Usually when you think of skylights, it's about getting more daylight in the building," says George Petzen, estimator with LinEl Signature in Mooresville, Ind. True. But when the skylight in question covers about 85 percent of the roof of the largest privately held art gallery in Washington, D.C. - and much of that skylight is original to a building constructed in 1897 - then letting in more daylight might be your last concern.
"It's an art museum, and the existing glass was wired glass on the exterior and a rolled textured glass ... they weren't readlly cutting down on any UV," Petzen explains. "[The owners] were starting to get very concerned about the longevity of the artwork on the wall."
Damaging UV rays were one motivation for the Corcoran Gallery to begin restoration on the roof of its historic building early last year. The roof covers approximately 48,000 square feet - the magority fo which is glass - and features multifaceted structures with varying types of construction, drainage and elevations. Further complexities have been added to the design by later replacements and alterations, including the addition of a wing in 1927. No comprehensive repair program has been undertaken to address the roof and skylights since the early 1980s.
In addition to controlling the light and heat transmitted into the interior, museum officials note that the restoration is intended to seal off the building from moisture and update the climate control equipment located in the attic. The flat roof was replaced and the elaborate skylight system retrofitted with new glass to control the heat and light transmitted into the galleries.
"Because there's so much volume to [the skylight] they were looking to improve the thermal efficiency of the building envelope," Petzen adds. "Half-inch wired glass isn't very thermally efficient. Going to high performance low-E and ceramic frit accomplished that for them."
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