This report summarizes and compares two currently available commercial building energy-benchmarking tools. One tool is the U.S. Environmental Protection Agencyﾒs Energy Star National Energy Performance Rating System, which is a national regression-based benchmarking model (referred to in this report as Energy Star). The second is Lawrence Berkeley National Laboratory's Cal-Arch, which is a California-based distributional model (referred to as Cal-Arch). Prior to the time Cal-Arch was developed in 2002, there were several other benchmarking tools available to California consumers but none that were based solely on California data. The Energy Star and Cal-Arch benchmarking tools both provide California with unique and useful methods to benchmark the energy performance of California's buildings. Rather than determine which model is "better", the purpose of this report is to understand and compare the underlying data, information systems, assumptions, and outcomes of each model.