This study was undertaken for the Arizona Department of Commerce, who requested the U.S. Department of Energy (DOE) provide technical assistance with regard to identifying the major differences in the model energy codes as they might be applied to various locations in Arizona. This study focuses upon the requirements for commercial (non-residential) buildings in these codes. In both codes, “commercial” buildings include high-rise multi-family buildings as well as traditional “commercial” occupancies such as offices, retail buildings, and assembly buildings.