A whole house fan is a high-capacity ventilation system that rapidly exchanges indoor air with outdoor air to cool homes and improve air quality. These fans pull cool outside air through windows and exhaust warm indoor air through attic vents, providing natural cooling without air conditioning. Whole house fans are most effective in climates with cool nights and low outdoor humidity.
Technical Details
Whole house fans typically operate at 4,000 to 20,000 CFM, requiring attic ventilation area of at least 1 square foot per 750 CFM of fan capacity. Installation requires proper ducting from living spaces to attic intake and adequate attic outlet area. These systems reduce cooling costs by 30 to 50 percent in suitable climates and operate at significantly lower power consumption than air conditioning units.
Applications and Practical Significance
Whole house fans are ideal for inland and desert climates where nighttime temperatures drop substantially. They provide rapid air exchange rates that improve indoor air quality and help manage seasonal cooling loads. Proper installation includes safety dampers and airflow balancing to prevent backdrafting through combustion appliances.