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By Barbara Knecht

The sound of silence

Acoustical engineers are more interested in the elegant solution to a difficult problem than they are in endless discussions about what wasn’t done correctly. Northeastern University’s Spiritual Life Center, shoehorned into the second floor of the Ell Center in Boston’s Fenway, is one of those well-resolved predicaments. Office dA, the Boston-based architecture firm, their mechanical consultants, Cosentini and Associates, and Acentech were given an awkward space only 20 by 75 feet and 11 feet 6 inches in height to create a serene and comfortable environment for rituals and individual contemplation. After construction, the finished area had shrunk to 20 by 60 feet with a low, 8-foot ceiling, which is composed of three inverted domes covered with off-the-shelf, perforated aluminum panels.

 

The Spiritual Life Center (above) at Northeastern University was designed by the Boston architecture firm Office dA. The program demanded that the space have a quiet HVAC system, one that could still maintain comfortable temperatures whether occupancy was two people or 200. Photography: © Dan Bib

At any given time, the center may be occupied by two people or 200, so the acoustics and the mean temperature will vary greatly. “This is the kind of space where the HVAC system needed to be as silent as possible, and the constrained space made it especially important to come up with a solution that incorporated the mechanical systems with the noise control and the architecture,” explains Acentech’s Sturz. “A high-velocity duct with high-velocity diffusers creates quite a noise; a more sensitive solution for noise control would be to distribute the diffusers throughout, but in this case, that would have been highly intrusive to the architecture. What you need to reduce noise and provide sufficient air are large ducts pushing air at a low velocity.” The solution was to use the space above the domes as pressurized plenums to distribute the air into the space. There is a main duct that runs down the center over the domes and branch ducts that let the air out into the plenums. Large perforations in the ceiling panels permit the passage of air into the space, and smaller perforations provide sound absorption. Some of the glass panels that line the side walls are raised so the air can return at the base of the wall. As Office dA principal Nader Tehrani says, “Acoustics and environmental control overlap in one seamless system.”