from Darren in Madison, WI:
#349
I am looking at different options for improving the ventilation in my attic and am interested in some of the solar-powered vent fans that I've seen. I have pretty decent southern exposure on my roof, but I'm concerned that the solar fans will not work in the winter after we get a heavy snowfall (and the solar panels get covered in snow). Are solar attic fans a reasonable option in Wisconsin or are they better suited for warmer climates?
It is best to air seal the floor to attic area.
It is not recommended to use attic fans in our northern climate during the winter months. The reason for this is because moisture-laden (in vapor form) house air can be “pulled” into the unconditioned attic space through many holes and bypasses through the floor of the attic where it can easily condense on cold framing members (trusses, joists, rafters, etc.) or the underside of the roof deck. Because of this, attic fans are not suited for cold climates like Wisconsin. You would be much better off air sealing the floor of the attic to reduce/prevent air leakage into the attic. This measure will also have the added benefit of reducing your heating bill. Using an attic fan in the summer can reduce the temperature of the attic and help reduce air conditioning costs, but again, air sealing the floor of the attic is very important to reduce the amount of conditioned air entering the attic.
Published Thursday, July 30, 2009