Bad experiences with construction quality, the energy crises of 1973 and 1979,complaints about 'sick buildings', thermal, acoustical, visual and olfactory discomfort, the need for good air quality, the move towards more sustainability - all these have accelerated the development of a field that, for a long time, was hardly more than an academic exercise: building physics. The discipline embraces domains such as heat and mass transfer, building acoustics, lighting, indoor environmental quality and energy efficiency. In some countries, fire safety is also included. Through the application of physical knowledge and its combination with information coming from other disciplines, the field helps to understand the physical phenomena governing building parts, building envelope, whole building and built environment performance, although for the last the wording 'urban physics' is used. Building physics has a real impact on performance-based building design. This volume on 'Applied Building Physics' discusses the heat, air and moisture performance metrics that affect building design, construction and retrofitting.