I was once at a showroom with my husband trying to choose tiles for our bathroom. At 6 p.m. precisely, the salesman looked at his watch, put his pen in his breast pocket, told us politely but decisively that it was closing time, turned and left the building, leaving us – astonished – behind. The work of a researcher is never finished in this way, but the moment when a manuscript is sent out for publishing comes close. At such a time, it is appropriate to thank the many people who have contributed to the research.

First and foremost, I am greatly indebted to my promoters Ernst ten Heuvelhof and Jitske de Jong for their never-ending trust, patience and support, and for their efficient and effective supervision. You have succeeded in teaching at a conceptual level, a quality that is reserved for true professors. In addition, I want to thank my colleagues at the Faculty of Technology, Policy and Management of Delft University of Technology. You form an inspiring, challenging, interdisciplinary and dynamic environment of reflective practitioners and academics. In our joint teaching, research and consultancy, you form an endless source of intellectual capital. My direct colleagues at the Policy, Organisation, Law and Gaming section were always there for critical reflection and debate, and made sure I did not lose sight of my roots in public administration. In particular, I want to thank Joop Koppenjan and Igor Mayor for their cooperation and valuable feedback; Martin de Jong for bringing evolutionary theory to my attention; Hans de Bruijn, for giving me room to finish this book; and Hilda Verwest for her practical advice and mental support.

A second group of people that I want to thank are all those who have been involved in the case studies reported in this book, as supervisor, commissioner, reviewer, informant, or respondent. Without your valuable time and input, this research could not have been done. Especially the people who reviewed draft case study chapters deserve mentioning here: Peter Vermij (Waterdienst), Jules Wilhelmus (Stichting Duurzaam Bouw Metaal), Peter van Oppen (SBR), Rogier Goes (NVTB), Dick Tommel (former state secretary), Kees Vriesman (Programme bureau Town-Countryside Randstad, former director-general at the Ministry of Housing, Spatial Planning and the Environment), Rianne Zandee and Douwe Tiemersma (Stichting Natuur en Milieu), and professor Andreas Faludi (Delft University of Technology). I appreciate your corrections, work and help, and enjoyed our debates. You gave me the background information needed to understand the wider context of decision-making at the time.

Parts of the case studies have been conducted in collaboration with other reseachers; I learned a lot from working with you. Joop Koppenjan and Erik-Hans Klijn: in our exploration of the zinc case, you further introduced me to the nitty-gritty of policy networks. Members of the DIOC team: you showed me the design and engineering perspectives of sustainable built environments and with some of you I dived into the National Packages for Sustainable Building. Ernst ten Heuvelhof and Hans de Bruijn: doing research for the contours case with you gave me a kickstart at your group in Delft and showed me the added value of applied research by academics. Igor Mayer, Pieter Bots and Robin Seijdel and his PRC colleagues: together we took up the challenge to develop the DUBES Game, a true interdisciplinary venture in which you let me discover the value of modelling, simulation and gaming.

A third group of people I want to thank are all those people with whom I collaborated in interdisciplinary projects about sustainable built environments and who directly or indirectly contributed to this thesis. The thesis has its origins in DIOC The Ecological City, the Delft Interfaculty Research Centre. Guided by professor Kees Duijvestein, professor Hugo Priemus and the late professor Charles Hendriks, the committed teamwork in the centre formed an excellent basis for multidisciplinary and interdisciplinary research, which was prolonged in the Delft Centre for Sustainable Urban Areas under the supervision of professor Peter Boelhouwer and Marjolein Spaans. This collaboration has also laid the foundation for the Sustainability in the Built Environment course for the MSc. in Industrial Ecology and for an upcoming textbook, which is a joint production by the Faculties of TPM, Architecture, Civil Engineering and Geosciences and OTB Research Institute for Housing, Urban and Mobility Studies. Then there were projects with external partners, academics, consultants and practitioners. I enjoyed working with TNO on several projects, of which the Sureuro (Sustainable Refurbishment in Europe) project, managed by Karel Dekker, was a very special experience. Delft Cluster formed another inspiring research environment; they deserve special thanks for providing financial support for the delivery of this thesis.

The fourth and final group of people that I explicitly want to acknowledge here are my friends and family: my friends from the Zijstraten, AOD, tennis/ volleyball Rijnsburgerweg, the South Africa team, the Provros, and Zandvoort, who were always there to support me, Thurstan for the last-minute language checks, and Titia and Eske for going all the way with me by accepting the questionable honour of being my ‘paranimfs’. I would also like to thank my in-laws for their encouragement, and my parents and sister who have done more than their fair share of baby-sitting in support of this thesis. And finally, of course, my thanks go to Marco and my children, for spending many weekends in playgrounds, museums and theatres in order to give me some quiet working hours.