As exciting as it is to see shiny new LEED-certified buildings going up all over town, there’s been quite a bit of buzz lately about how the greenest building is the one that already exists. In recognition of that, three giant buildings that have recently been totally redone, rather than razed and rebuilt.

First up: The full-block building at 3rd and C Street SW that houses the Public Health Service. Over the past year, its blank concrete walls have been partially deconstructed and replaced with vertical ribbon windows, transforming what was once a depressing bunker into a light-filled, modern office building.

Then there’s Gibson Plaza, a Section 8 apartment building on 7th Street NW which has been almost completely gutted and upgraded for energy efficiency. Most of the change is on the inside, with new appliances and better community spaces. But the exterior has been handsomely re-faced as well, with a smooth, limestone-like material on the street level.

Architecture firm Weincek & Associates has creatively redesigned the facade of a large senior housing complex on 14th and Girard Street NW, with painted foam blocks framing the balconies and creating an openness around the entrance—-the kind of aesthetic change that helps change public perception of subsidized housing. The renovation also added landscaping and planter beds in the back.