Attic fans offer several benefits to homeowners.

  1. Energy savings.  An attic fan can lower the overall temperature in your living areas. This keeps your home cooler, lessening the use on your air conditioner and thus lowering your heating expenses.  It is not unreasonable to expect an attic fan to reduce living area temperatures by 5 to 10 degrees, reducing cooling expenses as much as 10%.
  2. Extend the life of your air conditioner.  This reduction in room temperature also means the air conditioner does not need to work as hard, thus extending its life.
  3. Extends roof life.  There are two ways an attic fan can help extend roof life
  • Everyday activities such as showering and cooking create moisture that rises to the attic.  This moisture will eventually create mold in the insulation and perhaps even the wood.  In the winter this moisture will expand and turn to frost or ice, potentially damaging your roof.  An attic fan moves this moisture out of the attic before it can damage the wood.
  • Summer heat can cause your roof shingles to become brittle.  Attic fans can reduce this heat.

When selecting an attic fan, the most important thing you need to consider is the size of the fan.  You need the right size fan to make sure the attic can be adequately cooled.  To do so, measure the square footage of your attic and multiply that by 0.7.  That will give you the minimum CFM (cubic feet per minute) rating for your attic.  You might want to add 15% for dark covered roofs, as they will absorb more heat.