from Emil in Berlin, WI:
#856
Does it pay to install solar-powered attic fans in the roof to bring down the attic temp?
Yes, use a fan in the summer.
Yes, it would be beneficial to reduce attic temperatures during the summer months by operating a solar-powered attic fan. However, it would be unwise to allow the fan to operate during the winter months in a cold climate such as Wisconsin, as its operation has the potential to pull conditioned air from the house into the attic through air leakage sites in the floor of the attic. The problem with that is moisture in vapor form associated with that conditioned air can condense on cold surfaces in the attic. Condensation in an attic can cause a variety of problems to include degradation of structural components (trusses, rafters, joists, roof decks, and more). Condensation can also degrade attic insulation thereby reducing its effectiveness. Bottom line… use a solar-powered attic fan in the summer months only if you live in a northern climate.
Published Thursday, August 05, 2010