The conservation of fuel and power in buildings is an important part of the UK governmenta s strategy to reduce national energy conservation. The revision to Part L of the Building Regulations, which came into force on 1 April 2002, lays down detailed and extensive requirements for conserving energy in almost all buildings and it covers most potential causes of building energy consumption. This guide explains these detailed requirements and shows how they apply to particular cases, with the use of numerous worked examples. It includes a chapter on air tightness and leakage testing, a topic with which many building professionals are unfamiliar.