Taken as a whole, this ebook highlights a number of important issues. It is fair to say that over the past 40 years, the poor uptake of energy retrofit technologies has resulted in both an 'energy efficiency gap' and an 'energy performance gap', revolving around how buildings perform in 'theory' and in 'practice'. Examining the reasons for this and helping understand how the sector can change is vital. So, in understanding energy efficiency projects in commercial property, we will need to bring together a range of different disciplines to analyse the complex inter-relationships between technology, economics, value, legal issues and behaviour that exist in this arena. Only in this way will we be able to help inform the debate, and create a more reflexive, proactive, and problem-oriented response in the sector.