This current document represents the culmination of an eight-year effort to compile a comprehensive state-of-the-art reference and instructional tool for practicing design professionals, architects, and engineers. It is intended to cover all phases of the design and installation of active solar energy systems for buildings. Although it contains many design guidelines, the emphasis is on providing sufficient knowledge of how these systems work to allow an engineer or architect to make well-informed decisions. It is aimed primarily at commercial building applications, but most of the material is also applicable to residential buildings. The book is divided into 13 chapters: energy and buildings: a perspective; energy use, cost, and load calculations in commercial buildings; fundamentals: solar energy, climate, and human comfort; active solar heating and cooling systems; principal components of active systems; active subsystem components; active system design and sizing methods; detailed design, construction, and installation considerations; collectors: specification and prebidding; start-up and acceptance testing; developing an operations and maintenance manual; instrumentation and monitoring; construction costs. Each chapter has been indexed separately for inclusion on the Energy Data Base. 241 references.