For warm-climate gov't offices, tint all south and west facing windows. I just did it at my house and it's great! Big savings on AC costs. Little impact in winter!
Department of Commerce
Vending machines' power is left on 24/7. Suggest new snack and soda vending machines be required to be equipped with timer to turn off their power at a certain time of day, shutting off lights and costly refrigeration. Copiers have this feature. Vending machines should too
Measure the power consumption of individual employees (easy using tools like http://SmartOES.com) and initiate competition between different departments, buildings, and programs.
On average this results in 25% energy savings. If applied across the government, this would amount to more than $200,000,000 per year.