The International Building Performance Simulation Association (IBPSA) was founded to advance and promote the science of building performance simulation in order to improve the design, construction, operation and maintenance of new and existing buildings worldwide. IBPSA recognises the complexity of building performance and the many factors that influence this. This book addresses these issues in detail, unpacking the meaning of building performance analysis by considering its history and current practices. In doing so, it leads the reader to an appreciation of the fundamental importance of building performance analysis and the role it plays at all stages of the life cycle of a building, leading to an emergent theory of building performance analysis in Chapter 11.

Along this journey, the book mobilises an extensive quantity of relevant literature on this broad subject, making it an invaluable resource for students at all levels. Each chapter concludes with a list of activities that not only serves as a summary of the material covered but also provides an excellent basis from which to develop student projects and assessments.

The book provides a broad range of insights, food for thought and suggestions for how to approach your own building performance analysis. It is hoped that the book will go some way to elucidating the topic, equipping graduates with the knowledge and awareness required to specify, design, procure and operate high performance buildings that deliver high quality indoor environments and low energy consumption.

IBPSA is grateful to Professor De Wilde for the many hours he has devoted to bringing this book to fruition and commends it to anyone pursing a detailed knowledge of building performance analysis and its allied disciplines.

The International Building Performance Simulation Association (IBPSA) makes every effort to ensure the accuracy of all the information contained in publications that it endorses. However, IBPSA, our agents and our licensors make no representations or warranties whatsoever as to the accuracy, completeness or suitability for any purpose of the content. Any opinions or views expressed in this publication are the opinions and views of the authors and are not the views of IBPSA. The accuracy of the content should not be relied upon and should be independently verified with primary sources of information. IBPSA shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of this content.

Ever since I was a young researcher in building simulation at TU Delft, I have been intrigued by the prospect of being able to support rational dialogues in building design projects, in particular to express unambiguously how we want buildings to behave or what goals we want to achieve with them. This inevitably invites the hypothesis that design can be managed as a purely rational fulfilment process in which clients precisely define their expectations (as requirements) and designers verify their creatively generated proposals (as fulfilment) against these expectations. It doesn’t take much to realise that this can only be realised by introducing a set of objectively quantifiable measures, agreed upon by both parties. When expectations are not met, design adaptations or relaxation of client requirements could be negotiated. For many years I have taught a graduate course on this subject that I loosely labelled as ‘performance‐based design’. It was meant to whet the appetite of PhD students that walked in with vague notions about the next generation of building design methods and frameworks to support them. The course examined the literature in an attempt to cement the foundation of the central concepts such as performance, measurement and quantification. Then I showed how their operationalisation requires the development of a plausible worldview of buildings in which their system specification is expressed at increasing levels of resolution and as steps in an evolving design process.

Pieter de Wilde was one of the PhD students who was brave enough to voluntarily enrol in the course. He was looking for answers to his fundamental thesis research, only to find out that the course stopped far short of offering a methodology that could be mapped onto real‐world design projects without some vigorous arm waving. For one there were still many missing pieces that could only be ‘covered’ by fuzzy connections. But above all, a unifying theory that gives building performance analysis a precise meaning in every application setting was and still is missing. The lack of a rigorous definition of generic tasks in building projects is one of the prime reasons why this situation persists. In the course I repeatedly stressed that the lack of a textbook that offers all relevant concepts and underlying ideas in one place is felt as another obstacle to attract the recognition the domain deserves. Some 15 years later, during a long drive through the English countryside, Pieter offered the idea to do something about this, and 3 years later, this resulted in the monograph that is in front of you. The road travelled in these 3 years has been as curvy and challenging as the drive through rural Devon, trying to avoid the sharp edges of the stone hedgerows and slowing down enough at blind corners. Fortunately Pieter’s skills at the steering wheel kept me safe, and his skills at the keyboard proved to be an equal match for all narrow theories and blinding misconceptions that lay ahead.

I am very happy that this book got written. For one, it brings together the extensive body of work that has gone before, thus providing the first coherent account of the state of our knowledge in building performance, from fundamental concepts to operational measures, followed by their quantification in real‐life cases. In organising the book along these three parts, the author has succeeded in taking the reader from a generic basis to operationalisation that gets ever more specific towards the later chapters. This approach is the perfect reflection of the fact that although the basis of performance concepts is generic, their application demands creative thinking and will always be case specific. The link between the two is realised by a broadening palette of multi‐aspect building simulation tools of which the book provides a good overview. The central theme of the book is in the experimental and simulation based analysis of building performance, elegantly wedged between the fundamental concepts of performance and their operationalisation in specific case settings.

Students, developers and scholars in the field of building performance simulation, design management, performance‐based design and rationalisation of building design will find this book useful. And although the ultimate solution for the purely rational design dialogue that I have been chasing remains elusive, this book provides a new and essential stepping stone towards it.

Building performance is a concept that is used throughout industry, government and academia. It plays an important role in the design of new buildings, the management and refurbishment of the existing stock and decisions about the built environment in general. Yet there is no clear definition of building performance or unifying theory on building performance analysis available in the literature.

This book is an attempt to fill this void and to answer the following key questions:

1. What is building performance?
2. How can building performance be measured and analysed?
3. How does the analysis of building performance guide the improvement of buildings?
4. What can the building domain learn from the way performance is handled in other disciplines?

In order to answer these questions, the book brings together the existent body of knowledge on the subject. It combines findings from a large number of publications on aspects of building performance that all contribute in different ways. The book tries to unify this previous work, establishing a range of observations that underpin an emergent theory of building performance and building performance analysis. At the same time, the material makes it clear that there still is significant work to do: the theory does not reach beyond a conceptual framework. Operational building performance analysis still requires deep expertise by those carrying out the analysis, and existing tools and instruments only support part of the work. A design methodology that truly ensures performance of a building according to predefined criteria still remains to be developed.

In providing a working definition and emergent theory of building performance analysis, the book caters primarily to the building science community, both from industry and academia. It aims to support the many efforts to build better buildings, run more efficient design processes and develop new tools and instruments. The book will benefit senior undergraduate and graduate students, scholars as well as professionals in industry, business and government. Students engaging with this material will typically be those that are taking a course at MSc level in one of the many directions in architecture and building engineering, such as building performance modelling, environmental building design and engineering, high performance buildings, intelligent/healthy/low‐carbon/sustainable buildings, building science and technology or building services engineering. While the text is intended to be self‐contained, it will be helpful if such readers have developed a solid appreciation of building technology and the construction process, as well as building science. It will also be beneficial if students have been introduced to building simulation and physical experimentation. Research students and academics will have their own specific research interests but will benefit from a unified theory upon which to base their efforts. Extensive references are provided so that these readers can connect to the underlying foundations. It is hoped that professionals can use this material to reflect on the current way of handling performance in the field and that they will help to implement some of the ideas of this book in practice.

The book is structured in three parts. Part I provides a theoretical foundation for building performance. Part II deals with operational performance analysis, providing a conceptual frame that shows what deliberations and decisions are required to carry out an analysis and what tools and methods are available to help. Part III discusses how this analysis can impact on building practice. The book closes with an epilogue that presents an emerging theory of building performance analysis. A study of the complete book allows the reader to follow the underlying thought process and how it connects the many contributions that already have been made to aspects of the field. However, readers who prefer to start with getting an understanding of the emergent theory, or want to test their own ideas against this, may start by reading the final chapter and then explore the underpinning material as required. Non‐linear readers may start at any chapter of interest. The main chapters all include a case study that demonstrates the complexity of building performance analysis in real practice; these cases are intended as challenge for readers to reflect on applicability of the emergent theory. Each chapter also includes six activities that encourage engagement with the material; these have been designed to be ‘real‐world’ problems without a right model answer but instead should provide a basis for deep discussion within groups or teams. Key references are included in the references at the end of each chapter; a complete list and secondary references are provided at the end of the text.

This book is written to encourage dialogue about an emergent theory of building performance and its analysis. A website is maintained at www.bldg‐perf.org to support communication on the subject.

This book is the result of more than twenty years of research in and around the area of building performance. In these two decades, many people have influenced my thinking about the subject. By necessity, not all of them can be listed, so these acknowledgements only name those who had a pivotal role in the emergence of this work.

I was introduced to building performance simulation during my studies at the TU Delft, starting with my graduate work in 1994 and continuing on this subject during my PhD project. My supervisor at that time, Marinus van der Voorden, thus laid the foundations of this effort. During my time as postdoc on the Design Analysis Integration (DAI) Initiative at GeorgiaTech, Fried Augenbroe provided deeper insights and guidance. My involvement in DAI also established invaluable connections with Cheol‐Soo Park, Ruchi Choudhary, Ardeshir Mahdavi and Ali Malkawi, who influenced my subsequent career. My years with Dick van Dijk and the other colleagues at TNO Building and Construction Research had a stronger emphasis on industrial application and physical experimentation, giving me a more balanced perspective on the interaction between academia and practice. At the University of Plymouth, Steve Goodhew and colleagues expanded my view in a yet another direction, emphasizing the actual construction process and importance of the existing building stock. Yaqub Rafiq introduced me to genetic algorithms. Derek Prickett became a trusted voice on the practical aspects of building services engineering. Wei Tian, postdoc on my EPSRC project on the management of the impact of climate change on building performance, introduced me to parallel computing and the handling of large search spaces and the application of sensitivity analysis to make sense of the results. Darren Pearson and his colleagues at C3Resources gave me an appreciation of the worlds of monitoring and targeting, automated meter reading and measurements and verification; Carlos Martinez‐Ortiz, the KTP associate on our joint project, introduced me to machine learning approaches. Sabine Pahl and other colleagues in the EPSRC eViz project not only provided me with a deeper understanding of the role of occupant behaviour in building performance but also made me realise that building performance analysis is a separate discipline that needs its own voice. My Royal Academy of Engineering fellowship brought me back to GeorgiaTech in order to learn more about uncertainty analysis; the discussions with Yuming Sun on the energy performance gap also helped shape my thinking. My work at Plymouth with my postdocs and students, notably Rory Jones, Shen Wei, Jim Carfrae, Emma Heffernan, Matthew Fox, Helen Garmston, Alberto Beltrami, Tatiana Alves, João Ulrich de Alencastro and Omar Al‐Hafith, helped me see some of the complexities of building performance and advance my thoughts on the subject. The colleagues within the International Building Performance Simulation Association (IBPSA) have provided an excellent frame of reference ever since my first IBPSA conference in 1997; over the years some of them like Chip Barnaby, Malcolm Cook, Dejan Mumovic and Neveen Hamza have become trusted friends and references for my efforts. The same goes for the colleagues such as Ian Smith, André Borrmann, Timo Hartmann and Georg Suter that are active within the European Group for Intelligent in Computing in Engineering (EG‐ICE) and for those active within the Chartered Institution of Building Services Engineers (CIBSE).

The specific idea to write this book on the subject of building performance analysis crystallised in October 2014 during a visit of my long‐term mentor Fried Augenbroe, on the basis of a casual remark as we were driving to Bristol airport. Further momentum was gained a month later from a discussion with Ruchi Choudhary about real contributions to the field of building simulation during a visit to Cambridge University, leading to the actual start on this manuscript. My special thanks to both of them for setting me off on this journey of discovery. Thanks are also due for many people who provided input on elements of the text and helped with images, such as Joe Clarke, Wim Gielingh, Nighat Johnson‐Amin, Gayle Mault and Ioannis Rizos.

Achieving the current form of the book has been helped by efforts from a group of trusted friends who proofread the material; this included Fried Augenbroe, Cheol‐Soo Park, Georg Suter and Wei Tian. Feedback on parts was also obtained by MSc students at both Georgia Tech and Plymouth, which helped me to develop the material. Any remaining misconceptions and errors are my own responsibility. Further thanks go to Paul Sayer and the team at Wiley who managed the production of the work.

Finally, I would like to thank Anke, Rick and Tom for tolerating the long hours that were invested to realise this book. Without your love, support and endurance, this work could not have been completed.

Many disciplines are concerned with aspects of building performance and its analysis. Surprisingly, little work exists that presents a comprehensive and systematic overview of this diverse and growing field. This timely book by Pieter de Wilde, a leading researcher and practitioner of building performance analysis, thus fills a significant gap. The book guides readers through a wide range of topics from theoretical foundations to practical applications. Key concepts, such as performance attributes, performance targets or performance banding, are introduced, as are the methods to measure and evaluate building performance. Topics of both scientific and practical relevance, including decision making under uncertainty or data collection and analysis for improved building operation and control, are reviewed and discussed. Readers will appreciate the comprehensive coverage of relevant research and standards literature, which makes the book particularly valuable as a reference. In summary, this book is highly recommended reading for both novices and experts who are interested in or want to learn more about building performance analysis.

It sometimes is a challenge to write a book to describe the things we always talk about. Dr. de Wilde deals with the important topic of ‘building performance’. This sounds easy, but actually the subject is very complex. Yet we must define the meaning of building performance before designing and constructing green buildings, low‐carbon buildings or high performance buildings. After a thorough review of state‐of‐art research on building performance, this book presents an ‘emergent theory’ of building performance analysis. This book will play an important role in a deeper exploration of this fundamental topic.

Over the last two decades, I have been involved in simulation studies of more than 20 existing buildings in the United States and South Korea, analysing the performance of double skins, HVAC systems (such as the example briefly introduced in Chapter 6 of this book), occupant behaviour, machine learning models for building systems and many others. However, it has never been easy to unambiguously quantify building performance of these cases. For example, how can we ‘objectively’ quantify the energy/daylighting/lighting/thermal comfort performance of a double skin system under different orientations and changing indoor and outdoor conditions? The performance of this double skin is dependent on design variables (height, width, depth, glazing type, blind type), controls (angle of blind slats, opening ratio of ventilation dampers usually located at the top and bottom of the double skin), occupant behaviour (lights on/off, windows open/closed), HVAC mode (cooling/heating) and so on. As this example shows, objective performance quantification of a double skin is not an easy task. Moreover, so far there is no established theory or set of principles to help us direct the analysis of building performance at different building and system scales. The general way we presently describe building performance is at best a ‘relative’ comparison to a baseline case. This book by Professor de Wilde attempts to fill this void and presents an emergent theory of building performance analysis. I have observed for several years how Professor de Wilde has worked hard to complete this invaluable book. I firmly believe that it will contribute as a foundation stone to the area of building performance studies and will support efforts in this field for many years to come.

At last, a book that answers the question ‘what is building performance?’ not by theory alone, but through analytics and impacts on building practice. Pieter de Wilde has crafted a comprehensive compilation of what building performance truly means – from its place in the building life cycle and its relationship to stakeholders – through systems, technologies and the unpredictable occupants who often have the most influence on how buildings perform. The book goes beyond the merely theoretical by demonstrating the analytics, tools and instruments needed to evaluate building performance in practice. The case studies are relevant and specific to the system or technology but also to the appropriate part of the building life cycle. By the end, Pieter de Wilde ties it all together through life cycle phase specific theories for evaluating building performance – design, operation and research. Well written, insightful and a pleasure to read.

This is a long awaited primer for those studying performance, simulation and analysis of buildings. As a subject, building performance analysis borrows from a wide variety of viewpoints and disciplines. This book takes on the difficult task of consolidating these together and goes a step further in articulating the particular nuances of building performance. It is the first book on building performance that goes beyond current trends in research and instead reflects on its foundations, remit and reach. The book is sure to become an essential read for graduate students wanting to grasp the breadth of the subject and its roots. The clearly identified reading list and scenario exercises (activities) at the end of each chapter are fantastic; they help the reader go beyond the text and are particularly valuable for generating discussion sessions for graduate courses.