Retrofit for Purpose explores the art and science of bringing energy efficiency to existing buildings; one of the biggest challenges facing the industry today. The essays and case studies included here explore the main issues, offer practical solutions and provide a clarion-call to architects and clients for better, smarter retrofit. The eleven case studies focus as much on the transformation of usability and image as on the improvements in the energy and resource use of non-domestic buildings. The essay section puts these projects into a wider context, arguing that while there is much more to retrofit than energy efficiency, gathering, sharing and analysing reliable energy performance data are absolutely critical. The authors take a range of other retrofit variables; from client ambition to tenure, budget, use-type, age, context, fashion and fiscal arrangements and assess how retrofit can be made affordable, how it fits in with wider government policy and how performance can be measured. Lavishly illustrated, covering both theory and practice, and with essays from internationally recognised experts, alongside revealing best-practice case studies, Retrofit for Purpose will be of use to architects, developers, other construction professionals and clients alike.