Shows that the DoE has failed to use the most important and readily available energy-efficient tool: thermostats that automatically ¿set back¿ the temperature when no one is around, especially nights and weekends. During 2008, DoE expended $300 million to provide energy to over 9,000 Fed. buildings. A significant portion of those costs, up to 40%, were expended for heating, ventilation and air conditioning. "Setback" controls, both mechanical and software, decrease the temperature difference between the inside of the building and the outside of the building during non-working hours. This audit determined that the Dept. was not taking maximum advantage of setbacks as an energy savings/management technique.