This specification provides detailed selection criteria for five major APSs, and sets standards for modeling APSs. It is intended to help those who procure APSs select the most effective models for their commercial buildings. It also aims to encourage building owners and operators to promote the use of the specification within their organizations and information technology procurement officers. Elements of the specification that are labeled as “optional” in italics are encouraged because they may yield additional energy savings or achieve a higher level of user acceptance. If all building owners adopted this APS specification, U.S. commercial building energy consumption could be reduced by 1% (equivalent to $606 million or 63 trillion Btu annually, based on 28% savings demonstrated in the study in citation ).