Do Attic Breeze fans run at night?

Attic Breeze not recommend operating your solar attic fan at night via an external power source or battery backup. The fan is designed to move faster with the more direct sunlight it receives, typically occurring between the hours of about 11-4PM, assuming that your solar panel is oriented south. During that time period is also when your roof receives about 85% of all the solar radiation it will get for the entire day, which is the driving force behind high attic temperatures. At night your roof doesn’t receive any solar radiation, so there is no additional heat gain to deal with.

If sized appropriately for your home, our products are designed to keep up with the solar radiation heat load throughout the day, maintaining your attic temperature at about 5-15F above ambient temperature so that there is much less residual heat in your attic by the end of the day. By evening time, the only remaining heat will be that from ambient temperature, which your attic insulation is designed to easily handle. Once you reduce the temperature difference between your attic and the inside of your home, your attic insulation becomes much more efficient at keeping the heat out.

Also, it’s a good idea to not operate your attic fan at night, especially in coastal areas. Operating an attic fan at night allows the fan to bring moisture laden air into your attic, leading to mold and mildew problems. This is one of the main reasons we do not offer or recommend a backup power source option for our products. Really, the only time you might need to operate an attic fan at night is if the fan is not powerful enough, or if it is sized too small to adequately remove the daytime heat load for the given attic space size.

If you have additional questions please let us know and we will be happy to help.