Mechanical attic ventilation, such as an attic fan, is often promoted as a way to cut heat gain in a house. However, the effectiveness of any attic fan will depend on several factors, including the amount of insulation in the attic and natural ventilation.
“It could be 82 degrees outside and, depending on how well the attic is passively ventilated, at peak heating hours the attic could reach 140 degrees or higher,” said Rick Richart of Richart Builders and Remodelers in Vancouver. “When the fan pulls out hot air, it replaces it with outside air. If the attic is well insulated, the fan will help protect the inside of the home from that hot air.”
However, if the attic has inadequate insulation, blocked soffit vents or is not well sealed from the rest of the house, the fan could end up pulling cooled air from the living area into the attic. This will increase your energy bills if you have air conditioning—not to mention do nothing to add to the comfort of your home.
For more information, contact Clark Public Utilities Energy Conservation Counselors at 360-992-3355.