I think it’s great that the newest Pentagon auxiliary structure will be the DOD’s greenest office building yet but if they really wanted to be environmentally conscious they wouldn’t have located it “a mere 7 miles down I-395 at Mark Center,” they would have put it right next to the Pentagon where currently a gigantic open-air parking lot is occupying some extremely valuable land:
If you replaced all those lots with office buildings featuring underground parking garages, it would still be possible for DOD personnel inclined to drive to do so. But, obviously, parking would be expensive and many people would choose instead to avail themselves of the conveniently located Pentagon Metro Station. To cope with the increased demand you would also want to beef up the frequency with which the bus lines that serve the Pentagon arrive, and possibly even launch a new line or two. The environmental benefits of that kind of arrangement would be considerable.
Generally one substantial problem we have in the national capital area is that the federal government, being the federal government, faces no real financial pressure to use its space in an efficient way. Congress maintains a lot of open air parking lots in the vicinity of the Hill that a private company would almost certainly turn over to developers. That would add jobs and houses to a dense, walkable, very transit-accessible area. But of course the members of congress and their staff couldn’t personally pocket the money thereby earned, so they have no real incentive to do so.