Choosing a Whole House Fan

How Fans Save on Cooling Expenses

Depending on the severity of your summers, a fan can work as an efficient pre-chiller before you switch on your AC, or even as your sole source of cooling. Using only a tenth as much power as your AC, a fan bringing in cooler night and/or morning air can lower inside temperatures by 5 degrees (or more) in just a few minutes. Homeowners living in dry climates with wide day/night temperature swings may be able to do without their AC system by simply switching the fan on during cool hours and then turning off the fan and shutting the house during the hottest times of the day.

Granted, whole-house fans aren’t perfect. They can’t cool inside temps lower than outside temps, nor can they dehumidify. If you live in a humid region, you’ll still need to lean on your AC in the dog days of summer. And while most folks may prefer fresh outside air, if you suffer from allergies, realize that fans draw in outdoor pollen and dust.

Three Types of Whole-House Fans

Standard fan
4,500 to 6,900 cfm
($200 to $450)
Because they’re the most affordable and widely available, large-diameter fans are still a good solution for homeowners living in warmer regions. These fans cost less up front, but installation may be more difficult. Moving a joist in order to frame out a box for the fan, or installing additional attic venting might wind up costing more than the fan itself. Another disadvantage is that during the winter, the vented opening works like an open window, giving warm moist air an easy path out and into your attic. To prevent heat loss, you’ll need to build an insulated box to cover your fan during the off-season.

Insulated-door fan
1,000 to 1,700 cfm
($525 to $769)
If you live in an area with frequent cold snaps, you’ll want a fan that holds in the heat when it’s not in use. Door fans come with insulated (R-22 or R-38) panels that open every time you turn the fans on. This feature not only helps during winter months but also keeps heat out during the summer when you’re running your AC. These models don’t move as much air as standard fans, but they tend to run quieter, so they can be run all night. Like standard fans, these units are usually installed in a hallway, but some smaller models are specially designed to fit in between or around existing trusses or joists to make installation easier.

Inline fan
1,500 cfm (about $235)
Fan/insulated duct units don’t move as much air as standard fans, but by investing in one fan per bedroom, you can provide a breeze effect in the room(s) you most want to cool. The small intake port is not only less obtrusive than the large louvered panels needed with other fans but also easier to install. (A flexible duct connects the intake port to the fan.) Like insulated door fans, inline fans have damper doors within them that prevent warm air from leaking out in winter.