Whole-House Fan Calculator

How It Works

A whole-house fan is a large fan mounted in the ceiling that pulls cooler outdoor air through open windows and pushes hot indoor air out through the attic. It works best in climates where evenings cool down below 75 degrees F. The fan exchanges the entire volume of air in your home every 1 to 2 minutes, rapidly cooling the structure. This is dramatically cheaper than air conditioning — a whole-house fan uses 200 to 500 watts versus 3,000 to 5,000 watts for a central AC. You must have adequate window area open (about 1 square foot per 750 CFM) or the fan creates excessive negative pressure and noise. Modern whole-house fans are much quieter than older models and include insulated dampers to prevent winter heat loss.