Energy analysis plays an important role in developing an optimum HVAC and architectural design for new buildings and in determining cost effective modifications to existing buildings. In new buildings, it is important that the energy analysis process be implemented for individual design decisions early in the design process. Maximum benefit will be obtained if proper optimization techniques are applied at each step of the evolution from concept to working drawings. In existing buildings a comprehensive energy analysis is the basis for making rational decisions on cost effective building alterations and system modifications. A large number of separate analyses are necessary to adequately analyze the economic benefits of various energy conserving modifications.

The purpose of this text is to present the mathematical foundation for understanding and implementing a simplified energy analysis procedure. The methodology has been in development and evaluation by ASHRAE committee TC4.7 since 1975. Results of preliminary evaluations have shown that the methodology provides good correlation with hourly simulation procedures.