Here's an example of local preservation of historic architecture, the old Vista del Arroyo Hotel, now the home of the Ninth Circuit Court. I worked on it in 1985 to finish out some of the chambers and offices of the judges while working at NTD in Pasadena, a very interesting project. This work did not include the historic bungalows which were restored as part of a later, very controversial project. The hotel was listed in the National Register of Historic Places since April 02, 1981.
This is one of the most visible landmarks in Pasadena, especially as you enter from the west, perched in the hill overlooking the Arroyo Seco. The structure was built in 1920-1937 by architects Marston Van Pelt & Maybury when earlier wooden structures were demolished. It was once commandeered as a WWII Army hospital, and eventually was purchased by the Federal Government for use as a courthouse. A more complete history is here.
The structure was adapted to courthouse standards of the time, with separate circulation for the judges, the public, and the defendants facing trial, usually handled with a separate circulation and holding system. The old rooms and corridors were remodeled for the offices of the judges, and a new "en banque" central courtroom was designed, along with a research library and a commissary. All at the same time that the basic historic features were being preserved. This kind of preservation and adaptive reuse goes a long way towards conservation of embodied energy and also demonstrates the efficiencies of upgrading the mechanical and electrical systems to save power and water.
Is Historic Preservation "Green"? It can be one of the best ways to go if it's done right and the new use of the structure is compatible with its configuration, scale and design.