HVAC Equipment Can Overpower Wind and Stack Effect

HVAC Equipment Can Overpower Wind and Stack Effect

Mechanical pressure usually beats natural pressure Mechanical forces created by fans — either ventilation fans or furnace fans — can completely overwhelm wind and the stack effect Also referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season. . “If we blow air into a building, we pressurize it,” Straube says. “Everywhere. If I have a 10 Pascal pressurization, it will spread through the whole b...

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