Q & A
Q: I live in a high-rise apartment house built in the 1920s. All the apartment lines have kitchens with windows, except for the line I'm in, which has a kitchenette that is mechanically vented. The hallway outside the apartment also has a vent, which does not seem to draw any air. Instead, my apartment is drawing in air and smells from the hallway and from other apartments. I am concerned that in a fire, smoke could be sucked into my apartment in a similar manner. Is my building in violation of high-rise building codes? What might be a potential solution?
A: "It appears that the building is experiencing problems from the 'stack effect,'" said Peter Varsalona, a principal with Rand Engineering & Architecture in Manhattan.
He said that in cold weather, heated air inside the building rises and then escapes through open windows, ventilation openings and other unsealed areas. "As the warm air rises, it reduces the air pressure at the base of the building, drawing in cold outside air through entrance and exit doors and other openings," he said. "This negative pressure or vacuum is called the stack effect."
The letter writer is correct, Mr. Varsalona said, that this negative air pressure can create a hazard during a fire because smoke can be drawn into apartments.
Before 1968, he said, the New York City Building Code permitted air within hallways to be exhausted, so in a 1920s building, the hallway exhaust fans are competing with the exhaust fans in the apartment bathrooms and kitchens. "If the exhaust fans in the apartments are stronger than the ones in the hallways, the stack effect will be exacerbated, drawing in odors (and in case of a fire, smoke) from the corridors into apartments. (The "new," post-1968, code requires a constant air supply into the hallways, which is good design practice, he said.)
To alleviate the stack effect, Mr. Varsalona said, an air-supply system can be installed in the hallways to deliver outside air into the building, providing positive air pressure in the hallways. (Heating and cooling coils would be required for the new air-supply fan system to temper the outside air supply.)
The building "may want to hire a mechanical contractor or certified testing firm to measure and balance the air flow in the building, and rectify any deficiencies," he said.
From The New York Times, May 4, 2008
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