In the U.S., copiers use about 7 TWh/year of electricity, and a similar amount of energy is embodied in the estimated 2.2 million tons/year of paper used in copiers. These cost the economy about $500 million/year for the electricity and $2.2 billion/year for paper. The U.S. EPA launched the ENERGY STAR copier program in 1995 to save money plus reduce energy use and greenhouse gas emissions from copiers. This study evaluated the performance of ENERGY STAR copiers to assess the energy savings they currently achieve and the potential for increasing the savings. The main effect of the program is not to change power used in each operating mode, but to change the amount of time spent in each mode. We defined methods for auditing and energy use monitoring copiers and carried them out on 228 and 11 machines respectively. About 30% of both ENERGY STAR and conventional copiers were left on at night; while most conventional copiers were in a low-power mode, most ENERGY STAR compliant machines were fully off. Extrapolating these findings to all U.S. copiers results in higher electricity use than previous estimates, due to the night and weekend status and longer work days. However, this also implies a greater potential for saving energy with power management from ENERGY STAR copiers. A survey of users found general satisfaction with ENERGY STAR compliant copiers. Enabling of default duplex on two copiers raised their duplexing rate by 15% and 20%.