What difference can a whole house fan make?
Whole house fans can provide effective natural cooling by using less energy than an air conditioning system. The fans draw cool fresh air in through open windows and send hot air out through roof vents, lowering the temperature of the home and the attic. They can also reduce the air conditioning load for the next day.

While they do not humidify the air, these fans work well whenever the outside temperature is lower than the indoor temperature—typically in the early morning and at night. Using them to cycle out hot air can create a more comfortable temperature throughout your home and cut energy expenses.