Fans, Fans, and Window Fans
Three different types of fans can help you cool your home in different ways: ceiling fans, window fans, and whole-house fans. If you live in a cooler area, you may be able to do without air conditioning entirely just by using these and other tips on keeping your home cool. This is a big plus as mechanical ventilation (fans) use a lot less electricity than mechanical air conditioning (air conditioners).
If you are just using your air conditioner during the day, you can be comfortable with a setting of about 78 degrees Fahrenheit, so long as the humidity isn't extremely high. You can set the temperature for 82 degrees if you turn on one of those slow-moving ceiling fans. The bigger the room, the bigger the fan you will need. Use the following table from Don Abrams' Low Energy Cooling.
|Room Area (square feet)||Minimum fan diameter (inches)|
|over 400||2 fans|
Take advantage of the cool air outside to cool off inside at night. Make sure there is an open window in each room and interior doors are open to allow the air to move through the house. Then shut the house back up tight during the day to keep the cool air inside. If there is a good breeze in your neighborhood, this may be all you need to cool your home without having to pay for any energy at all.
If the breeze isn't strong enough to cool your home, you can add one or more window fans to boost your ventilation. The most efficient way to set up a window fan is to place it in a window on the downwind side of your house. (For you nautical types, that is the leeward side.) So, if the wind is blowing from the north, use a window on the south of the house. Place the fan so that it blows air out of the house. Cool air will come in from the outside to replace the warm air you are blowing out. Remember to keep windows and interior doors open while the fan is on at night and to shut up the house during the day to keep the hot air out.
A whole-house fan may be more convenient, particularly if you need to use three or more window fans to cool your house. A whole-house fan is mounted in the ceiling of an upstairs hallway so that it can suck the air from the house into the attic. The attic needs to have enough vents to the outside. (The rule of thumb is, have twice as much free vent area to the outside from the attic as you have free vent area of the fan opening.)
You can turn the whole-house fan on as soon as the temperature outside drops at least three degrees below the temperature inside your house. As with window fans, you need to open several windows throughout the house and keep internal doors open. If you only have one or two windows open, you are going to cause gale forces through them.
When buying a whole-house fan, look for one with two speeds. The highest speed should be capable of changing all the air in the house quickly. Be sure to install it within an insulated, weatherstripped box with a lid that is either hinged or removable so you lose less heat during cold weather. You also need to install a fusible link to shut the fan down automatically in case of fire.