Whole-House Fans

No. A whole-house fan moves outside air through the home, so when it's a hundred and five outside it moves hot air inside. The strategy is to run the fan at night and early morning when valley air is cool, flush the heat the home absorbed during the day, and let the AC handle the hottest hours. Together they use less electricity than AC alone.

Yes. The fan pushes hundreds or thousands of cubic feet per minute of air into the attic. If the attic can't exhaust that air through ridge or gable venting, pressure builds and the fan loses performance. Attic venting gets checked before any fan install.

Older fans with simple gravity dampers can. Current insulated, motorized-damper models close tightly in winter and don't become a thermal shortcut. For retrofit homes with existing older fans, upgrading the shutter is often part of the install conversation.

The fan requires windows open to work — a home sealed up for an AC night won't benefit from the fan running. In homes near busy roads or where night-time outdoor air quality is a concern (wildfire smoke season), the fan should be off. We walk through the use pattern during install so the owner knows when the fan helps and when the AC is the right tool.