Mandate that each office has a responsible energy policy.
Even bathrooms at federal buildings use a lot of water when toliets are flushed. The amount of water used per flushed could be decreased.
Lights do not need to be left on all the time. The office could install motion detectors that switch power off of lights (or electrical outlets) 2 hours after movement has stopped. Items still plugged into an outlet use electricity. Most of the time a printer does not have to be plugged in all weekend. This is simple to change and do. It is not prohibitively expensive to purhcase or install these energy saving devices.
Programmable thermostats can be tied into this policy as well . These are items we use in our homes to save us money and it would save the government money by doing this to.