Active solar systems for air heating are a straightforward yet effective way of using solar energy for space heating and tempering ventilation air. They offer some unique advantages over solar water systems, can offer improved comfort and fuller use of solar gains than passive solar systems and are a natural fit with mechanically ventilated buildings. They can be economical, with short pay-back periods and can act not only as space heating or ventilation air heating but also for water pre-heating, sunshading, electricity generation (with hybrid photovoltaic systems) and can help induce cooling. This design handbook takes architects and building engineers through the process of designing and selecting an active solar system from the six types presented, optimizing the system using nomograms and curves, and finally dimensioning the components of the system. Tips are offered regarding the construction and how to avoid problems. The book will provide essential design information for all architects, building engineers and other building design professionals and all those concerned to reduce the environmental impact of buildings.