COLUMBIA, S.C. — As temperatures continue to soar into the 80’s and 90’s well into September and October, many people are looking for ways to save some money on your energy bill. Often homes are built with attic ventilation fans. But will running that during hot weather actually save you money?
We set out to Verify. Our sources for this story are Christian Kaltreider, an Energy Efficiency Researcher at the Pacific Northwest National Laboratory, which is a Department of Energy Lab and Kenny Wardlaw, Owner of Cool Care, Master Mechanic with 40 years of experience.
Kaltreider explained the idea of the fan. “They used to be installed because people believed they could remove hot stagnant air from the attic and circle back in cooler air from outside and cool down my living space below," he said.
But in warm, humid climates, that backfires, because the air brought back into the home is hot and the fan can actually suck the cool air conditioned air straight from your lower floors.
Kaltreider said, “beyond the power consumption of attic ventilation fans, it creates a negative pressure zone in the attic, and the negative pressure zone can pull cooled air conditioner air from the living space, and that air is replaced with hot moist outside air "
Meanwhile Wardlaw explained why bringing moist air back into your attic can create another round of problems. He said, “The hotter the air, the more moisture it can hold. If you bring hot air into the house, when it cools it leads to moisture and biological growth. And that’s something you definitely don’t want in your attic since many people don’t go up there regularly to check, it can become an issue quickly."
Also Kaltreider explained studies done by the Department of Energy have shown that the money spent to constantly run the fan is more than any money that could be saved.
Both experts agree the best way to keep the attic cool is to add insulation and air seal your attic floor. So we can verify, if you are in a warm moist climate, running your attic ventilation fan will not save you money on your power bill.