Balz’s design being entered under his name.

Fig. 5.20 Cross-section north/south (top) and long-section west/east (bottom) of the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 5.21 Model showing the organically formed floors of the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from photograph by Michael Balz with permission from Michael Balz

Unfortunately, despite the restaurant proprietor being aware of Michael Balz’s skill with shell design and him having reacted very positively to sketches he had seen prior to the formal entry, the proposal was summarily rejected in the first round. The chair of the judging panel was adamant that there was no place in the landscape for shell structures and that there must be what he referred to as ‘Swabian’ shapes that blended with local vernacular architecture—a purely subjective view. Michael Balz remarks that, since then, “…at the other side of the autobahn they built a thing which looks like a sausage!” (Balz 2018). To insulate motorists from the noise and speed of the motorway as much as possible, the shells are lower to the north-east where they face the passing traffic and parking areas, Fig. 5.25a. However, they open up in height and width towards the south-west where they benefit from afternoon sun and offer views over a terrace and the surrounding countryside, Fig. 5.25b, c. The form of the shells captures and reflects natural daylight deep into the building.

5.7

Epilogue

The competition entries described in this chapter have spanned a period of more than 30 years, from what was perhaps the highpoint of reinforced concrete shell construction in the late 1960s to the start of the new millennium in 2000. They have shown the capacity of free-form shells to create exciting organically shaped enclosures for a diverse range of architectural spaces at a widely different scale. Unfortunately, none have been successful. They have been rejected, apparently, for a number of different reasons. The pneumatic forms for the Evangelical Lutheran church, in Heilbronn, were perceived as ‘too Islamic’; the spectacular spans for the Haus der Geschichte, in Bonn, were considered to be ‘not buildable’, despite evidence to the contrary provided by significant precedents; and the Hegau Auto Rast was condemned outright by the chair of the jury because they considered that it did not blend appropriately with the

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a

b

C

Fig. 5.22 a Basement (top); b ground/entrance (middle); c first (bottom); d second (top); e third (middle); and f mezzanine (bottom) floor plans for the proposal for the German Pavilion, at Expo’2000, in Hanover. Reproduced from drawings by Michael Balz with permission from Michael Balz

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d

e

f

Fig. 5.22 (continued)

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Fig. 5.23 Model for the proposed Hegau Auto Rast, with inclined central shell. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 5.24 Plan view of model for the proposed Hegau Auto Rast. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 5.25 a North-east (top); b south-west (middle); and c north-west (bottom) elevations of the Hegau Auto Rast shells. Reproduced from drawings by Michael Balz with permission from Michael Balz

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vernacular architecture of the locality. Yet there was also, almost certainly, an underlying prejudice against the construction of reinforced concrete shells in Europe during this period. Steel-framed, glass-clad construction was on the ascendancy from the late 1960s, as it was perceived to be lighter in weight and also admitted more natural light to the building. On the other hand, the popularity of concrete shells began to decline as they were perceived to be heavier, both in weight and visually, more difficult and expensive to construct due to the need for curved formwork—although this was not necessarily true—while not providing the same transparency as the steel-framed alternatives. Notable exceptions were the shells of Heinz Isler, where his output only began to decline in the 1990s, and those constructed by Ulrich Müther in East Germany—the former German Democratic Republic (GDR)—where steel was in short supply and labour costs were much lower (Lämmler and Wagner 2010; Beckh et al. 2020).

References ARCHITEKTENRÜDIGER (2022) Haus der Geschichte der Bundesrepublik Deutschland. Available https://www.architektenrue diger.de/www.architektenruediger.de/12_Architekten_Rudiger_HD G.html. Accessed 12 Aug 2022 Balz M (2018) Recorded conversation with John Chilton at the Balz House, Stetten auf den Fildern, 5 June 2018

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Balz M (2020) Recorded online conversation with John Chilton, 13 Nov 2020 Beckh M, Del Cueto Ruiz-Funes JI, Ludwig M, Schätzke A, Schützeichel R (eds) (2020) Candela Isler Müther: positions on shell construction. Birkhäuser Verlag, Basel Chilton JC (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford Ltd., London Chilton J (2009) 39 etc...: Heinz Isler’s infinite spectrum of new shapes for shells. In: Lázaro C, Domingo A (eds) Evolution and trends in design, analysis and construction of shell and spatial structures. Proceedings of the international association for shell and spatial structures (IASS) symposium 2009. Editorial de la UPV (Universidad Politécnica de Valencia), Valencia, pp 51–62. Available http://hdl.handle.net/10251/6465. Accessed 13 Nov 2020 Faber C (1963) Candela: the shell builder. Reinhold, New York and London Fritz J (2021) Personal communication, 22 Sept 2021 Isler H (1961) New shapes for shells. Bull Int Assoc Shell Struct 8: [Paper C-3] Kohl H (1982) Deutscher Bundestag—9. Wahlperiode—121. Sitzung. Bonn, 13 Oct 1982, 7227. Available https://dserver.bundestag.de/ btp/09/09121.pdf. Accessed 12 Aug 2022 Lämmler R, Wagner M (2010) Ulrich Müther shell structures. Verlag Niggli AG, Zurich Mineraltherme Böblingen (2021) Das Thermalwasser der Mineraltherme [The thermal water of the Mineraltherme] (in German). Available https://www.mineraltherme-boeblingen.de/start/Thermal bad/Unser+Thermalwasser.html. Accessed 4 Mar 2021 Ramm E, Schunk E (2002) Heinz Isler Schalen: Katalog zur Ausstellung. Hochschulverlag AG an der ETH Zürich Roschmann Group (2021) Haus der Geschichte der Bundesrepublik Deutschland. Available https://roschmann.group/en/projects/hausder-geschichte/. Accessed 14 Jan 2021

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Abstract

Selected unrealized projects by Michael Balz, mostly in collaboration with Heinz Isler as advisor for construction and engineering, are described and related to development of the built shells and competition entries. Projects include proposals for a leisure pool roof at the Tropicana, Lucerne (1979), an atelier and office building for Willi Bösiger AG Langenthal, Switzerland (1986) and Shell of Peace, at the Heliopolis University, Cairo, Egypt (2016).

6.1

Introduction

In parallel with the shells he has designed for competitions, Michael Balz has planned a number of, sadly unrealized, shell projects, mostly developed in collaboration with Heinz Isler as advisor for construction and engineering. Two unrealized shell designs, a house for a private client and a dwelling for Heinz Isler and his wife Maria, have already been introduced in Chap. 2. They were developed as a natural progression from the living shells that the collaborators were developing at the time. Proposals of larger scale and complexity followed the successful completion of the Theater unter Kuppeln, Stetten (1976), Naturtheater, Grötzingen, Aichtal 1977–78) and Ballettsaal (Ballet Salon), Stetten (1979), described in Chap. 3. As I have suggested previously (Chilton 2010), one of the possible reasons that relatively few free-form shells were engineered by Heinz Isler was because such shells are often the most striking element of the building envelope—the petrol station roofs at Deitingen Süd (1968) and the Sicli SA factory in Geneva (1969) for example (Chilton 2000). These present a very distinct and dominant architectural statement, which conventionally one would normally expect to be conceived by the architect not the engineer. However, David Billington, when commenting on the Sicli shell, has suggested that “…the inherent potential for thin-shell concrete © Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_6

roofs … can happen only if the architect or owner gives the structural artist full control of making the form”. In that case, Isler was asked to design the shell and the architect, Constantin Hilberer (1923–1988), concurred (Billington 2003: 143). Accordingly, it is possible that many architects were hesitant to work with him because they preferred to retain control of the external form of their building envelope. For an efficient shell structure, it is best if the geometry is close to the funicular surface, where there is minimal (or no) bending and forces are primarily in the plane of the surface, when the shell is loaded by its own weight. This surface geometry is usually derived by a form-finding process controlled by the engineer rather than the architect—in the case of Heinz Isler, the process was by inversion of the shape of freely hanging membrane models. This process can limit the input from the architect unless there is a close collaboration and synergy between the two disciplines. The creative rapport between Michael Balz and Heinz Isler was such a connection, reinforced by the architect’s own experimentation with inflated membranes and hanging membrane models for preliminary design, which resulted in a special mutual understanding.

6.2

Tropicana, Lucerne (1979)

The first large-scale unrealized project was for a leisure pool complex in Lucerne, in 1979. This was in the same year as the second shell in Stetten, the Ballettsaal, was completed. Three alternative preliminary proposals are shown in sketch form in Fig. 6.1, with minor and major axis elevations, and roof plans. The proposal to the left of Fig. 6.1 shows a single continuous shell surface on six separate bases. It is approximately oval in plan, symmetrical about both primary axes and has a very large lenticular glazed rooflight piercing the shell along the minor axis. In the centre of Fig. 6.1, a second proposal has two separate shells that overlap slightly. That to the left is larger and higher. Both are symmetrical 135

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Fig. 6.1 Alternative sketch proposals of shell roofs for the Tropicana, Lucerne. Reproduced from drawing by Michael Balz with permission from Michael Balz

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6.3 Atelier and Office Building for Willi Bösiger AG Langenthal, Switzerland (1986)

about a common central axis. Again, there is a large rooflight linking the two shells, in this case with inclined glazing due to the difference in height of the leading shell edges. The glazing also extends down to ground level between the shells. There are four individual bases and, where the two shells overlap, potentially, two larger shared bases. To the right of Fig. 6.1, a single shell of roughly square plan on four supports forms one continuous surface with a large ‘teardrop’-shaped glazed opening in one quadrant along one diagonal axis. The elevations reveal how the shell edge is curved to form a stiffening upturned lip around the rooflight. However, the first two of these were not developed in more detail. The proposal shown to the right in Fig. 6.1 was further developed in the scheme shown in Fig. 6.2, a drawing dated 19th June 1979. This reveals an irregular pentagonal building plan of approximately 32 m maximum span, covered with a single shell on five supports, on a site that slopes gently to the south. The shell roof is symmetrical about the primary axis of the large, ‘teardrop’-shaped glazed rooflight—perhaps an echo of the rooflight in the cable net roof of the IL in Stuttgart. It inclines towards the south and provides ample natural daylight to the leisure pool and terraces within the envelope. The shell contours create a protective and airy interior while minimizing the volume of the enclosure, which has vertical fully glazed façades on a straight-sided pentagonal plan, inset from the perimeter of the shell. This arrangement demonstrates Michael Balz’s concern for the environment at a time when this was still in its relative infancy. The low surface area of the shell minimizes material used in the building envelope and reduces heat losses from it. Similarly, the lower internal volume reduces winter heating and summer cooling energy requirements, and the rooflight reduces the demand for artificial lighting.

6.3

Atelier and Office Building for Willi Bösiger AG Langenthal, Switzerland (1986)

This is perhaps the most extensively developed of the unbuilt projects. Willi Bösiger AG was the contractor for the majority of reinforced concrete shells engineered by Heinz Isler for around 50 years. Therefore, it is not surprising that when seeking an architect to design a new atelier and office building at their facility in Langenthal, Switzerland, they turned to long-term Isler collaborator Michael Balz, who had recently successfully completed innovative shell constructions with him in Stetten and Grötzingen. The Langenthal site already had eight of Isler’s standard industrial 20 m

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20 m ‘bubble’ shells so the brief was to design a distinctive iconic building for the company to publicize their expertise in free-form shell construction. Michael Balz carried out the initial form-finding using a hanging fabric membrane using the apparatus shown in Fig. 6.3, from which he produced a concept model Fig. 6.4. A wireframe model based on this was made by Heinz Isler to indicate the approximate profile for the shell springing from six bases, as shown placed over the proposed basement plan in Fig. 6.5. Using this rough wire outline as a guide, he made an exploratory model using plaster on suspended woven fabric, Fig. 6.6. Subsequently, a base board was fabricated, Fig. 6.7, to suit the proposed roof plan and in order to produce possible alternative more precise shell geometries using a hanging latex membrane. It should be noted that with this technique there is not just one solution but a continuum of alternative solutions depending on a number of variable parameters during the form-finding process. The baseboard reveals some clues as to the technique. The anticipated shell perimeter form is drawn on the baseboard (the outline depicted by a dashed line) within a varnished, irregular, hexagonal zone having one axis of symmetry. This is bounded by thin wooden strips. There are also more substantial wooden blocks at the six predetermined shell base locations, positioned perpendicular to the expected direction of the reaction forces at each support—probably determined using the exploratory model. These blocks were used to clamp in place an elastic membrane (usually a high-quality latex rubber sheet) that had been trimmed approximately to the shape of the irregular hexagonal area between the blocks. Small pieces of latex sheet (brown) can still be seen attached to the blocks. A thin layer of gypsum-based plaster was then applied at a constant depth controlled by the thickness of the thin wooden strips on the perimeter. Once this had been applied, the hexagonal section of the baseboard, which is actually a separate cut-out, can be gently dropped to allow the membrane to take up its funicular hanging form due to the weight of the plaster under the action of gravity. The split base, hinged as seen on the left of Fig. 6.7, facilitates this and can also be used to apply an initial prestress to the membrane. Once the plaster has set, the cast can be inverted to become a compression shell under its own weight. Examples of two of the precisely modelled plaster casts are shown in Fig. 6.8a–b. Both have lines projecting the direction of thrust from the bases across the shell surface. The model shown in Fig. 6.8a (top) also has markings for accurate measurement of the surface geometry which would be scaled up to define the final shell profile.

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Fig. 6.2 Detailed sketch proposal for shell roof for the Tropicana, Lucerne. Reproduced from drawing by Michael Balz with permission from Michael Balz

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6.3 Atelier and Office Building for Willi Bösiger AG Langenthal, Switzerland (1986)

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Fig. 6.3 Initial form-finding hanging fabric membrane model by Michael Balz, of the proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 6.4 Concept model of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Photograph John Chilton with permission from Michael Balz

I encountered the wireframe, exploratory model, baseboard and precise plaster casts in Heinz Isler’s studio in Lyssachschachen, shortly before his bequest was transferred to the Heinz Isler Archive at the Institute for the History and Theory of Architecture (gta) and the Chair of Structural Design at the Swiss Federal Institute of Technology (ETH) in Zurich in 2011. There were several iterations of the project over a number of years. The proposed ground floor plan, version dated 4th

April 1986, Fig. 6.9, shows the relationship of the shell surface—the dashed boundary—to the enclosed building and the support locations. With maximum clear spans of 31.00 m by 47.00 m, the shell is symmetrical for ease and economy of construction, although earlier proposals were not. The shell was initially designed to spring from ground level. However, in a later section, Fig. 6.10, dated 9th July 1989, it can be seen that the shell was subsequently raised

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Fig. 6.5 Initial wireframe model for Willi Bösiger AG studio and office building encountered in Heinz Isler’s studio in 2011. Photograph John Chilton with permission from the Isler family

6.4 Wallwitzhafen Dessau: Freizeit Park (Leisure Park) (1992–93)

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Fig. 6.6 Heinz Isler’s exploratory model form-found with suspended woven fabric for Willi Bösiger AG studio and office building. Photograph John Chilton with permission from the Isler family

above ground level in order to provide more office space, just as the shell of the Balz House is raised to provide more accommodation. The shell rises to approximately 10 m above the principal floor level at its highest point. There are two basement levels protected by earth banking and an upper mezzanine floor that steps back following the inclined profile of the shell, with views over the entrance atrium. To highlight the slenderness of the shell, the vertical façade glazing is set back from the shell edge around the full perimeter. On the west elevation, it is penetrated by a balcony accessed from the mezzanine. Elevations in Fig. 6.11 reveal the context of the proposed atelier and office building in relation to the existing on-site Isler ‘bubble’ shell workshops and stores. The elevation ‘Ansicht West Gaswerkestrasse’ shows the dramatic view that would have confronted visitors on arriving at the Bösiger AG site, if the shell had been constructed. In an earlier alternative, in March 1989, a terrace raised on columns similar in form to those used in the café at Stetten (see Figs. 3.37 and Figs. 3.38) was proposed in place of the earth banking.

Given the exciting proposed shell form, it is somewhat disappointing that the atelier and office proposal was never realized. Unfortunately, because of other commitments at the time, Willi Bösiger AG did not have the time or resources to devote to this more complicated and unusual building. Eventually, in 1998, a standard Isler 25 m  25 m ‘bubble’ shell was built to house the facilities and functions that had been intended for this shell. The premises are currently occupied by the construction company HE Hector Egger Bauunternehmung AG.

6.4

Wallwitzhafen Dessau: Freizeit Park (Leisure Park) (1992–93)

The city of Dessau is located in the former German Democratic Republic (GDR), on the River Elbe. It is renowned among artists and designers as the location of the Bauhaus building designed by the architect Walter Gropius (1883–1969). Following the reunification of Germany, in 1990, there was a widespread feeling of optimism supported

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Fig. 6.7 Baseboard used to create the precise hanging form-finding shell models for Willi Bösiger AG studio and office building. The hexagonal zone, bounded by the thin wooden strips, can be released

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Unrealized Shell Projects

and dropped after a plaster-covered latex membrane has been stretched between the large wooden blocks. Photograph John Chilton with permission from the Isler family

6.4 Wallwitzhafen Dessau: Freizeit Park (Leisure Park) (1992–93)

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Fig. 6.8 Precise plaster models produced by Heinz Isler’s hanging membrane method for Willi Bösiger AG studio and office building a showing locations of profile measurement points (circled); and b plan

view with thrust lines from the bases projected across the surface. Photographs John Chilton with permission from the Isler family

by massive state investment into the former East Germany in an attempt to redress wide social and economic differences between the two previously separate states. This Freizeit Park (Leisure Park) project was initiated by a developer who was intending to reclaim a site adjacent to the former Bahnhof Dessau Wallwitzhafen railway station and the River Elbe, just downstream of its confluence with the River Mulde. Wallwitzhafen had previously been a small industrial port and the site was occupied by railway sidings

until 1972 (Wichmann and Wichmann 2022). At the time the leisure park was projected (in 1992–93), the River Mulde was heavily polluted by effluent from chemical plants upstream in Bitterfeld and there were substantial funds available for projects to improve the river. The proposal followed three years after the successful completion of the final Musical-Saal (Music Salon) shell at Stetten. With his experience of the various Stetten shells’ construction and given the different functional requirements

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Fig. 6.9 Ground floor plan dated, 4th April 1986, of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.10 Section of proposed atelier and office building, dated 9th July 1989, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.11 West (top) and south (bottom) elevations, dated 9th July 1989, of proposed atelier and office building, for Willi Bösiger AG Langenthal, Switzerland. Reproduced from drawing by Michael Balz with permission from Michael Balz

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6.5 Thane, Near Mumbai, India: Modular Dwelling Units (1994) and Cosmo Ville, Amenities Centre (1995)

of the buildings proposed in the development, Michael Balz was presented with an opportunity to give full rein to his passion for organic architectural shell forms arranged in a landscaped location. The complex included an ice/roller skating rink, indoor and outdoor swimming pools, indoor tennis courts, conference centre/hotel, viewing tower and beer garden, Fig. 6.12. It also included a proposal to reinstate the earlier passenger station on the neighbouring Roßlau (Elbe)–Dessau railway line. This proposal had shell-formed platform canopies to match, seen in plan, top right, in Fig. 6.12. It was proposed to cover the ice rink by two opposing shells, each similar in form to that constructed at Grötzingen (see Sect. 3.3), with a large lenticular rooflight between to introduce natural daylight—similar to one of the alternatives proposed for the Tropicana, Lucerne (see Fig. 6.1). To cover the swimming pools, a shell reminiscent of the form proposed in the competition entry for the thermal baths at Sindelfingen, Böblingen, was indicated—see Sect. 5.4. Three of Heinz Isler’s well-proven sports/tennis hall shells were proposed to enclose the indoor tennis courts. The hotel had a tower over a central lobby linked to shellcovered meeting rooms, Fig. 6.13. The panoramic view of Fig. 6.14 shows a variation with a conference centre in place of the ice rink. All shells are form-found using the inverted membrane principle. Alas, in the end, the project did not receive funding and did not proceed. The site remains undeveloped and is currently just scrubland used for country walks.

6.5

Thane, Near Mumbai, India: Modular Dwelling Units (1994) and Cosmo Ville, Amenities Centre (1995)

Impressed by Michael Balz’s presentation at an international symposium on the Innovative World of Concrete, held in Bangalore from 30th August to 3rd September 1993, which was reported in an article in the magazine Indian Architect & Builder (Balz 1993), a senior manager of Soham Builders, from Mumbai, invited him to submit proposals for two (disappointingly unbuilt) developments at Thane, a Mumbai suburb. The first, in 1994, was for a system of modular dwellings. This was followed, in 1995, by designs for a meditation centre.

6.5.1 Flower House, Modular Dwelling The two-storey Flower House, Fig. 6.15, was conceived as a prefabricated system for shell dwellings. In some respects, this could be seen as a merging of the

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philosophies underlying the living environment of the Balz House (see Chap. 4) with a shell form similar to that constructed at the Europa-Park, in Rust, in 1994 (see Sect. 3.6), and ideas about prefabrication from the car ports developed with Willi Bösiger AG (see Sect. 3.7). Designed for mass production in reinforced concrete, to simplify construction and reduce the cost, the form of the shells is repeated symmetrically about two perpendicular axes. Two alternative planned layouts were proposed. The layout of Flower House 1, shown in plan in Fig. 2.18, has a floor area of almost 400 m2, excluding balconies, with the cantilevering shells extending 12 m from the centre of the core. Flower House 2, Fig. 6.16, is even bigger. Given their size and, therefore, construction cost, it can be reasonably assumed that they were destined for the luxury housing market in India. The dome-covered central core of the smaller Flower House 1 has a spiral stair to access the first floor from the entrance lobby. However, the larger Flower House 2 has a planted green space and small pool at the core to moderate the internal environment. This is open at the roof. Façades are mainly glazed but the overhanging shells provide shade to reduce solar gain. As in the Balz House, in both layouts most bedrooms are located on the ground floor, where it can be expected to be cooler, making it easier to sleep. Each opens onto a terrace shaded by a balcony which cantilevers from the first floor. The en-suite master bedrooms are on the first floor on the cooler north or east side of the house. Main accommodation—kitchen, dining and living room—is also on the first floor with, in Flower House 2, an open verandah that should experience cooling cross breezes as warm air is drawn through and exits via the roof oculus. The scheme did not go ahead as the developer ultimately failed to purchase the intended site.

6.5.2 Cosmo Ville, Thane, India (1995) In 1995, the overall site planning and a sketch design were undertaken for a luxury and organic, meditation and relaxation, development, Fig. 6.17, known as Cosmo Ville, also in Thane, India. The complex included an extensive estate of luxury housing, a mix of Flower Houses (types 1 and 2) and dwellings based on the ‘bio-segment’ system proposed by Michael Balz in 1971, Fig. 6.18, with accommodation arranged around a central courtyard. Crowning the highest point on the site a dramatic shell form was proposed as a temple for quiet meditation, Fig. 6.19. As the visiting German architect on the project, Michael Balz recollects that, in a highly crowded office of the city planning

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Fig. 6.12 Site plan of the proposal for a leisure park development in Wallwitzhafen, Dessau. From left to right: ice/roller skating rink; beer garden; indoor and outdoor swimming pools; hotel; viewing tower; and indoor tennis courts. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.13 Sketch of the proposed conference centre and Elbhotel at the leisure park development in Wallwitzhafen, Dessau. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.14 Panoramic sketch of an alternative scheme for a leisure park development in Wallwitzhafen, Dessau, showing diversity of proposed shells. Reproduced from drawing by Buro Isler with permission from the Isler family

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Fig. 6.15 Sketch of the proposed Flower House 1, Thane, near Mumbai, India. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.16 Floor plan and section of the proposed modular prefabricated Flower House 2, Thane, India, dated 12th December 1994. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.17 Site layout plan of Cosmo Ville development, Thane, India, dated 12th March 1994. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.18 ‘Bio-segment’ housing proposed for Cosmo Ville, Thane, India. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.19 Proposed meditation temple, dedicated to the Hindu god Surya, for Cosmo Ville development, Thane, India, dated 8th January 1995. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.20 Site plan and elevation of the Cosmo Ville, amenities centre, Thane, India—composed of four free-form shells around a lake. Reproduced from drawing by Michael Balz with permission from Michael Balz

6.6 Heliopolis University, Shell of Peace, Cairo, Egypt (2016)

authority, he was introduced to the official dealing with the application to develop the site. Noting the incorporation of the temple in the scheme, the official got chatting about the different gods worshipped in the Hindu religion and revealed that he was a devotee of one particular deity, Surya, the Hindu god of the Sun. Michael Balz remembers that in order to increase the overall chances of approval of the project the scheme’s temple was dedicated accordingly! The projected amenities centre featured four large free-form shells which were designed to cover a health club, shopping, restaurants and services, arranged around a small lake, for swimming. The elevation at the bottom of Fig. 6.20 shows the relationship of the individual amenity centre shells and the meditation temple located on higher ground. On this project, Michael Balz was generally liaising with middle managers and designers of Soham Builders. They were extremely surprised when he, a ‘lowly’ architect, was invited for dinner at the house of one of the company directors. Michael puts this down to being German, as, apparently, such an invitation would normally be unheard of.

6.6

Heliopolis University, Shell of Peace, Cairo, Egypt (2016)

The SEKEM Initiative was established in 1977 by Dr Ibrahim Abouleish (1937–2017) to realize his vision of holistic sustainable human development (Abouleish 2005; Abouleish 2016) which promotes social and cultural development through a blend of Islam and anthroposophy. At the inception, at a site sixty kilometres to the north-east of the centre of Cairo, he applied bio-dynamic (organic) agricultural methods to regenerate 70 ha of the barren desert. From these small beginnings, SEKEM has grown to be an important, socially responsible business, which is recognized worldwide (SEKEM 2020b). In line with their goal of education for freedom, in 2009 the Heliopolis University for Sustainable Development (SEKEM 2020a) was inaugurated under the auspices of SEKEM. The university was so named after the Ancient Egyptian city of Heliopolis, which was a major religious centre connected with the sun god Ra-Atum and located in what is now the northern suburb of Ain Shams in Cairo a few kilometres from the university. The name SEKEM derives from Ancient Egyptian and signifies ‘vitality from the sun’ (Seelos and Mair 2011). As Michael Balz has remarked (Balz 2018), Ibrahim Abouleish, the founder of SEKEM, had studied the writings of Johann Wolfgang von Goethe (1749–1832) and Rudolf Steiner (1861–1925) and was an advocate of anthroposophy, a philosophy that aligned closely with his vision. As a consequence, he was open to Michael Balz’s organic architectural forms—Michael is often asked if his architecture is anthroposophic, but asserts that, although it might be

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perceived as being related, it is not based directly on that philosophy. Ibrahim Abouleish was interested in realizing an ecologically based—what Michael Balz describes as an “Eco-centre” (Balz 2018) or eco-human—connection between the three principal monotheistic religions, Christianity, Islam and Judaism. The resulting proposal for the Shell of Peace, at Heliopolis University, Fig. 6.21, is an ongoing project for a building to be shared by Jewish, Christian and Islamic religions with a view to encouraging adherents of the three religions to come together. As Michael Balz declares, “…it is not a church, it is not a mosque, and it is not a synagogue; it is a neutral kind of theatre and it is to meet, to inform about different possibilities of religious thinking. It should be possible to present those three religions, not together but alone, like a theatre, like a musical”. He continues “… then they are forced not to be against but they are forced to think about their parallel ideas” (Balz 2018). When asked whether it is possible to emphasize the similarities and challenge the differences between the three religions through the medium of architecture, something that I suggested he appears to be trying to do, he replies “No. What I think we are speaking about [is] organic architecture—why not have a connection to those anthroposophic and also to religious visions?” (Balz 2018). With a plan inspired by hands crossed symbolically in a gesture of peace—represented by the fingers and thumbs of the two open-spread hands, Fig. 6.22—the Shell of Peace is conceived as two separate free-forms. One is a fully enclosed and air-conditioned conference hall for 750 people: this is nested with a larger open shell, designed to create an open-air forum space to seat 740, around a central stage area of approximately 350 m2. The shells are orientated along a roughly north–south axis, Fig. 6.23. Each free-form shell springs from five tapering supports (emulating the fingers and thumb of the crossed hands) and has a circular glazed rooflight. A vertical glazed façade closes the opening between the overlapped shells. Although both are free-forms, the curvature of the interlocking shells is designed to be parallel so that a consistent depth is maintained for the intermediate glazing. The intersection or overlap of the two shells symbolizes the coming together in peace and harmony of the three religions while the symmetrical layout of the buildings has an ordering effect on the architecture. Nature flows visually under the shells; orientation is simple and succinct. As can be noted in the elevations and sections, Figs. 6.24 and 6.26, the building is partially sunken into the site. The raked seating of the auditorium and forum, and their supplementary facilities, is all accommodated below ground level. This is beneficial in the climate of Cairo. The plan of the basement level, Fig. 6.25, shows how the theatre workshops, practice rooms and costume stores (shaded blue) and toilet and ancillary services (shaded green) relate to the

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Fig. 6.21 Heliopolis University, Shell of Peace. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.22 Crossed hands—inspiration for the plan of the Heliopolis University, Shell of Peace. Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.23 Site plan of the Heliopolis University, Shell of Peace with open forum (centre), enclosed conference hall (right) and core centre (left). Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.24 West (upper) and north (lower) elevations of the Shell of Peace, Heliopolis University, with open forum (centre), enclosed conference hall (right) and core centre (left). Reproduced from drawing by Michael Balz with permission from Michael Balz

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Fig. 6.25 Basement plan of the Shell of Peace, Heliopolis University, showing the link between forum, conference hall and core centre. Reproduced from drawing by Michael Balz with permission from Michael Balz

Fig. 6.26 Transverse and long sections of the Heliopolis University, Shell of Peace. The lower, long section suggests how the variable curvature of the shell surface will distribute sound more evenly. Reproduced from drawing by Michael Balz with permission from Michael Balz

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stage and link to the separate core building which incorporates administration offices and language workshops (shaded red). A key requirement for an auditorium is to have good acoustic properties so that the voice of a speaker or performer can be heard equally well by the whole audience. The coloured image of the long section in Fig. 6.26 reveals how the curved free-form of the shells enhances the acoustic performance of both auditoria. Surfaces with constant curvature tend to focus sound at one point, a focus, while leaving the rest of the audience struggling to hear. I have personal experience of this phenomenon having lectured in a room with semi-circular floor plan and hard wall surfaces: I could hear the reflected sound of my voice loudly and clearly at the front—the focus point—even when speaking quietly but students at the back kept asking me to speak up! However, here, the free-form of the shells has progressively varying curvature, so the voice of a speaker on the stage will not be focused. It will be reflected from the inner shell surface, as suggested by the blue lines, thereby providing a more uniform sound distribution that will also reach the audience at the back. The acoustic performance would be further enhanced if an absorbent surface such as cement-bound wood–wool panels were to be used as permanent shuttering, as in previous Balz/Isler shells. The two shells together form a large auditorium centred around a large, roughly oval, stage, like an amphitheatre. However, to provide additional flexibility, the northern half of the stage is designed to hinge upwards (shown in red in the long section Fig. 6.26), either as a single unit or as segments, to form an acoustically and climatically insulated vertical wall. The edge profile of the folded-up stage precisely follows the shape of the shells so that two independent auditoria result. A 2.5 m high cavity below the southern shell stage leads from the basement rooms and gives performers access to the stage by stairs or trapdoors. The flexibility of design is apparent from the suggested alternative arrangements for the Shell of Peace shown in Fig. 6.27, as follows: A—Sekem Forum (Fig. 6.27 top left)

In the Sekem Forum layout, the hinged stage/partition wall is in horizontal mode and the audience is on raked seating (shown yellow) below the shells in a covered space which is partially open to the external air. The audience is on both sides of the central stage which is used like an amphitheatre, for instance, for: • Devotion • Dance performance • Demonstrations.

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Unrealized Shell Projects

B—Conference hall (Fig. 6.27 bottom left)

In the conference hall arrangement, the central hinged dividing wall has been lifted and the space under the smaller shell (boundary shaded blue) is acoustically sealed and can be fully air-conditioned. The space within can be used for multimedia performance, lectures and presentations. The external space, which is open to the air but under the shade of the shell, can be used for informal meetings, meditation, etc. C—Divine service (Fig. 6.27 top right)

The layout for divine service (of any of the three religions accommodated in the Shell of Peace) is similar to that for the Sekem Forum. In this case, the central hinged stage/partition wall is also in horizontal mode. The congregation/audience is seated under the open shell, and activities such as services of religious devotion, opera performances and musicals are sheltered under the more enclosed shell. D—Concert hall (Fig. 6.27 bottom right)

For more formal orchestral concerts, the centralf dividing wall is again raised to create a fully enclosed hall, taking advantage of the acoustic benefits of the double-curved shell. The open-sided shell can also be subdivided to make smaller scale, more intimate outdoor performance and rehearsal spaces (shown green and yellow) using demountable partitions. The concept of creating a building designed to bringing the major monotheistic world religions together is not unique. A similar interfaith building “The House of One” has been proposed for Berlin and the foundation stone was laid on 27th May 2021 (House of One 2021) by Wolfgang Schäuble, the president of the Bundestag (Connolly 2021). The winning design by architects Kuehn Malvezzi—the result of an international competition in 2012—is to be constructed on the site of the former Petrikirche (St Peter’s Church) in Petriplatz, which was damaged during World War II and later demolished completely by the GDR. The new building “…will incorporate a church, a mosque and a synagogue linked to a central meeting space” (Sherwood 2021). Illustrations by the architects (Kuehn Malvezzi 2021) show a multi-storey, rectilinear, brick-faced building—this cladding material was recommended in the competition brief—which is quite unlike the reflectively embracing shells proposed by Michael Balz. A key difference in the two schemes is that in the House of One in Berlin the different faiths have independent spaces in which to worship, linked to a communal space: whereas in the Shell of Peace in Cairo the worship space is shared and the whole building is a communal facility. This seems more likely to encourage the faiths to find their similarities and overcome their differences.

6.6 Heliopolis University, Shell of Peace, Cairo, Egypt (2016)

a

b

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c

d

Fig. 6.27 Alternative auditorium arrangements a Sekem Forum (top left), b conference hall (bottom left), c divine service (top right); and d concert hall (bottom right) for the Shell of Peace. Reproduced from drawings by Michael Balz with permission from Michael Balz

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6.7

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Skateboarding Club (2016)

The extensive, relatively smooth, double-curved surfaces of reinforced concrete shells are very tempting for roller skaters and skateboarders, who have been known to try their skills on the Stetten shells. Large sports hall shell roofs, such as those at the Norwich Sports Village in the UK, have prominent signs warning people to keep off the roof in order to discourage such activity. In his seminal paper ‘New Shapes for Shells’ (Isler 1961), Heinz Isler proposed that shells could be form-found by mounding soil into a double-curved shaped hill or, the inverse, by excavating an appropriate double-curved depression in the ground. The latter was illustrated by a photograph of a free-form glass fibre-reinforced polyester liner for a swimming pool. This prompted Michael Balz to propose both ‘positive’ and ‘negative’ shell surfaces, for this skate park project for a skateboarding club. A plan view of the concept model, Fig. 6.28, shows the shell extending over an area of approximately 30 m  23 m overall. An oblique view, Fig. 6.29, shows more clearly the sinuous, three-dimensional multi-level continuous shell surface.

Unrealized Shell Projects

As revealed in the plan, Fig. 6.30, and section, Fig. 6.31, skateboarders are able to climb to the crest of the shell, 4.8 m above the ground, and sweep down to the lowest level at 2.5 m below ground by different routes. A small café on an intermediate floor is protected from adverse weather by the shell and provides an opportunity for spectators to view the skaters as they speed past during their descent. Michael Balz subsequently consulted the skateboarders to get their opinions about his design. However, in the end, despite having the three-dimensional physical model to help explain the spatial relationships described in the conventional plan and sections, the project came to nothing. The skateboarders felt unable to conceive what the quality of the skateboarding experience might be—either good or bad. They said that, normally, if they saw some likely skate run, they would just get on their board and try it. Although the shell Michael designed appears to be a demanding free-flowing surface ideal for boarding, perhaps one needs to directly experience the dynamics of skateboarding oneself to have the skill to design a challenging track! Nevertheless, there is still clear potential for such shells to be built at similar or larger scale.

Fig. 6.28 Plan view of concept model by Michel Balz of multi-level shell continuous surfaces for the skateboarding club. Photograph John Chilton with permission from Michael Balz

6.8 Street Bar, Stuttgart (2017)

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Fig. 6.29 An oblique view of concept model reveals the sinuous, three-dimensional multi-level continuous shell surface proposed for the skateboarding club. Reproduced from photograph by Michael Balz with permission from Michael Balz

6.8

Street Bar, Stuttgart (2017)

Given their striking and elegant visual appearance, it is surprising that free-form shells have not been used more frequently for smaller buildings such as bars or kiosks. They have the potential to provide an easily recognized brand identity, for instance for a particular beer or coffee shop chain. For example, Figs. 6.32 and 6.33 show a proposal by Michael Balz for a Stuttgart street bar of 12.0  8.0 m

covered by a shell of approximately elliptical plan. The form of the shell allows for a small mezzanine to be included above the bar. Although the plan indicates flat vertical glazed façades, in order to follow with the free-form nature of the shell, it would be possible to replace these with façades with a more curvilinear plan and/or inclined from the vertical. Although it would initially be expensive to manufacture the shuttering of the shell, repetitive use would reduce the unit cost.

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Fig. 6.30 Plan of the skateboarding club. Reproduced from drawing by Michael Balz with permission from Michael Balz

168 Unrealized Shell Projects

Fig. 6.31 Sections of the skateboarding club. Reproduced from drawing by Michael Balz with permission from Michael Balz

6.8 Street Bar, Stuttgart (2017) 169

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Unrealized Shell Projects

Fig. 6.32 Plan and elevations of a proposal for a street bar in Stuttgart. Reproduced from drawing by Michael Balz with permission from Michael Balz

6.8 Street Bar, Stuttgart (2017)

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Fig. 6.33 Alternative plan and sections of a proposal for a street bar in Stuttgart. Reproduced from drawing by Michael Balz with permission from Michael Balz

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6.9

6

Why Have These Projects Not Been Built?

The exhilarating and varied forms of these, sadly unbuilt, projects described in this chapter clearly reveal the huge potential for free-form reinforced concrete shells in modern architectural practice. There is no lack of design creativity so one must ask why are so few built? There are several possible causes, mostly, but not exclusively related, to perceived cost. By their nature, free-form shell surfaces are difficult to describe mathematically and, consequently, challenging to shape. In most cases, a precisely defined double-curved surface has to be assembled that is strong enough to support the weight of the concrete until it has set and gained sufficient strength to be self-supporting. Such formwork is generally assumed to be expensive, as standard modular flat systems cannot be used. For free-form shells, the formwork will potentially only be used once and then discarded. This can be both expensive in time and labour, and wasteful of materials—it is sometimes remarked that, effectively, two shells have to be built but just one remains in the end! The challenge, which to some extent had been solved by Heinz Isler and his preferred contractor Willi Bösiger AG, was to exploit thermal insulation panels as the final left-in-place formwork. However, this still needed to be supported on a system of flexible timber laths draped over specially profiled, simple timber sections nailed together or laminated beams supported on light scaffolding. As the eminent Swiss timber engineer, Julius Natterer has remarked to me “I’m building a shell which looks like an Isler shell. When you build [an Isler] shell, you build a shell in wood, then put concrete on it and then you take away the wooden shell. I’m just building the wooden shell. One building not two”. However, this argument can be challenged. To resist in-service loads, a permanent timber shell would need to be more substantial (and hence more expensive) than the temporary timber formwork supported on light scaffolding. Furthermore, a timber shell would need additional weather protection and maintenance, compared to a well-designed reinforced concrete shell, in order to achieve a similar building life. A further reason is the undeserved perception of high labour cost in actually forming a concrete shell. The extensive surface area needs to be placed, compacted and finished by a team of skilled workers. This is a relatively slow process. For instance, the concreting of the swimming pool shell roof at Norwich Sports Village, UK—a surface area of approximately 1300 m2 (Chilton 2000: 115–117)—took place over two days and at its peak required a team of around twelve operatives. Hence, in high-wage economies it can sometimes be supposed to be difficult to justify financially the construction of concrete shells, even though the labour cost of the shell pour is actually a relatively small proportion

Unrealized Shell Projects

of the overall project cost. The fact that, in the high-wage economy of Switzerland, Willi Bösiger AG were still building ‘standard’ Isler shells under licence until the early twenty-first century tends to refute the argument that labour cost is a significant factor against the construction of thin reinforced concrete shells. Nevertheless, shell construction can perhaps be more easily justified in lower-wage economies, such as India (like the proposed projects in Thane), where concrete shells are still being constructed. Although there are financial reasons put forward for the decline in use of reinforced concrete shells in Europe and the USA since the middle of the twentieth century, perhaps the most significant reasons are architectural—in particular the desire to move towards more transparency in building envelopes and the increasing use of steel in lightweight construction, including free-form gridshells. This has resulted in extensive areas of glazing being applied to steel roof structures, sometimes constructed with a single- or double-layer shell form. Even with the introduction of rooflights in the opaque concrete surface, it was not possible for shell roofs to compete with the fully open sky view of the glazed steel roofs. However, this full exposure has its disadvantages. There is some evidence that the fashion for extensively glazed roofs and façades is changing, due to increasing concern about their operational energy demands. Considerable effort is being expended to develop sophisticated (and therefore more expensive) glazing systems to reduce cladding heat loss in winter in cold climates and minimize solar gain in summer in hot climates. It is becoming more recognized that an opaque roof with strategically placed skylights with high thermal efficiency can give a more comfortable internal thermal environment, with lower energy and financial cost, while still providing more than adequate levels of daylight. Possible reasons for the decline of thin concrete shell construction were highlighted in a survey of engineers and architects carried out in the USA in 2005. This posed a number of questions, such as Are Thin Concrete Shells No Longer Being Built?; Why Have Thin Concrete Shell Structures Lost Their Popularity?; and Why Have Architects Lost Interest? (Meyer and Sheer 2005) The survey concluded that although reinforced concrete shells were still being constructed this was using standardized and industrialized air-inflated systems such as Bini Shells: landmark structures of architectural quality were rarely built since the 1970s. As well as mentioning their perceived high cost and that shells were considered unfashionable, passé or even heavy and brutalistic, the architects questioned suggested that alternative modern structural systems are more adaptable. They believed that it was easier to make geometric changes or future modifications to other systems and to instal the building services required in modern buildings.

References

To counter this view and revive interest in thin concrete shells, two short answers were propounded: to make concrete shells cheaper to construct; and to make them appealing (once more) to architects and their clients (Meyer and Sheer 2005). Advances in construction and materials technology have to some extent fulfilled the first of these requirements but the second is more problematic as it entails a (re)education of building professionals in the benefits of concrete shells so that they might propose them to their clients. In a keynote lecture at the International Association for Shell and Spatial Structures symposium, in Osaka, in 1986, Heinz Isler pointed out that for concrete shells “architectural questions are delicate and need more and better attention than normal building forms” (Isler 1986). He comments that shells are dominant structures, best located in open landscape where the form can be fully appreciated in context. Façades should be subordinate to the shell, and annex buildings should be separated by a “smaller connection which enters the shell through glazed units”. The shell proportions should be well balanced and the changing aspects of a sculptural shell considered early in the design. Finally, he comments that, where possible, inappropriate future enlargements or alterations should be avoided or even restricted under contract. Later, at a conference in Stuttgart, Heinz Isler countered many of the criticisms levelled at concrete shell design, in a paper that highlighted their positive properties and high efficiency (Isler 1994). He pointed out the simplicity of shells—that they are both the primary structure and a continuous, watertight, low-maintenance cladding in one surface; their minimum use of material—a thin surface, with reduced weight, needing smaller foundations, leading to reduced transport and material cost; their excellent load resistance and distribution properties—lower wind forces, direct load transmission to foundations and stiffness against horizontal forces such as earthquake. In addition, the minimal continuous surface greatly reduces thermal and air leakage from the building envelope, with consequent heating/cooling energy and cost savings. Although apparently heavy when compared to tensile structures, when their (usually hidden) ground anchorages are included the overall structural weight can be very similar. With these numerous positive attributes, it can be speculated that the low acceptance and uptake of reinforced concrete shells is due more to architectural fashion than any lack of efficiency. The demand has to come from architects and designers. During a conversation with Michael Balz in June 2018, I asked him why he thought people don’t build organic shells nowadays. His reaction was instant, saying “That’s a question which I cannot hear anymore because I’m always ready … I want to build shells!” (Balz 2018). He went on to

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comment that he felt that, today, it is normal for planners and people in general to mostly build cubic orthogonal architecture—a cultural style and aesthetic accepted worldwide, which leaves other forms at a disadvantage. Nevertheless, he was more optimistic for the future. His impression was that students in architecture schools are becoming tired of the rectilinear forms and are designing more with rounded shapes—perhaps driven by the wide availability of 3D-modelling computer software such as Rhino 3D and Grasshopper—where organic forms and concrete shells could play a role. We also touched on the subject of transparency and when I suggested that those same young designers were becoming more interested in gridshells, he countered by saying that their glazing was not so easy and was expensive. A further and important factor may be the current dearth of advocates of reinforced concrete architectural shell construction—Michael Balz excepted. In the mid- to late-twentieth century, those who built a large number of shells—Candela with Cubiertas Ala, Isler with Willi Bösiger AG, and Ulrich Müther with a succession of companies PGH Bau Binz, VEB Spezialbetonbau Binz, VEB Spezialbetonbau Rügen and Müther Spezialbetonbau GmbH—either had their own construction company or, in the case of Isler, had an ongoing very close relationship with one. It was clearly in their own interest to promote their expertise and the benefits of concrete shell construction. Since their demise, apart from standardized systems such as Bini shells, there is no specialist contractor in this field so there is no architectural shell construction industry!

References Abouleish I (2005) SEKEM: a sustainable community in the Egyptian Desert. Rudolf Steiner Press Abouleish I (2016) Die Sekem-Symphonie: Nachhaltige Entwicklung für Ägypten in Weltweiter Vernetzung, Überarbeitete und Stark Erweiterte Neuausgabe. [The Sekem Symphony: Sustainable Development for Egypt in Worldwide Networking, Revised and Extended New Edition]. Info 3 Verlag, Frankfurt/Main, Germany Balz M (1993) Organic forms in architecture: revolutionary alternatives to conventional rectangular and block building design mark architectural development. In: Indian Architect & Builder, August 1993, 96–102 Balz M (2018) Recorded conversation with John Chilton at the Balz House, Stetten auf den Fildern, 5 Jun 2018 Billington DP (2003) The art of structural design: a Swiss Legacy. New Jersey, Princeton University Art Museum p 143 Chilton J (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford, London, pp 130–134 Chilton J (2010) Potential unrealized? The shells Heinz Isler might have built... In: Zhang Q, Yang L, Hu Y (eds) Proceedings of the international symposium of the international association for shell and spatial structures (IASS), Shanghai, China, 8–12 Nov 2010. China Architecture & Building Press, Beijing, pp 3155–3162

174 Connolly K (2021) ‘House of One’: Berlin lays first stone for multi-faith worship centre. The Guardian, 27 May 2021. Available https://www.theguardian.com/world/2021/may/27/berlin-lays-firststone-for-multi-faith-house-of-one-worship-centre. Accessed 16 Sep 2021 House of One (2021) Groundbreaking Ceremony in May 2021. Available https://house-of-one.org/en/press/releases/groundbreak ing-ceremony-may-2021. Accessed 11 Mar 2021 Isler H (1961) New shapes for shells. Bull Int Assoc Shell Struct 8: [Paper C-3] Isler H (1986) Concrete shells and architecture. Bull Int Assoc Shell Struct 91:176–188 Isler H (1994) Shells of high efficiency, evolution of natural structures. In: Proceedings of the international symposium of the Sonderforschungsbereich 230; 3 Naturliche Konstruktionen; Heft 9, Stuttgart, pp 53–57 Malvezzi K (2021) House of One, Interreligious House of Prayer and Learning. Available http://www.kuehnmalvezzi.com/?context= project&oid=Project:14687. Accessed 11 Mar 2021

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Meyer C, Sheer MH (2005) Do concrete shells deserve another look? Concr Int 27(10):43–50 Seelos C, Mair J (2011) Hope for sustainable development: how social entrepreneurs make it happen. In: Ziegler R (ed) An introduction to social entrepreneurship: voices, preconditions, contexts. Edward Elgar, Cheltenham, UK, p 230 SEKEM (2020a) Heliopolis University for Sustainable Development. Available https://www.sekem.com/en/cultural-life/heliopolisuniversity/. Accessed 19 Jun 2020 SEKEM (2020b) The idea of holistic sustainable development. Available https://www.sekem.com/en/about/. Accessed 19 Jun 2020 Sherwood H (2021) Christians, Muslims and Jews to share faith centre. The Guardian, 21 Feb 2021, 19. Available https://www.theguardian. com/world/2021/feb/21/christians-muslims-and-jews-to-share-faithcentre-in-berlin. Accessed 11 Mar 2021 Wichmann W (2022) 150 Jahre Wallwitzhafen [150 years of Wallwitzhafen], Heimatverein für Dessau-Ziebigk [Local history society for Dessau-Ziebigk]. Available https://dessau-ziebigk.de/? page_id=142. Accessed 12 Aug 2022

7

Urban Space Structures

Abstract

This chapter presents Michael Balz’s vision for living in the city of the future, which he has developed over decades since his collaboration with architects Wilfried Beck-Erlang and Hans Lünz in proposals for the project ‘Stuttgart 2000’ in the 1960s.

7.1

Introduction

As Michael Balz pointed out in a lecture presented in Stuttgart in 2007, humanity has long held the ambition to erect outstanding and very special buildings. He remarked that, even in the Bible, Genesis 11, the children of Noah from the Ark wanted to build a city and a tower that reached up to the heavens. In the twentieth century, the 1950s and 60s represented an intensive period of recovery, renewal and rapid development after the Second World War and also a fertile period of architectural vision and innovation. In Japan, the Metabolism manifesto Metabolism 1960—a Proposal for a New Urbanism—was prepared by architects Kiyonori Kikutake (1928–2011), Kiyonori (Kisho) Kurokawa (1934–2007), Masato Ōtaka (1923–2010) and Fumihiko Maki (1928–) for the World Design Conference, held in Tokyo, in 1960. The declaration communicated their belief “…that human society must be regarded as one part of a continuous natural entity that includes all animals and plants … [and] … that technology is an extension of humanity” (Kurokawa 1977). Their model for a new urbanism, a fusion of megastructures and organic growth, included conceptual designs for floating cities and residential towers where living capsules were ‘plugged-in’ to the service core, as and when required (Sadler 2005; Lin 2010). For instance, Kisho Kurokawa, in 1961, presented conceptual designs for a Floating City, Kasumigaura, based on an extendable hexagonal planning

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_7

grid, which was to be built on a lake adjacent to the proposed New Tokyo International Airport at Narita; high-rise Helix City with structures based on the structure of DNA, also in 1961; and in 1965 a Linear City ‘Metamorphosis’, where “…nature and urban life exist in parallel” (Kurokawa 1977). Although never formally attached to the Metabolists, Arata Isozaki (1931–2022), in 1960, proposed the Joint Core System of megastructures comprised towering cylindrical cores linked by deep multi-level trussed bridge-like structures carrying offices and flats over the district of Shinjuku in Tokyo (MoMA 2021). For the locale of Shibuya, Tokyo, in 1962, he proposed the City in the Air (also known as Clusters in the Air). Here, tree-like megastructures soared at high level over the existing urban fabric with capsules springing either side of progressively cantilevering arms. In Europe, following a visit to Brazil in 1958, the German-born artist Walter Jonas (1910–1979) conceived ‘Intrapolis’ described as “…a funnel-shaped city, his vision for a new, dignified and environment-friendly urbanism” (Walter Jonas 2021). His ideas, published in the book Das Intrahaus—Vision einer Stadt (The Intrahaus—Vision of a City) (Jonas 1962) were recognized internationally, although no example was ever built. Accommodating up to 2000 residents, Jonas’s funnel-shaped towers were to stand on a single wide column base. They were projected to be about 100 m high with a diameter of 150–230 m at the top, with an inverted conical funnel-shaped void in the centre opening at an angle of approximately 90° (Urfer 1999). Terraced residential units mainly faced inwards towards a green planted core. Walter Jonas was also a founding member of Groupe International d’Architecture Prospective (GIAP) together with Yona Friedman (1923–2020) who proposed the Ville Spatiale as a system of large-scale multi-layer spatial structures elevated above the existing urban fabric, which could be populated by residents on a self-planned basis. This was designed to avoid the demolition of existing buildings,

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promote a more compact city and allow urban expansion without further encroachment on the surrounding countryside (Friedman 2021). In the USA, the renowned innovator and inventor Richard Buckminster Fuller (1895–1983) developed proposals for megastructures on behalf of the businessman Matsaturo Shoriki. These included a two-mile-high tetrahedral tower (1966) and, in 1970, a city for one million inhabitants designed to float in Tokyo Bay. The tetrahedral form of his design was chosen by Fuller due to its structural stability and its large surface area related to its volume (Gorman 2005: 187). In the United Kingdom, Archigram’s Peter Cook proposed the Plug-In City, in 1964. A megastructure that was to “…extend across Britain and across the Channel to continental Europe…” (Sadler 2005). It was in this international context that Michael Balz and his colleagues first developed their proposal for urban space structures.

7.2

Project ‘Stuttgart 2000’ (1965–1982)

The project ‘Stuttgart 2000’ on which Michael Balz worked in collaboration with architects Wilfried Beck-Erlang (1924–2002) and Hans Lünz was presented successfully at the Grand Prix International d’Urbanisme et d’Architecture, in Cannes, France, in 1970. The project addressed two important issues for the city of Stuttgart: the need to reduce the spread of urban development engulfing land considered to be valuable for agriculture or forestry; and the need to

Urban Space Structures

improve climatic conditions for residents within the geological bowl in which the city finds itself, which results in frequent smog conditions (Beck-Erlang 1994). The project can also, perhaps, be seen as a precursor of the ongoing Deutsche Bahn AG infrastructure project Stuttgart 21, which was first presented to the public in 1994 (Novy and Peters 2012). To ease the problem of lack of air movement, the remarkable and dramatic proposal assumed that the 60 ha of land occupied by rail operations in the centre of the city would become available for redevelopment either by relocating rail operations outside the central bowl or by burying them underground—a transformation that is currently being realized partially with the Stuttgart 21 project (Ingenhoven 2021). The land released would be transformed into a lake and landscaped gardens to change the micro-climate in the geological bowl and induce more air movement. To solve the housing need, it was proposed that buildings should be located in the air to preserve the landscape. Interlinked, tree-like, high-rise structures up to 300 m high were to be constructed on the hills surrounding the city, Fig. 7.1. It was argued that the minimal tower building footprint, when compared to that required for more conventional buildings in order to accommodate the same functions, and the location of transportation routes and car parking below ground, meant that most of the land beneath the megastructures would be relatively undisturbed and could be used for agriculture, forestry and/or recreation. Vertical circulation and distribution of services were incorporated in the core towers, Fig. 7.2. Public functions

Fig. 7.1 Proposal for ‘Stuttgart 2000’ city centre lake and housing in the air. Reproduced from image by Michael Balz with permission from Michael Balz

7.2 Project ‘Stuttgart 2000’ (1965–1982)

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Fig. 7.2 Cross-section of proposed high-rise tree structure for ‘Stuttgart 2000’. Reproduced from drawing by Michael Balz with permission from Michael Balz

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were accommodated on a broad platform, located 100 m above the ground, linked by panoramic promenades between the towers, which would incorporate shopping facilities. Lower floors of the towers were reserved for commercial and administration offices. The floors above the promenade deck were to be used for individual dwellings on terraces, apartments, leisure and childcare and, at the highest level, hotels bars and restaurants.

7.3

Cityscape Visions

Over the intervening years, Michael Balz has continued to develop this concept. The assimilation of his organic building forms, modern industrial mass production techniques and his vision for their future application in urban space structures were outlined in his contribution “Organische Bauformen und Stadtraumvisionen” (Organic Building Forms and Cityscape Visions) in the publication, Ideen zum Städtebau: Das Stadtquartier der Zukunft (Ideas for Urban Development: the Urban Quarter of the Future) (Balz 2005). A translated and edited version of the vision he presented is recounted and examined in the following sections.

7.4

Building Today

After a brief introduction to his ideas about organic architecture and description of the prototype living shell, the Balz House described here in Chap. 4, Michael Balz offered his critique of the current state of the housing industry in Germany. It can be said that the same arguments almost certainly apply in most countries in the world today. To begin, he observes that in many countries housing is still being built using traditional construction methods, placing heavy blocks of material on top of each other—stone, brick and concrete with wet mortared joints. Multi-storey flats are built with prefabricated walls and floors/ceilings, generally with very heavy concrete materials. Further, most of this construction work takes place outdoors, where it is subject to the vagaries of the weather, using traditional (usually slow) manual methods. Consequently, he considers current building costs to be too high and construction times too long. He identifies a lack of imagination in the design of buildings in towns and suburbs all over the world, indicating that they generally have a box-like appearance both inside and out. In response, he proposes that alternatives could (or better said should) be developed, which more specifically reflect life in the twenty-first century. To some extent, the use of traditional materials and architectural styles results from the marked conservative attitudes exhibited by both house builders and house buyers. Builders are generally resistant to change: they prefer to continue with the ‘tried

Urban Space Structures

and tested’ building techniques. Their workers are familiar with these techniques and the builders can be reasonably confident that the houses they build will sell. Equally, the majority of buyers tend to prefer ‘traditional’ housing, aesthetically similar to the familiar existing urban environment. However, there is a converse argument that, in reality, house buyers have little choice in what they can buy. Generally, they can only purchase what is on offer from the builders: that is houses built from conventional construction materials and of traditional architectural style. There is an obvious inconsistency, here, when compared to the attitude of the typical car buyer—frequently the same person as the house buyer—who expects to be offered, and have choice of, the most up to date in design technology, style, performance and comfort. To obtain a dwelling equivalent in sophistication to the latest model of automobile—what many would call a ‘non-conventional’ house—one usually has to resort to self-build. Noting that full industrialization of housing construction is almost non-existent—at least when he was writing in 2005—Michael Balz suggests that the advantages of industrial design, and corresponding low-cost mass production, are to a great extent lost to the industry. It would clearly be feasible to industrialize by further applying the experience of manufacturing industries such as car production and aviation. The ongoing and urgent need for additional housing provision is also stressed. He draws attention to the permanent housing shortage in most countries, including those with highly developed economies, which occurs as a consequence of factors such as population increase and/or immigration, political and social problems, and as an incidental effect of wars and other conflicts. Sadly, homelessness is evident even in first-world developed countries. It is remarked that in historical times towns and cities tended to flourish close to rivers, where good agricultural land was available in the vicinity, and where suitable conditions of soil, climate and topography predominated. On the other hand, it is argued that such limitations do not necessarily apply today. Modern means of transport allow greater flexibility in location of urban areas and new construction methods facilitate developments in more severe climates. Michael Balz concludes that, today, it should be possible to build settlements wherever there is an acceptable climate. Settlements are no longer dependent on there being a hinterland in close proximity that is suitable for agriculture and food production, although this proximity may still be desirable to reduce transportation costs and consequent carbon dioxide emissions. Variation in land topology is particularly easy to deal with for buildings that span across the landscape. Level changes can be accommodated easily by varying the number of floors below the platform level connecting individual pylons.

7.6 Space Above the Land

With the impact of the global climate emergency, the protection of agricultural and ecologically important landscapes from intensive urban development is vital today. However, there is a counterargument that the energy required for transportation of goods and personal travel to new urban neighbourhoods will increase carbon emissions with an adverse impact on world climate. This suggests that expanding cities by building at high level over existing urban areas could be the most advantageous solution.

7.5

Opportunities for a New Construction Industry

Given his critical appraisal of the state of the building industry, Michael Balz believes that there are many opportunities for reform, for instance, by potentially being organized more along the lines of manufacturing industries or the restructuring of other industries such as the arms industry. He notes that the latter is a huge worldwide industry, which employs many talented designers and engineers, whose efforts could perhaps be better directed to solving society’s housing needs in the twenty-first century. Internationally, car production has achieved a very high standard, with the ability to produce technologically advanced vehicles of the same model with different specifications assembled on the same production line, using just-in-time delivery methods. There is great potential for these production approaches to be used in a modified form for the industrial manufacture of the living cells described in Chap. 2. Equally, fully furnished caravans and mobile homes are currently fabricated in quantity. The techniques used in their production could logically be applied to the proposed modular dwelling units. Shipping containers of standard sizes are manufactured in large numbers and used to transport goods all over the world. Increasingly, once they have reached the end of their useful life for their original intended purpose, architects are adapting these containers, for instance as small housing or shopping units. Additionally, industries producing railway trains, luxury coaches and ships have extensive experience of designing and fitting out interiors to accommodate a variety of geometries, which is also applicable in the crafting of prefabricated housing units. The aircraft industry devotes an enormous research effort into perfecting lightweight construction systems to reduce fuel consumption, in order to increase the range of their aircraft and increase payloads. Technology transfer can exploit their experience in the utilization of lightweight materials to create efficient and strong architectural systems and structures. The same applies to the technology developed for space exploration where any saving in weight is even more critical. Furthermore, anticipating the construction needs of his proposed spatial urban structures, Michael

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Balz draws attention to the very high standards and wide experience that civil engineers have in the building of bridges, masts and towers, in particular those utilizing lightweight materials, and innovative and non-conventional structural systems. A final important issue that he raises is construction safety. The building industry generally has a poor record in this respect. However, by moving construction jobs, wherever possible, from outdoor building sites into an indoor sheltered factory environment, where there is better control of both quality of manufacture and health and safety of operatives, will make the industry more attractive to skilled workers.

7.6

Space Above the Land

World human population continues to grow—from 6 billion in 1999 to 7 billion in 2011—and passed 8 billion in February 2023. Yet it took the whole of human history until around 1800 for the world population to reach one billion, which is equivalent to the increase in just 12 years from 2011 to 2023 (Worldometer 2021, United Nations 2018a). At the same time, there has been migration to urban areas. According to United Nations data, the annual percentage of population at mid-year residing in urban areas has increased from 33.8% in 1960 to a projected 56.2% in 2020 (United Nations 2018b). The daily increase in world population of around 220,000 people is equivalent to creating a new small city each day, and the increasing movement from rural to urban communities leads to expansion of cities onto surrounding agricultural land. Yet there is a need to preserve fertile land for agricultural production to feed the increasing population. Hence, there are indications that urban planning in the future will have to search for new ways of spatial management and new approaches to modelling the urban landscape to accommodate larger populations at higher density. Conventionally, the response has been to build densely packed high-rise apartment blocks on individual relatively small private plots of land. In most cases, movement between them is usually only possible at street level. The land surface is almost totally covered, leaving little space for natural greenery, while, at ground level, pedestrians are required to dodge between road vehicles and breathe poisonous exhaust fumes, Fig. 7.3a. The alternative proposed by Michael Balz, Fig. 7.3b, imagines more substantial towers on larger building footprints, at greater spacing, with elevated cross-connections for pedestrians, cyclists and small electric vehicles. In this way, considerable advantages in space utilization can be achieved—there is more green space and pedestrians are separated from traffic and noxious fumes.

Fig. 7.3 a Conventional high-rise towers on multiple plots with connection only at street level with little or no open space or greenery; b linked towers on more dispersed bases, connected at high level, permit greening of the urban landscape. Reproduced from drawings by Michael Balz with permission from Michael Balz

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7.8 Supporting Bridge Structures

In his article, Michael Balz also proposes that it would be advantageous for the development of the new city if the land on which the city is to be built did not belong to private individuals, but to the community. He is convinced that the earth belongs to us all just like the air and water.

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space-enclosing elements can be produced better in large moulds and formwork than cubic and rectangular designs. In this way, the static advantages of double-curved shells can be exploited to the full.

7.8 7.7

Housing Units for Spatial Urban Structures

When compared to the design evolution of cars and aircraft, which has occurred over the last hundred years or so, housing design has changed little in centuries. One exception, in cooler climates in particular, is the great improvement in thermal performance due to developments in insulation materials and glazing systems. However, to address the general deficiency in housing innovation, and following the precedents such as the mass production of caravans and cars, Michael Balz has investigated possibilities for the production of living cells, such as those described in Chap. 2, in large quantities. Recognizing the difficulty of transporting large shell structures, he has developed basic modules with structural frames approximately the size of common shipping containers and mobile homes, having maximum dimensions of 3.5 m in width, 7.0 m in length and 3.0 m in height. To accommodate the installation of services, these modules include a double floor. To provide a range of design alternatives, the individual modules can be easily assembled into various configurations to create self-supporting housing units of up to twenty room cells with a maximum height of three storeys, Fig. 7.4. In order to deliver the organic character that he believes would be visually refreshing after the long period of the human race living in predominantly rectangular box-like buildings, the modules could be fitted out with external cladding of lightweight but strong curvilinear shells—just as aerodynamic double-curved body panels are bolted on to the structural frame of a modern car, Fig. 7.5. However, the shells could also be designed to contribute to the structural stability of the overall system and they would also improve the aerodynamics of the housing units. Their smooth curved form would reduce the wind resistance and, hence, the wind loads transferred to the supporting spatial structure. Consequently, structural sizes could be reduced and less material would be needed. Internally, the biomorphic character would be reflected by organically shaped interior design and furnishings. To enrich and further free up the architectural form, curvilinear terracing elements could also be added to the exterior of the housing units, cantilevered from the structural frames. Other techniques can be adapted from container and tank construction. Michael Balz’s initial investigation of series production has shown that organically shaped, shell-like

Supporting Bridge Structures

If future urban space structures are to touch the land lightly, appropriate supporting structures will be required. In the mid-twentieth century, there were conceptual designs using space frames, such as the City Tower, Philadelphia (1956), by Louis Kahn (1901–1974) and Anne Griswold Tyng (1920–2011) (Ayad 1997) but these generally had a substantial building footprint. Michael Balz has proposed an alternative means of support, exploiting the long-span suspension and cable-stayed bridge construction technology that is well established in the twenty-first century. In those bridges, by utilizing the efficiency of high strength materials in tension and concentrating the compressive forces into a limited number of towers or pylons, heavy traffic loads are carried over spans now approaching two kilometres—for instance, the Akashi Kaikyō Bridge in Kobe, Japan, which has a main span of 1991 m. He plans to use pylons 190 m high, spaced at a distance of 220 m to support a system of cables and bridge-like decks. A number of main decks connecting adjacent pylons are suspended at approximately mid-height of the towers and are linked to form a horizontal girder, which is suspended from the cable system, Fig. 7.6. Elements of cable-stayed bridge technology are used for stiffening. The whole structure is prestressed to minimize deflections and vibration of the structure under imposed loads and when subject to wind effects. Assuming a hexagonal ground plan arrangement is used as the basis for future enlargement, as shown in Fig. 7.7, a new pylon can be added to the overall system by connection to neighbouring towers with one or two arms. Each pylon supports three arms with horizontally suspended footbridges, 10.5 m wide, at a vertical spacing of 12 m. From these, residents are able to access the living cell groups which are anchored to the decks, shown in elevation, plan and typical section in Figs. 7.8, 7.9 and 7.10, respectively. Figure 7.11 reveals the concept in three dimensions as a representational physical model. For an individual tower, because the majority of load is the self-weight of the structure, the three arms are approximately in balance. However, non-symmetrical loading resulting from wind loads, possible variable disposition of the living cells and operational loads may induce bending and torsion of the tower. To provide stability for a single tower, this can be resisted by designing the core as a vertical cantilever, as in a normal high-rise tower, or perhaps by the addition of vertical or inclined outrigger cables to anchor the

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Urban Space Structures

Fig. 7.4 Modular residential modules supported above ground on metal structures. Reproduced from drawing by Michael Balz with permission from Michael Balz

7.8 Supporting Bridge Structures

183

Fig. 7.5 Model of organic-form lightweight modular residential modules. Reproduced from photograph by Michael Balz with permission from Michael Balz

Fig. 7.6 Pylon and cable support system for modular residential units with connected decks forming a deep beam linking the towers. Reproduced from drawing by Michael Balz with permission from Michael Balz

184 7 Urban Space Structures

7.8 Supporting Bridge Structures

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Fig. 7.7 Plan showing extendable hexagonal layout of the pylon and habitable bridge deck system. Reproduced from drawing by Michael Balz with permission from Michael Balz

7

Fig. 7.8 Modular room cells on suspended decks. Reproduced from drawing by Michael Balz with permission from Michael Balz

186 Urban Space Structures

Fig. 7.9 Plan of deck with alternative layouts of the modular room cells. Reproduced from drawing by Michael Balz with permission from Michael Balz

7.8 Supporting Bridge Structures 187

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Fig. 7.10 Section through the modular room cells. Reproduced from drawing by Michael Balz with permission from Michael Balz

188 Urban Space Structures

7.8 Supporting Bridge Structures

Fig. 7.11 Concept physical model. Reproduced from photograph by Michael Balz with permission from Michael Balz

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Fig. 7.12 Vehicular (blue) and pedestrian (red and orange) circulation routes for extended tower system (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr)

190 Urban Space Structures

7.9 Feasibility of the Megastructures

ends of the cantilevered arms to the ground. Where two towers are connected, they effectively form a suspension bridge along one axis with balancing cantilevers but the effect of wind load is similar for crosswinds. A more stable system is created when three towers are connected. However, the most stable system occurs when six towers are linked to form a continuous hexagonal ring, as shown in Fig. 7.7. Following heavy loss of life in events such as the terrorist attack on the twin towers of the World Trade Centre in New York on 11 September 2001 and, more recently the Grenfell Tower fire in London, on 14 June 2017, there is a growing awareness of the need to provide multiple means of evacuation from high-rise buildings for use in emergencies. In a normal high-rise tower, the only means of evacuation is vertically, usually down one or more fire-protected staircases. During a fire or other calamity, lifts are usually reserved for use by the emergency services only. Where there are two or more towers connected, the proposed system clearly has the potential to address the need for multiple evacuation routes: each is effectively linked to other pylons by ‘skybridges’, at one or more levels. This provides occupants with several alternative means of escape, both horizontally and vertically down adjacent towers (Wood 2010; Oldfield 2012). Skybridges have already been implemented successfully in, for instance, the Petronas Towers in Kuala Lumpur (1996), designed by César Pelli (1926–2019) and, more recently, in the American Copper Buildings, in New York, (2017) designed by ShoP Architects. To facilitate construction of the residential units, one of the lifts inside the pylon could be dimensioned to enable components of the living cells to be transported from the ground to each floor—after construction this becomes the goods lift. Alternatively, a crane could be located at the top of the tower to lift cells, as shown in the Plug-In projects of Archigram, or hoisted up directly from the decks. Equally, the bridges are made wide enough, to enable cells to be moved from the pylon to their mounting positions on the deck. The pylons accommodate vertical transportation of residents, by means of escalators and various lifts with different speeds, the supply of water, electricity, heating, information systems, disposal of waste, etc. All services are routed to the residential units through the structure of the street decks. Within the residential trees, there is only pedestrian access, with small electric vehicles for the transport of goods. Access to the megastructures is by road and rail networks at ground level with stations near the pylons and underground parking for private vehicles, Fig. 7.12. It is suggested that extensive planting with an integral irrigation system should be used to landscape the various connecting decks, which can be regarded as panoramic viewing routes. A similar concept has been applied in the Bosco Verticale, in Milan, by Stefano Boeri Architetti

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(Woodman 2015), where the residential towers have heavily planted balconies. The foliage will help to improve air quality, and it is expected that the planting will also encourage birds and other wildlife to populate the decks. There is also potential to use areas of the suspended decks for urban agriculture, to provide fruit and vegetables for the living cell residents, for example, as demonstrated by the 1200 m2 urban farm on the roof of the Collège Eugène Delacroix in the 16th arrondissement of Paris (Agripolis 2021). If this system of settlement becomes well established, it is possible that schools, administration offices, leisure and shopping facilities, crafts, service facilities, etc., can also be settled within the structures. The structures presented here typically contain approximately 53,000 square metres of living space on each pylon for a total of around 2000 residents. The original natural landscape or the old city beneath this superstructure is only touched by the bases of the pylons. Hence, by using the space above ground, it can be kept free from direct settlement and potentially create additional productive agricultural capacity.

7.9

Feasibility of the Megastructures

In 2014, an investigation into alternative structural possibilities for the proposed megastructures was carried out by Theresa Nettekoven, a master’s student at the Technical University Berlin (Nettekoven 2014). These initially assumed structures, each with 56 storeys, with a total height of 168 m, standing on a hexagonal base with side length of 16 m. Each tower had an ellipsoid atrium at its centre. The report highlighted the structural challenges posed by the need to support a building of 56 storeys, with three large cantilevers, 24 m deep at their extremity, on a base having a maximum width of 32 m, while reserving sufficient space for vertical circulation—stairs, escalators and lifts (Nettekoven 2014). Following preliminary load assessment, the base area was increased. Three alternative structural types were considered. The first had a central reinforced concrete pylon as the main load-carrying element—a partially suspended structure based on bridge technology for the upper floors combined with curved compression elements supporting the majority of load from the lower floors Fig. 13a. Floor loads were routed to the primary elements by deep trussed transfer structures at every fourth floor. Although found to be feasible from the structural standpoint, this solution was rejected due to the 25% reduction in usable space required to accommodate the truss system. After discussion with Michael Balz, a second alternative was proposed for the primary structure. This consisted of an arrangement of six

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wall planes—three each of two different types—cranked around a central void Fig. 7.13b. These planes were designed to transfer vertical loads from floors directly to the base and also to brace the building against lateral loads. In this case, with the smaller floor spans between primary wall planes, storey high trusses at 11 m centres, with maximum 54 m span, were considered at every fourth floor. After further discussion, a third alternative was proposed to free up internal planning and create more direct load paths to the foundations. Here, the massive concrete walls were replaced by a more dispersed steel lattice rib structure with an increased number (eighteen) of primary support planes of four different types Fig. 7.13c. At the same time, the outer diameter of the base was also increased to 67 m. Finally, the estimated steel and concrete consumption of the three structural solutions per cubic metre of building volume was used compare their efficiency in relation to each other and to typical high-rise building construction. This concluded that the first proposal was the most efficient but this did not allow for the reduced usable space. Once this was taken into account the final, dispersed steel structure was most efficient, but consumed about 10% more steel and concrete than a typical high-rise building (Nettekoven 2014). This suggests that further dispersion of the structure to reduce floor spans, perhaps with branching columns in the lower half of the building and converging struts in the top half—like a series of steel concentric lattice shells—could potentially lead to an even more efficient solution.

7.10

The Spatial City

With such dominant buildings in the rural or urban landscape, the appearance of the supporting primary structure, Fig. 7.14, will influence the overall impression of the building as much as the living cells themselves. In addition, these structures have the potential to create completely new distinctive skylines, which could become a symbol for the spirit of the new century. With this type of settlement and construction, it is possible to develop unusual striking building developments all over the world, for instance, across mountain valleys, on mountains, in harsh climates such as desert landscapes and zones of perpetual frost, in shallow waters Fig. 7.15, in coastal areas and in holiday towns, etc. Combinations of such living cells are conceivable under large pneumatic shells in extreme climatic zones, such as the 2000-m span “City in the Arctic” proposed in 1971 by Atelier Warmbronn (Frei Otto, and Ewald Bubner), Kenzo

Urban Space Structures

Tange + Urtec and Ove Arup & Partners (Edmund (Ted) Happold and Peter Rice) (Meissner and Möller 2005). Alternatively, for existing urban areas Richard Buckminster Fuller confirmed the feasibility of constructing a 1.6-km-high, 3-km-wide tensegrity dome to cover 50 blocks on Manhattan Island, New York (Pawley 1990), under which such megastructures could be accommodated. Provided that the sociological and psychological questions of this type of housing are assumed to be resolved, which are beyond the remit of this discussion, the following criteria are considered critical for the technical solution of the supporting structures of such cities: 1. Durability of the main materials—This is important in order to minimize the need for maintenance or replacement of components at high level 2. Sensitivity to partial destruction—The system needs to be robust avoiding the possibility of progressive collapse 3. Assembly and fastening with simple methods—For working at height, speed of construction of the supporting tower and bridge system is highly desirable 4. Access to natural sunlight for all living cells—This engenders improved health and well-being for the residents 5. Development of the transport and fastening possibilities of the cells—An external method of transportation, for instance by crane on the tower or hoist from the deck structures, would avoid the need for a very large lift in the tower. Plug-in systems would facilitate replacement of damaged or obsolete units 6. Replacement and renewal of the cells—planned refurbishment and upgrading; opportunities for recycling need to be explored 7. Preventive fire protection for the star construction— Compartmentalization can be enhanced by the physical separation of the living cells but multiple means of escape will be required, especially from the extended cantilever arms if not connected to an adjacent tower 8. Development of internal and external circulation 9. Installation of all services expected by residents in current and future society—The tower and decks need to have the flexibility to provide space for possible new utility services 10. Heating, cooling and air conditioning of the cells and public spaces—The separation of living units increases their surface area. This may require increased insulation to minimize energy use but provides additional opportunities to exploit renewable energy sources. For instance, the tower and bridge structures could be clad in photovoltaic panels and/or solar thermal collectors.

The Spatial City

Fig. 7.13 Alternative structural solutions investigated by Theresa Nettekoven with: a central pylon trussed cantilever decks; b radial concrete wall planes; and c dispersed steel lattice ribs. Reproduced from drawings by Theresa Nettekoven with permission from Theresa Nettekoven

(c)

(b)

(a)

7.10 193

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Fig. 7.14 Pylon supporting structure seen from ground level (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr)

Fig. 7.15 Photomontage of spatial city introduced into marginal land in an existing landscape (design concept by Michael Balz reproduced from drawing by Dipl.-Ing. Henning Dürr with permission from Michael Balz and Henning Dürr)

7.12

7.11

Is This the Future for an Urbanized Society?

Concerning the Responsibility of the Designers

Michael Balz believes that the architects and engineers of these megastructures accept a very high level of responsibility. From the economic point of view, the manufacturing facilities proposed can only be justified if large production runs are delivered. The form of such structural systems is decisive for the environment, which is the home of the people. Also, the form and function of these buildings have a great influence on the whole life of their inhabitants. Hence, he considers that research and development into the feasibility of such urban construction systems are more important than car design, more important than space flight and also more important than all kinds of fashionable consumer products. He imagines that, if we consider the life needs of the people of today as our mission, the technical possibilities of today as our tools, and if we consider the physical laws of nature in our design work, then we have opportunities for the development of sustainable cities and living spaces that do not have to fear a comparison with the building culture of the past, and which guarantee a dignified life for future generations.

7.12

Is This the Future for an Urbanized Society?

Although Michael Balz’s urban space structures are proposed as a possible solution to the future housing needs of an increasingly urban society, there are some questions that might be raised and potentially conflicting arguments that need to be aired concerning the desirability of constructing such megastructures in the twenty-first century. For instance, topically, with the COVID-19 pandemic that originated in Wuhan, China, in late 2019, and the restrictions on society that have ensued in some, mainly highly developed, countries, there has been a tendency for people to migrate away from cities, which are understandably perceived as hotbeds of the virus. Over the duration of these restrictions, people have become accustomed to working at home—greatly assisted by video conferencing used widely for one-to-one meetings right up to international conferences. They have been avoiding public transport and many have embraced a more relaxed rural or small town/city way of living. Such a sudden, and possibly permanent, shift of societal attitudes could work against future large-scale extension of urban environments. There is also increasing concern for the environment alongside changes to global climate that threaten the viability of some of the world’s most populated cities before the end of the twenty-first century. Increasing world population

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requires existing food production systems to intensify their production while an increasingly urbanized society is consuming the agricultural land that supports it. Rising sea levels threaten to flood some of the major cities, potentially requiring their relocation, or increased flood protection, or elevation of the city above expected sea levels. Michael Balz’s proposed urban vision addresses some of these concerns, as the impact on agricultural land can be minimized and the pylons can be built in the sea or inundated land and designed to accommodate to rising sea levels. Conversely, even though, apart from the pylons, the proposed urban space structures potentially use efficient tensile structural systems, considerable physical and financial resources will be required to construct the megastructures. These will also have a major visual impact on the regions that accommodate them, potentially disrupting the natural beauty of the landscape and ecological balance. One wonders how desirable it is to develop large communities in remote regions even if there is, in theory, minimal physical disturbance to the land surface once the towers and bridges have been constructed? In large cities, however, the rationale for such megastructures is perhaps more persuasive. Super-tall skyscrapers and high-rise buildings linked by skybridges are becoming more commonplace. In April 2021, architect Kohn Pedersen Fox completed the Bundang Doosan Tower in Seoul, South Korea, which has two 27-storey blocks rising to 130 m. The towers are linked by a four-storey high skybridge at a height of 100 m, with floor plans of 4000 m2 including open and interactive office spaces (Kohn Pedersen Fox 2021). Safdie Architects, established by Moshe Safdie (1938–) designer of the highly innovative modular housing of Habitat’67 in Montreal, also has several projects incorporating skybridges. The Raffles City Chongqing complex in China, which was completed in 2020, is a case in point. Located at the confluence of the Yangtze and Jialing rivers, it consists of a group of eight towers, six of which are 250 m in height. The remaining two rise to 350 m. Four of the shorter towers are connected at the top by a 300-m-long skybridge, called the Crystal Skybridge. Similar to the proposals made by Michael Balz in his conceptual designs, the glazed elliptical tube bridge is inhabited, containing “… gardens, bars, restaurants, a clubhouse for the residents and a lobby for a hotel, all located 250 m in the air” (Block 2020). The same architects were responsible for the megastructure Marina Bay Sands Hotel and SkyPark in Singapore (2010) where a similar skybridge links three 57-storey high towers. As commented by the architects for this project, “Projects of scale and density can easily be overbearing and imposing, impenetrable and seeming to turn their back on the cities of which they are a part” (Safdie Architects 2020).

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A further project by Safdie Architects, proposed in 2021, aligns more closely with Michael Balz’s vision for linked towers over open urban landscape. The proposed ORCA mixed-use development and park in Toronto, Ontario, Canada, comprises eight high-rise towers interlinked by skybridges that incorporate amenities for the tower’s residents. Located adjacent to a 10.5 acre (4.25 ha) public park, to be created by decking over a 100 m wide railway corridor, the towers are raised on piloti. Thus, views across the site are preserved and additional cross-site routes are opened up for pedestrians and cyclists (Safdie Architects 2021; Block 2021). This repurposing of railway land also brings to mind the proposals of the ‘Stuttgart 2000’ project. At the time of writing, mid-2021, it seems unlikely that Michael Balz’s visionary urban space structures will be realized in the near future, in precisely the form he envisages. However, it is apparent that several aspects of his proposals are being incorporated into some of the present, more innovative designs for high-rise buildings.

References Agripolis (2021) Paris 16e arrondissement—Collège Eugène Delacroix. Available http://agripolis.eu/project/paris-16-college-delacroix/. Accessed 12 Feb 2021 Ayad IE (1997) Louis Kahn and space frames. In: Gabriel J-F (ed) Beyond the cube: the architecture of space frames and polyhedra. Wiley, New York, pp 127–146 Balz M (1994) Modular structures in organic design. In: Höller R, Hennicke J, Klenk F (eds) Application of structural morphology to architecture, proceedings of 2nd international seminar on structural morphology, University of Stuttgart, pp 1–10 Balz M (2005) Organische Bauformen und Stadtraumvisionen [Organic building forms and cityscape visions]. In: Ideen zum Städtebau: Das Stadtquartier der Zukunft [Ideas for urban development: the urban quarter of the future] Schriftenreihe des Verbandes Deutcher Architekten- und Ingenievereine, Band 3, 113–122 Balz M (2018) Recorded conversation with John Chilton at the Balz House, Stetten auf den Fildern, 5 Jun 2018 Beck-Erlang W (1994) Project Stuttgart 2000. In: Höller R, Hennicke J, Klenk F (eds) Application of structural morphology to architecture, proceedings of 2nd international seminar on structural morphology, University of Stuttgart, pp 11–20 Block I (2020) Safdie Architects completes “horizontal skyscraper” at Raffles City Chongqing. Available https://www.dezeen.com/2020/ 06/25/safdie-architects-the-crystal-raffles-city-chongqing-architecturre/. Accessed 26 Jun 2020 Block I (2021) Safdie Architects designs interconnected housing blocks alongside park over train tracks. Available https://www.dezeen. com/2021/06/16/safdie-architects-orca-development-toronto/?utm_ medium=email&utm_campaign=Daily%20Dezeen&utm_content= Daily%20Dezeen+CID_61b1d939f84d3797d2cb2c2c6a28019a&u tm_source=Dezeen%20Mail&utm_term=Safdie%20Architects%20 designs%20interconnected%20housing%20blocks%20alongside% 20park%20over%20train%20tracks. Accessed 18 Jun 2021

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Friedman Y (2021) Ville Spatiale. Available http://www.yonafriedman. nl/?page_id=78. Accessed 28 Jan 2021 Gorman MJ (2005) Buckminster Fuller: designing for mobility. Skira, Milan, p 187 Ingenhoven (2021) Stuttgart Main Station: a railway station project of the 21st century. Available https://www.ingenhovenarchitects.com/ projects/more-projects/stuttgart-main-station/description. Accessed 21 Jan 2021 Jonas W (1962) Das Intrahaus - Vision einer Stadt [Intrahaus—vision of a city]. Origo-Verlag, Zurich Jonas W (2021) Biography. Available https://www.walterjonas.ch/ walter-jonas—english/biography/index.php. Accessed 22 Jan 2021 Kohn Petersen Fox (2021) KPF Completes Bundang Doosan Tower, a New Gateway to Seoul. Available https://www.kpf.com/current/ news/kpf-completes-bundang-doosan-tower-a-new-gateway-to-seoul. Accessed 18 May 2021 Kurokawa K (1977) Metabolism in Architecture. Available https:// monoskop.org/images/9/94/Kurokawa_Kisho_Metabolism_in_ Architecture_1977.pdf. Accessed 21 Jan 2021 Lin Z (2010) Kenzo Tange and the Metabolist movement: urban utopias of modern Japan. Routledge, London & New York Meissner I, Möller E (2005) “City in the Arctic”: a project study. In: Nerdinger W (ed) Frei Otto complete works: lightweight construction, natural design. Birkhäuser, Basel, pp 280–281 MoMA (2021) Joint Core System, project, Shinjuku, Tokyo, Japan (Elevation). Available https://www.moma.org/collection/works/815? artist_id=2837&page=1&sov_referrer=artist. Accessed 2 Feb 2021 Nettekoven T (2014) Tragstrukturen für visionäre Architekturkonzepte [supporting structures for visionary architectural concepts] Masters’ thesis, Technical University Berlin Novy J, Peters D (2012) Railway station mega-projects and the re-making of inner cities in Europe. Built Environ 38(1):128–145 Oldfield P (2012) Tall buildings and sustainability. Ph.D, thesis, University of Nottingham. Available http://eprints.nottingham. ac.uk/12700/1/PO_TallBuildingsAndSustainability_Abstract.pdf. Accessed 21 May 2021 Pawley M (1990) Buckminster Fuller. Trefoil, London, pp 149–151 Safdie Architects (2020) Raffles City Chongqing. Available https:// www.safdiearchitects.com/projects/raffles-city-chongqing. Accessed 26 Jun 2020 Safdie Architects (2021) ORCA mixed-use development + Park. Available https://www.safdiearchitects.com/projects/orca-mixed-usedevelopment-park. Accessed 18 Jun 2021 Sadler S (2005) Archigram: architecture without architecture. MIT Press, Cambridge, Massachusetts, USA, p 19 The World Bank (2021) Urban population (% of total population). Available https://data.worldbank.org/indicator/SP.URB.TOTL.IN. ZS. Accessed 5 Feb 2021 United Nations (2018a) Annual total population at mid-year (thousands). Department of Economic and Social Affairs, Population Division. World Urbanization Prospects: The 2018a Revision, custom data acquired via website. Available https://population.un. org/wup/DataQuery/. Accessed 5 Feb 2021 United Nations (2018b) Annual percentage of population at mid-year residing in urban areas. Department of Economic and Social Affairs, Population Division. World Urbanization Prospects: The 2018 Revision, custom data acquired via website. Available https:// population.un.org/wup/DataQuery/. Accessed 5 Feb 2021 Urfer AE (1999) Walter Jonas und seine Vision der Stadt [Walter Jonas and his vision of the city]. Available https://www.walterjonas.ch/ walter-jonas—deutsch/dokumentation/Urfer%20Alfred%201-111999.pdf. Accessed 17 Aug 2022

References Wood A (2010) Tall buildings: search for a new typology. Ph.D. thesis, University of Nottingham. Available http://eprints.nottingham. ac.uk/11486/1/00_AWPhD_TitleAbstractContentsNarrative.pdf. Accessed 21 May 2021 Woodman E (2015) Bosco Verticale by Stefano Boeri Architetti. Architect’s J 27 Feb 2015. Available https://www.architectsjournal.

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8

Timeline and Postscript

Abstract

The chapter presents a timeline of Michael Balz’s shell and urban design projects and research, and discusses the architect/engineer relationship in the design and attribution of shells. The potential for future of shell construction, on and off the planet, is evaluated.

8.1

Timeline

The timeline of Michael Balz’s shell and urban design projects and research, shown in Figs. 8.1, 8.2 and 8.3, reveals three distinct phases. In parallel with his more conventional architectural practice, the first 10 years, from 1965 to 1975, were primarily concentrated on his exploration of pneumatically form-found shells, mainly for use as ‘living’ shells—the Urschalen and ‘bio-segments’. This period included unbuilt designs for a house for a private client as well as a house and studio for Heinz and Maria Isler. An exception was the research into high-density urban living culminating in the competition entry together with Wilfried Beck-Erlang and Hans Lünz. A second phase, from 1976 to 1992, was marked by the realization of seven shells. With the exception of the Balz House, which was based on pneumatic form-finding methods, these were all of free form, based on the inverted hanging membrane technique. Over the same period, there were unbuilt designs for a high-profile architectural competition, Haus der Geschichte der Bundesrepublik Deutschland, Bonn, and speculative projects also of free form, based on his experimentation with hanging membranes. In the third phase, no shells have been constructed, but further proposals have been made for competitions— including for the German Pavilion for Expo’ 2000 in Hanover—and preliminary designs including for a number of international projects—most recently for the Shell of © Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7_8

Peace at the Heliopolis University, in Egypt (2016). In parallel, he has continued to elaborate his vision for future city living, for instance by collaborating in an exploration of their feasibility as megastructures.

8.2

Postscript

When we look back at the shell designs presented in this volume, we see that, unusually, it is the engineer, Heinz Isler, rather than the architect Michael Balz who has received the widest recognition for the realization of the free-form shells detailed in Chaps. 3 and 4. This is not unique. A similar situation also transpired with the attribution of the hyperbolic paraboloid shells constructed by the Spanish/Mexican, Félix Candela, where the contribution of the architects with whom he collaborated was largely unacknowledged until recently. This limited recognition of the project architect where there is a striking shell roof or building envelope supports the contention made earlier that in such buildings the structure becomes accepted as the principal and dominant architectural element. Hence, the name of the engineer of that structure, the thin shell, is often more strongly associated with the building than the name of its architect. There are, of course, exceptions, for instance, Eero Saarinen’s Kresge Auditorium, in Boston, USA (1954– 1955). In that case, it is the architect’s name that is primarily linked with the shell design and not the engineer, Ammann and Whitney (Joedicke 1963). Perhaps this was because the shell—an architecturally pure but structurally inefficient geometrically defined triangular segment of a sphere, which required stiffening edge beams—was predetermined by the architect. The engineer was left solely to make it stand, although it should be noted that there were difficulties with the stability of the structure at the time of construction, requiring permanent propping of the edge beam by structural glazing mullions. 199

8

Year

200

Built shells

Compeons

Unbuilt projects

1965

Timeline and Postscript

Research

Urschalen

1966 Evangelical Lutheran Church, Heilbronn

1967

Geborgenes Wohnen heute und morgen: neue Wohnformen — neue Baumethoden

1968

House for private client

1969

1970

‘Stugart 2000’

1971

Biosegment

1972

Isler house

1973 1974 1975 1976

Zuschauer halle,Theater unter den Kuppeln, Steen

1977

Naturtheater, Grötzingen, Aichtal

1978 Ballesaal (Ballet Salon), Steen 1979

Tropicana, Lucerne

Fig. 8.1 Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1965 to 1979 (Image credits and permissions (from top) are as noted in captions for Figs. 2.4, 5.7, 2.5, 2.11, 1.6, 2.15, 2.13, 3.5, 3.20, 3.23 and 6.1)

201

Year

8.2 Postscript

Built shells

1980

Balz house, Steen

Compeons

Unbuilt projects

Research

1981 1982

Badezentrum Sindelfingen (Thermal Baths), Böblingen

1983

1984 Haus der Geschichte der Bundesrepublick Deutschland, Bonn,

1985

Bösiger – Atelier and office building, Langenthal

1986 1987 1988

Musical-Saal (Musical Salon), Steen

1989 1990 1991 Entrance canopy, EuropaPark, in Rust

1992

Carport prototype developed with Willi Bösiger SA, Langenthal, Switzerland

Freizeit Park, Wallwitzhafen, Dessau 1993 1994

Thane, India: Modular dwelling units

Thane, India: Cosmo Ville, meditaon centre 1995 Exhibion space, EuropaPark, in Rust

Fig. 8.2 Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1980 to 1996 (Image credits and permissions (from top) are as noted in captions for Figs. 4.24, 5.15, 5.8, 6.4, 3.36, 3.42, 3.45, 6.13, 6.15, 6.19 and 3.43)

8

Year

202

Built shells

Compeons

Unbuilt projects

Timeline and Postscript

Research

Hegau Auto Rast Motorway Service Area, Engen 1997 German Pavilion, Expo’ 2000, Hanover 1998 1999 2000 2001 2002 2003 2004 2005

Cityscape Visions

2006 2007 Urban Space Agglomeraons

2008

2009 2010 2011 2012 Feasibility study of the mega-structures with Theresa Neekoven

2013

2014 2015

Skateboarding club 2016

Heliopolis University, Shell of Peace, Cairo, Egypt

2017

Street bar, Stugart

2018 2019 2020

Fig. 8.3 Timeline showing Michael Balz’s built projects, competition entries, unbuilt projects and research from 1997 to date (Image credits and permissions (from top) are as noted in captions for Figs. 5.25, 5.19, 7.12, 7.15, 7.13, 6.29 and 6.33)

8.3 Not Luxurious Expensive Dreams…

In the case of the Balz/Isler shells, the primary association of Heinz Isler’s name with the structures that they jointly realized conceivably occurred because he already had an established reputation as an innovative free-form shell-builder dating from the 1960s—a ‘structural artist’ as eminent Princeton University professor David Billington has described him (Billington 2003). Isler’s reputation was acquired well before Michael Balz had the opportunity to build his first shell, in Stetten in 1976, or the most spectacular in Grötzingen, in 1977–1978, which is also conceivably one of the most elegant of the free-form shells engineered by Isler. It should be documented that, until 2011, David Billington was unaware that the highly elegant form of the Grötzingen shell had initially been found by Michael Balz and not Isler. He was astonished to learn this directly from Michael Balz in conversation at a dinner held for the contributors to a special session in honour of Heinz Isler during the IASS Symposium, in London, in 2011—I was sitting next to David Billington at the time so can testify to his surprise! Michael Balz’s feelings about the attribution of the joint projects were conveyed to me in a letter he wrote to me dated 7 June 2001—twenty years ago—following his reading of my book on Heinz Isler and his shells (Chilton 2000). After commenting “[As] I see it this is the best documentation of Isler’s work which is existing”. He went on to say: Nevertheless let me comment some points: There are certain reasons why I don’t feel threatened by Heinz Isler. It is important to know that for all the projects we realized together the conceptual mainshape was developed by me. As architect it is my responsibility to decide where and when and how it is useful to work with this kind of shell- buildings. When using the well known laws for shell structures it is no problem to create such shapes. You know from lots of seminars where Heinz declares the shell generating methods. Of course you have to develop a special “shell-feeling”, if you want to avoid that the structural generating model “dictates” another shape as you had in your phantasy [imagination]. Very proud I was when the hanging model for Grötzingen differed in its curves only 2% to my original conceptional design I made in advance. Seen in principle in future countless visions of shells could be realised if our colleagues will start to understand how [these] methods are to [be applied]. May be it is not helping the further propagation of concrete shells for architects if they are told too loud as Isler - shells.

Their primary attribution as Isler shells is then contrasted with the different treatment of the tensile membrane structures such as those pioneered by Frei Otto. In the meantime it is usual as example that countless tent structures are arising in the whole world without to be told Frei Otto tents.

203 It is a fact of history and a consequence of evolution that progressive ideas like those of Heinz Isler or Frei Otto develop their own dynamic [life] separate from their discoverer.

He went on to talk specifically about his own house, of which he is clearly and deservedly extremely proud, saying: Another fact should be mentioned: the reason why we built the Balz - shell house was to prove, that organic shapes of living are more natural and comfortable for human users than normal ort [h]ogonal and cubic forms of housing. I am very proud and happy, that I could convince the administration over our mayor that on this special site only organic shapes are allowed. This has been fixed as masterplan in the building laws of our town. Therefore design of this house is not the result of adaptation of a dictated shell-shape. On the contrary: the shell shape has been developed as optimal surrounding for human living habits. My family our visitors and I are feeling that since more than 20 years.

It is apparent from the built and unbuilt projects, and the diverse competition entries that the primary architectural inspiration for the projects on which they collaborated came from Michael Balz. Heinz Isler applied his great skill and experience as engineer and shell designer to confirm the structural soundness of the free-forms and advise on their construction. It was Michael Balz who experimented with inflated balloons to determine the form of his own house and with hanging chain and membrane models to achieve a variety of free-form shells. Sadly, the majority of those inspiring forms, highlighted in Chaps. 5 and 6, have not yet been executed. If they had been, we might now be talking about Balz shells…

8.3

Not Luxurious Expensive Dreams…

Michael Balz has recently commented “…shell buildings are not luxurious expensive dreams…”. He is confident that the shells he constructed between 1976 and 1992, within the constraints of the high wage German economy, were achieved at prices comparable to more conventionally shaped reinforced concrete buildings for clients with limited budgets (Balz 2021). Recently, in a paper presented at the IASS Symposium 2021, in a session dedicated to twenty-first century fabrication and construction of shells, I posed the question “What future for reinforced concrete shell construction in the UK in the twenty-first century?” (Chilton 2021). This is a question that could equally be applied to most countries. My paper was prompted by the construction of what I believe to be the first long-span concrete shell to be built in the UK after a gap of almost 25 years, for the First Light Pavilion, Jodrell Bank, near Macclesfield (architects,

204

8

Hassell Studio: engineers Atelier One), since opened in 2022. As far as I’m aware, the only other medium- or long-span architectural shells built in the UK since the early 1970s were nine tennis halls (1987) and a swimming pool (1991) in Norwich—the only examples of Isler shells in the UK designed in collaboration with architect Tony Copeland —and the American Air Museum, Duxford, near Cambridge (architect Foster + Partners, engineers Arup). It is pertinent to note that the Norwich shells were built at approximately the same time as Michael Balz was collaborating with Heinz Isler on the design of an atelier and office building in Langenthal for Willi Bösiger AG (1986), and when they were constructing their final joint projects, the Musical-Saal in Stetten (1988), entrance canopy in Rust (1992) and the BBI prototype carport (1992). The construction of the First Light Pavilion, a domed shell spanning up to 50 m, represents a renewed interest in shell building, at least in the UK. The shell was completed in one continuous pour—381 m3 of concrete was placed in 10 h with a team of 59 workers (Museums + Heritage Advisor 2020). Although it could be argued that this is a very specific application—the building is set almost entirely into the ground and the shell forms an earth-covered mound in the landscape (Hassell Studio 2021a)—it has validated that a reinforced concrete shell can be built competitively against alternative materials and economically under the financial constraints of public funders, which include the National Lottery Heritage Fund and the UK Government Department of Culture, Media and Sport. This suggests, as concluded in my recent paper, that architectural fashion and lack of promoters may be the principal constraint to more extensive use of reinforced concrete shells. Education is the key. Architects and building designers need to be made aware of the undoubted benefits of shells, and this will only come if they are exposed to high quality exemplars such as Michael Balz’s shell designs—both built and unbuilt—highlighted in this volume. It is hoped that these will inspire a new generation of architects and engineers to explore the infinite possibilities of organic- and free-form shells limited only by the bounds of their imagination.

8.4

There Are No Limits

The potential for shell construction is not restricted to Earth. As mentioned in Sect. 2.6, recent experiments with 3D printing of housing have opened up the possibility of shaping living shells directly using locally found soil materials without the use of formwork (Mario Cucinella Architects 2021; WASP 2021). This technology removes

Timeline and Postscript

commonly acknowledged constraints of shell construction— that complex, often single-use, formwork is required on which to cast double-curved forms and the high cost of labour for their crafting. Consequently, the potential for application of this technology on other worlds has also been explored, as suitable soil materials would most likely be available on or near their surface. No complex mining operations would be required for minerals, and the technique would be applicable even on worlds where there is no vegetation to construct the equivalent of timber structures. From 2014 to 2019, the United States National Aeronautics and Space Administration ran a design competition for a 3D-printed habitat suitable for construction on the Moon, Mars or even further afield (National Aeronautics and Space Administration 2021). Several of the entries proposed some type of organically shaped 3D-printed shell. These are clearly very appropriate, as a shell form can encompass a large floor area using the minimum volume of hard-won material and minimize the enclosed volume where the environment needs to be controlled for human habitation. Coincidentally, one of the top-ten shortlisted entries was a design by Hassell Studio, architects for the First Light Pavilion, in collaboration with engineers Eckersley O’Callaghan, which was to be built by autonomous robots using material won from the Mars surface (Hassell Studio 2021b). That the National Aeronautics and Space Administration, at the forefront of space exploration and technological innovation, are open to the notion of constructing shells on other worlds demonstrates that there is a future for architectural shell construction both here on Earth and throughout the universe!

References Balz M (2021) Personal communication 18 Aug 2021 Billington D (2003) Heinz Isler: structural art in thin-shell concrete. In: The art of structural design: a Swiss legacy. Princeton University Art Museum/Yale University Press, pp 128–162 Chilton JC (2000) Heinz Isler: the engineer’s contribution to contemporary architecture. Thomas Telford Ltd., London Chilton J (2021) What future for reinforced concrete shell construction in the UK in the 21st century? In: Behnejad SA, Parke GAR, Samavati OA (eds) Inspiring the next generation: proceedings of the IASS annual symposium 2020/21 and 7th international conference on spatial structures, Guildford, UK, August 2021 Hassell Studio (2021a) First Light Pavilion Visitor’s Centre. Available https://www.hassellstudio.com/project/first-light-pavilion-visitorscentre. Accessed 21 Sep 2021 Hassell Studio (2021b) NASA 3D printed habitat challenge. Available https://www.hassellstudio.com/project/nasa-3d-printed-habitatchallenge. Accessed 21 Sep 2021 Joedicke J (1963) Shell architecture, Reinhold, pp 126–127

References Mario Cucinella Architects (2021) TECLA—technology and Clay. Available https://www.mcarchitects.it/tecla-2. Accessed 10 May 2021 Museums + Heritage Advisor (2020) Dome roof completed as construction of First Light Pavilion at Jodrell Bank advances, 29th October 2020. Available https://advisor.museumsandheritage. com/news/dome-roof-completed-construction-first-light-pavilionjodrell-bank-advances/. Accessed 6 Apr 2021

205 National Aeronautics and Space Administration (2021) 3D-printed habitat challenge. Available https://www.nasa.gov/directorates/ spacetech/centennial_challenges/3DPHab/index.html. Accessed 21 Sep 2021 WASP (2021) TECLA. Available https://www.3dwasp.com/en/3dprinted-house-tecla/. Accessed 10 May 2021

Additional Information

Publications by Michael Balz Beck-Erlang W, Lünz H, Balz M (1970) Grand Prix International d‘Urbanisme et d’Architecture, 1970 m-d Konradin-Verag D–70771 Leinfelden-Echterdingen, Germany Balz M, Isler H (1990) Architectional aspects of organic forms. In: Proceeding of the IASS symposium, Dresden Balz M (1996) Organic shell architecture for dwelling as modular structures and for public amenities. In: Proceedings of the IASS symposium Beijing China Balz M (2000) Phantasy in space: on human feeling between the shapes of the world and how to look on natural structures. In: Gerrit JM (ed) Bridge between civil engineering and architecture, Proceedings of 4th international colloquium on structural morphology, 17–19 Aug 2000, Delft, The Netherlands pp 7–14 Balz, M (2003) Use of space above the towns. In: Proceedings of the IASS–ACPS symposium, Taipei, Taiwan Balz M, Böhm J (2004) Generating shell models and their realization by photogrammetric measurement. In: Motro R (ed) Shell and spatial structures from models to realization, Proceedings of IASS symposium 2004, Montpellier, France, Extended abstract, pp 290– 291; full paper TP119 on CD-ROM Balz M (2005) Chances of natural design in the new century. In: Mihailescu M, Mircea C (eds) Theory, technique, valuation, maintenance, proceedings of the IASS symposium 2005, Bucharest, Romania, pp 797–804 Balz, M (2006) How will look the Crown of Megatown?. In: New Olympics: new shell and spatial structures, Proceedings of IASS–ACPS symposium, Beijing, China, Extended abstract pp 526–527; full paper on CD-ROM

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7

Balz, M, Dürr H (2007) Urban space structures. In: Shell and spatial structures: structural architecture—towards the future looking to the past, Proceedings of IASS symposium 2007, Venice, Italy, Extended abstract pp 45–46, full paper on CD-ROM Balz, M, Dürr H (2008) Urban space agglomerations. In: Oliva Salinas JG (ed) New materials and technologies, new designs and innovations—a sustainable approach to architectural and structural design, Proceedings of the IASS–SLTE symposium 2008, Acapulco, Mexico, Extended abstract pp 61–62, full paper on CD-ROM Balz, M (2011a) Urban space conceptions. Paper presented at the 3rd conference on spatial structures, University of Tehran, Iran Balz, M (2011b) Working with Heinz Isler. In: Taller, longer, lighter— meeting growing demand with limited resources, 35th annual symposium of IABSE/52nd annual symposium of IASS/6th international conference on space structures, London, United Kingdom, September 2011b, Abstract p 50, Paper 683, p 8 on CD-ROM Balz, M, (2017) Beyond the cube—the spirit of Frei Otto. Presented at: Interfaces: architecture, engineering, science, annual meeting of the international association of shell & spatial structures (IASS), HafenCity University, Hamburg, 25–27 Sept 2017. Paper 10818, p 19

Website Balz M (2021) Dipl.-Ing. SBS, Freier Architekt. Available via: http:// www.michael-balz.de/index.htm. Accessed 30 June 2021Publications about Michael Balz’s shells Balz M (2021) Structurae: international database and gallery of structures. Available via: https://structurae.net/en/persons/michaelbalz. Accessed 25 June 2021

207

Index

A Abouleish, Ibrahim, 157 Airform houses, 16, 27 Akashi Kaikyō Bridge, 181 Alexandra Road Estate, London Borough of Camden, 95 Allgemeine Orts Krankenkasse (AOK), 4 American Air Museum, Duxford, near Cambridge, UK, 204 Ammann and Whitney, 199 Anthroposophy, 13, 157 Archigram, 176, 191 Architektur Büro Schaal, Heilbronn, 4 Arup, 192, 204 Atelier One, 204 B Baden-Württemberg, 71, 83, 99, 100, 127 Baden-Württemberg Chamber of Architects, 4 Badezentrum Sindelfingen, BÎblingen, 121 Bahnhof Dessau-Wallwitzhafen, 143 Ballettsaal (Ballet Salon), 11, 51, 60, 135 Balz, Angelika, 86, 91 Balz, Doris, 1, 13 Balz, Ernst, 1, 3 Balz, Eva, 2, 85 Balz House, 21, 36, 37, 39, 68, 83–89, 91, 92, 95, 96, 98–100, 102, 104–106, 141, 147, 178, 199 Balz, Johannes, 86, 116 Balz, Markus, 60, 74, 86, 98, 127 Bauer + Strässle, Stuttgart, 4 BAYPREN®, 16 BBI High Tech Carport, 64 Beck-Erlang, Wilfried, 6, 175, 176, 199 Billington, David, 42, 135, 203 Bio-segment, 13, 31–35, 147, 154 Bosco Verticale, 191 Bösiger, Heinz, 127 Bösiger, Willi SA, 37, 60, 64, 66, 79 Bridge structures, 181, 192 Brown, Neave, 96 Bubble shells, 16, 18, 49, 137, 141 Buckling, 41, 47, 48, 52 Bundang Doosan Tower, Seoul, South Korea, 195 Burgdorf, Switzerland, 16, 27, 29, 30, 37 Busso von Busse, Dipl.-Ing. Hans, 4

© Springer Nature Switzerland AG 2023 J. Chilton, Michael Balz, https://doi.org/10.1007/978-3-031-19264-7

C Candela, FÅlix, 37, 107, 108, 199 Carport, 37, 64, 66, 79, 80, 204 Catenary, catenaries, 5, 42, 125 Chambered nautilus, Nautilus pompilius, 14 City in the Air/ Clusters in the Air, 175 Cook, Peter, 176 Copeland, Tony, 204 Cosmo Ville, 147, 153–156 Couëlle, Jacques, 27 Crystal Skybridge, 195 D Deitingen Süd, 107, 127, 135 De la Mora, Enrique, 107 Dessau, 141, 147 Dry-Bulb Air Temperature (DBT), 95 Durability, 46, 96, 192 Dwelling trees, 6, 8 E Edge profiles, 52, 62, 164 Embodied energy, 20, 102 Energy capture and heating system, 92 Entrance canopy/canopies, 37, 59, 60, 74–76, 204 Esquillan, Nicolas, 125 Europa Park, Rust, 11, 37, 59, 60, 147 Evangelical Lutheran, 11, 107–110, 129 F Færge Cafeen, Copenhagen, 11 Federal State Baden-Württemberg, 83, 127 1st International Colloquium on Pneumatic Structures, 5, 16 First Light Pavilion, Jodrell Bank, near Macclesfield, UK, 203 Flower House, 147, 151, 152 Foster + Partners, 204 Freizeit Park (Leisure Park), 141, 143 Friedman, Yona, 175 Fritz, Johannes, 112, 116, 118, 119 Fuller, Richard Buckminster, 176, 192

209

210 G Gabel, Dr.-Ing. Rudolf, 4 Gaudí, Antoni, 13 Geborgenes Wohnen heute und morgen: neue Wohnformen — neue Baumethoden (Secure Living Today and Tomorrow: New Forms of Housing — New Construction Methods), 18, 19, 83 German Democratic Republic (GDR), 134, 141 German National Museum of Contemporary History, Bonn, 107, 108, 115, 117–120 German Pavilion, Expo‘ 2000, Hanover, 107, 121, 126–30, 199 German Pavilion, Expo ’67, Montreal, 4 Gerstel, Professor Wilhelm, 1 Glazed façade(s), 48, 51, 52, 85, 92, 121, 127, 137, 157, 167 Goetheanum, 13 Goff, Bruce, 13 Graf, Reiner, 6, 7 Grand Prix International d’Urbanisme et d’Architecture, 176 Grötzingen, Aichtal, 11, 37, 41, 135 Groupe International d'Architecture Prospective (GIAP), 175 Gunite, 16 Gutbrod, Rolf, 4 H Habitat, Expo’67, Montréal, Québec, Canada, 23 Hassell Studio, 204 Haus der Geschichte der Bundesrepublik Deutschland, Bonn, 108 Heat pump, 94, 96 Hegau Auto Rast, Engen, 127 Heilbronn, 1, 4, 11, 107–110, 129 Heinz Isler Archive, Institut für Geschichte und Theorie der Architektur (gta), Eidgenössische Technische Hochschule (ETH) Zürich (Institute for the History and Theory of Architecture, Swiss Federal Institute of Technology), 54, 139 Heliopolis University, Cairo, 135, 157 Hochschule für Technik [University of Technology], Stuttgart, 4 House of One, 157, 164 Hyperbolic paraboloid or 'hypar', 107 I IASS Advisory Board, 12 IASS Tsuboi Award, 11, 12 Institute for Lightweight Structures and Conceptual Design (ILEK), 4, 5, 116 Institute for Lightweight Structures, IL, 4 Institut für Leichte Flächentragwerke, 4 International Association for Shell and Spatial Structures (IASS), 1, 5, 11, 12, 40, 85, 203 Intrapolis, 175 Inverted hanging membrane, 40, 51, 107, 199 Isler ‘Bubble System AG’, 33 Isler, Heinz, 1, 5, 11, 13, 16, 18, 19, 27, 33, 37, 40–42, 47, 49, 51–53, 60–63, 66, 83, 87, 107, 108, 112, 113, 119, 127, 134, 135, 137, 139, 140, 143, 147, 166, 172, 173, 199, 203, 204 Isler, Maria, 11, 27, 29–31, 37, 83, 135, 199 Isozaki, Arata, 175

Index J Jonas, Walter, 175 K Kahn, Louis, 181 Kikutake, Kiyonori, 175 Koch und Mayer, 1 Kresge Auditorium, Boston, USA, 199 Kurokawa, Kiyonori (Kisho), 175 L Lady’s-slipper orchid, Cypripedium calceolus, 14 Landesamt für Denkmalpflege (State Office for the Preservation of Historical Monuments), 99 Latex, 137, 142 Leinfelden-Echterdingen, 8, 11, 83 Lenticular, 121, 124, 125, 135, 147 Living shells, 20, 24, 27, 28, 33–35, 108, 135, 178, 204 Lloyd Wright, Frank, 13, 108 Lopez Carmona, Fernando, 107 Lünz, Hans, 6, 175, 176, 199 Lyssachschachen, 18, 27, 29–31, 139 M Maki, Fumihiko, 175 Makowitz, Imre, 13 Mario Cucinella Architects, 36, 204 Mean Radiant Temperature (MRT), 95 Mega-structures, 191, 192 Meid, Dipl.-Ing. Max, 4 Metabolism, 175 Mir space station, 60, 77, 78 Modular, 11, 13, 31, 33, 61, 81, 147, 152, 172, 179, 182–184, 186–188, 195 Musical-Saal (Music Salon), 11, 37, 57, 143 N Naturtheater, Grötzingen, Aichtal, 41, 135 Neff, Wallace, 16, 27, 33 O Operational energy, 20, 101, 102, 172 ORCA, Toronto, Ontario, 196 Organic architecture, 4, 13, 105, 157, 178 Organic Photovoltaic (OPV) cells, 98 Otaka, Masato, 175 Otto, Professor Frei, 4 P Precious wentletrap, Epitonium scalare, 14 Prefabricated, 13, 16, 31, 64, 66, 79, 80, 147, 152, 178, 179 Prix International d'Architecture, 6, 176 Prototype shells, 13, 15, 18

Index Q Quarmby, Arthur, 24 R Raffles City Chongqing complex, China, 195 River Emme, 18 Romeik, Dipl.-Ing. Helmut, 4 Ruge, Siegfried, 127 S Saarinen, Eero, 199 Safdie, Moshe, 23, 195 Scharoun, Hans, 13 Scorer, Sam, 108 SEKEM, 11, 157, 164, 165 Shell of Peace, 11, 135, 157–165, 199 Sicli SA, Geneva, 107, 113, 119, 135 Skateboarding, 166–169 Skybridges, 191, 195, 196 Solar photovoltaic panels, 96 Space station Mir, 60, 77, 78 Spatial city, 192, 194 Sprayed concrete, 60, 64, 67, 87 Staatsbauschule [State Construction School], Stuttgart, 4 Stefano Boeri Architetti, 191 Steiner, Rudolf, 13, 157 Stetten auf den Fildern, 37, 38, 60, 83, 85 Stohrer, Professor Paul, 4 Street bar, Stuttgart, 167, 170, 171 Structural artist, 41, 135, 203 Structural Morphology Group (SMG), 11, 12 Structural performance, 47 Stuttgart 2000, 6, 8, 11, 175–177, 196 Stuttgart 21, 176 Surface patina, 49, 57, 58 T Tange, Kenzo, 108, 192 Technische Hochschule, Stuttgart (Technical High School, Stuttgart), 4

211 TECLA house, Massa Lombarda, Italy, 36 Thane, Mumbai, India, 147, 151–153 Theater unter den Kuppeln, 11, 37, 40–42, 51, 60, 64–69, 71–73, 85 Thermal baths, 121, 122, 147 Thermal comfort, 95 Thermoformed insulated shells, 81 3D printing, 33, 204 Timeline, 199–202 Torkret, 16 Torroja, Eduardo, 11 Tropicana, Lucerne, 135, 136, 138, 147 Tsuboi, Kazuko, 11 Tsuboi, Professor Yoshikatsu, 11 Tsuboi Yoshiaki, 11 Tyng, Anne Griswold, 181 U Underhill, Holme, West Yorkshire, 24 United States National Aeronautics and Space Administration, 204 Urban space structures, 175, 176, 178, 181, 195, 196 Urschalen, 13, 15, 16, 18, 23, 108, 199 V Ville Spatiale, 175 Von Goethe, Johann Wolfgang, 157 W Wallwitzhafen, Dessau, 148–150 Willi Bösiger AG, 33, 135, 137, 139–147, 172, 173, 204 Wood–wool panels, 40, 164 World population, 11, 179, 195 Z Zuschauer halle (Auditorium), 11, 37, 66