Attic fans cool the house by creating a breeze through the open doors and windows. If you get an attic fan that is sized for your house, it should only take the fan around 3 minutes to blow out all the hot air in your house. The hot air is replaced with cool air from outside. Attic fans are a great alternative to air conditioning units and whole house fans. They are significantly cheaper. People often get sick from AC blowing cool air directly; attic fans don’t do that. It only takes an attic fan a few minutes to cool down your home.