During the past 20 years, design and operation of the comfort systems for buildings have been transformed because of energy conservation imperatives, the use of computer-based design aids, and major advances in intelligent management systems for buildings. In the 1970s, rules of thumb were widely used by designers. Today, a strong analytical basis for the design synthesis process is standard procedure. This handbook describes the latest methods for design and operation of new and existing buildings. In addition, the principles of life cycle economics are used routinely in design selections and tradeoffs. The information in this handbook is presented in a practical way that building systems.