Nick Baker is a course tutor at the Architectural Association. While he originally studied physics he has nevertheless spent most of his professional life working in architecture and building. His interests include energy modelling, daylight design, natural ventilation and thermal comfort, as well as the broader field of sustainable design. He has written and contributed to several books on these topics, including a book on Sustainable Refurbishment partly based on material from a recent EU funded demonstration project, where he served on the expert panel. More recently he has become interested in the way occupants interact with buildings, and in particular, the way their behaviour influences energy use. Now retired, for much of his career Nick was a lecturer at Cambridge University Department of Architecture, and is a visiting lecturer and external examiner at several other universities. Koen Steemers is Professor of Sustainable Design in the Department of Architecture, University of Cambridge, Professorial Fellow at Jesus College, and is a Director of the architectural practice CH+W Design. Previously he was Head of Department (2008-14) and Director of the Martin Centre for Architectural and Urban Studies, the research arm of the Department of Architecture at the University of Cambridge (2003-08). An architect and environmental design specialist, Koen was recently listed as one of the "top 50 most influential people in UK sustainability" by Building Design. His current work deals with the architectural and urban implications of environmental issues ranging from energy use to human well-being.