Generally, the best, least wasteful way to create a new, green building is to preserve and improve an existing one. But when the buildings in question are hundreds of years old, they can pose some special challenges, both from a preservation and energy efficiency point of view.
In San Francisco, the Presidio Trust, which manages the Presidio of San Francisco, an urban national park (and former Spanish, Mexican and finally U.S. military base) located at the base of the Golden Gate Bridge, is succeeding in its efforts to update the park's landmark structures while preserving their history and making them drastically more energy efficient.
And in doing so, it's using decidedly modern technology.
The Officer's Club, which dates back to the early 1800s, is the Presidio's -- and San Francisco's -- oldest building. It's undergoing a complete rehabilitation that includes the repair and restoration of all significant historic spaces, the construction of new exhibit space and event venues, and seismic upgrades and improvements to enhance accessibility for people with disabilities
The Trust is employing a combination of thermography and radar scanning to identify the adobe bricks in the building's walls that need to be replaced. This way, only the sections of walls that are not up to snuff are fixed and the parts of the walls that are sufficient remain in place.
Thermal imaging is used first, says Clay Harrell from the Presidio Trust's media relations department, and with it, preservationists can scan large areas of the building, in order to survey surface temperatures and identify wet areas or voids, which represent areas of concern in the structure. Then, to confirm what the thermal images show to be weak areas, an impulse radar scanner is used.
Based on this approach, the Trust won an award this past weekend from the California Preservation Foundation, recognizing its innovative approach to selectively replacing the adobe bricks. The Officer's Club is slated to be completed by the end of 2012 and the project is expected to receive a LEED gold certification from the U.S. Green Building Council.
The Presidio is one of the largest and most ambitious historic preservation projects underway in the United States and the Trust and its partners have won a total of seven Preservation Design Awards since 2000. Other projects include the transformation of a unused former military hospital into a high-end LEED Gold certified apartments and the rehabilitation of a former army airplane hangar for La Petite Baleen, a children’s swim school.
Photos via Presidio Trust: Scanning the adobe wall using impulse radar equipment (top); thermal image of the Officer's Club exterior