The Department of Energy should lead by example. The Forrestal Building is known to be terribly energy inefficient, and occupants of the building almost universally hate it because of lack of daylight, uncomfortable temperatures, etc.
My suggestion is to move DOE headquarters from its current location in Forrestal to the Constitution Center (400 7th St SW). The owners of that building have made such a proposal and claim that it would be essentially the same cost as the current building, but so far DOE has not acted on this idea (as far as I can tell).
The Constitution Center is expected to become LEED Gold certified and would save some 20% in energy costs. The building is designed so that all occupants could have access to daylight, and be able to set the temperature in their work area to within a few degrees. The building is large enough to hold all of DOE's Washington employees--including Forrestal and L'Enfant.
Further, the building has the highest security measures of any building in DC. For example, the windows have level 4 blast protection, which means the it can be continuously occupied.
Moving our offices there would be a big public relations win for the department, and for the Administration in its efforts (and Executive Order) to reduce energy consumption by federal agencies. Employees would be more comfortable and happy--which demonstrably improves productivity. This move makes sense. We just need some leadership from above to help us cut through the paperwork and make it happen quickly.