With the adoption of the U.S Energy Policy Act of 1992 (EPAct),1 ANSI/ASHRAE/IESNA Standard 90.1-1989, Energy Standard for Buildings Except Low-Rise Residential Buildings, became the base efficiency standard for nonresidential building codes across the United States. Under this act, each state had until October 1994 to certify to the Department of Energy (DOE) that ithad a building code as stringent as Standard 90.1-1989.2,3 While many states subsequently adopted codes based on Standard 90.1-1989 or subsequent versions, approximately 10 states, includingCalifornia, already had a building energy code.