Many of the computers running on government networks are left on, running at full power 24/7, yet they are only used between 5-8 hours per day. This is like leaving a 100 watt light bulb on all the time, even when no one is in the room. Simply mandate that all local IT staff enable the most efficient Energy Star settings on every computer.
Install motion detector lighting in offices to limit the amount of lights left on. Energy savings= money savings. In the hundreds of thousands of federal offices this would add up quickly.