How Does a Whole House Attic Fan Work?

Last week we started talking about ventilating your home by installing a whole house fan. This week, we thought it would help if we explained a bit more about how whole house fans work, as well as the right time of day you should run your whole house fan, to get the most out of its cooling effectiveness.

The short answer to how a whole house fan works for cooling your home is … Very Well! That’s because most home owners who install a whole house attic fan are very pleased with its performance, and the way it helps cut back on cooling costs by using a method similar to convection to remove heat. The fan cools the temperature within your home by rapidly exchanging the existing hot air for fresh, cooler air from outdoors. It’s one home improvement project where you can hire an electrician, and have much cooler temps in the home within a few hours!

Placed in the ceiling of your home’s top level – the attic floor in other words – the fan creates a vacuum when turned on which will first draw the hot air from your house into the attic where it will leave through vents in the roof, gables, or eaves. As the fan runs, cool air from outside is continually drawn into the home to maintain a comfortable environment.

When to Run a Whole House Fan

According to the Consumer Energy Center, most homeowners run the whole house attic fan in the evening or at night, turning it off before daytime air temperature begins to rise. It is important to note that the fan should be run long enough to not only exchange warm air for cool air, but also long enough to cool off the home’s walls, furniture, and floors. Otherwise, they will radiate stored heat if the fan is turned off before they are cooled.

When the fan is off the shutter automatically closes, preventing warmer air in the attic from seeping back into the house. Homeowners also use their whole house attic fan to freshen air when cooking, painting, cleaning, or doing other activities that create odors in the home.