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By Sara Hart

“Windows are the weakest link with regard to noise control,” says SM&W partner Denis Milsom. “With subways, the rumble noise is the most difficult to deal with. It’s a low-frequency noise, and it goes through the windows.” Research shows that low-frequency noises disturb people the most. In the case of the Brooklyn building, 85 Adams Street, such problems were anticipated by heavy bridge and rail traffic, so blocking infiltration into the apartments was, predictably, a priority for the developer. The engineer’s solution, therefore, was resolved in the glazing and wall system. The window unit consists of 1¼2-inch laminated glass on the exterior face and a 1¼2-inch pane on the interior, separated by an airspace of 8 inches, resulting in a wall assembly that’s a remarkable 10 inches thick. (The acoustic windows were developed by specialty contractor St. Cloud Windows of Minnesota.)

 

The Mandarin Oriental Hotel in Washington, D.C. (above), is located on an “acoustically challenged” site (below). Photography: Courtesy BBG/BBGM

This airspace is quite deep for nonindustrial buildings. Conventional acoustical wisdom warns that a wide air cavity can create convection within the space, increasing heat loss. Christopher Pollack, SM&W project manager, insists, “The cavity we created was sufficient to meet all the codes required. The acoustical construction consists of very heavy laminated glass, which may actually increase thermal performance.” He further explains, “The frame for this window is in two parts, an outside frame and an inside frame. These are joined by rubber to help break sound from transmitting from one side to another. This acoustical break will also help in reducing the transmission of heat.”