Stay Cool + Save Money with Fans

It’s summer, and when the temperature rises, so do most people’s energy bills as they try to stay cool.

We know that fans use far less energy (25 to 100 watts) than air conditioners (500 to 3,500 watts, depending on window units versus central air), but what’s the best way to use them to maximize their cool-down effect and get their energy-saving benefits, too?

These ideas will help.

Create a breeze inside each room.

Unlike winter, when you’re trying to avoid wind chill, a summer’s wind chill is a sweet sensation: That’s what fans create, by causing the room’s temperature to feel 4 to 8 degrees lower when its breeze passes over you.

Space-friendly tower fans, oscillating fans, and ceiling fans are all great options for moving air around your home. Fans with a higher cubic feet per minute (CFM) rating, which measures the volume of air circulating per minute, will give you more air movement, and thus more body cooling. The average 250 square foot room needs at least a 670 CFM rating to create a decent cooling effect.

Energy-saving tip: Remember to turn fans off when you leave the room, as there’s no real change in the room’s overall temperature with these fans. In fact, a room’s temperature may even go up a little if you keep fans on when you’re not there because heat from the fan’s motor will add to the overall temperature.

Move hot air out, or cool air in.

Whenever the temperature drops and it’s cooler outside than it is inside your home, you can turn on the window fan to bring in the outside air.

The trick is to use a window fan correctly. Make sure yours fits tightly in the window with no gaps, like an air conditioning unit, so that it doesn’t blow in the air that is being warmed by the fan’s motor.

You can get even more cooling power by using one fan to draw cool air in and another fan, preferably on the other side of your home with a direct line from the first fan, to push hot air out. Because temperature drops usually happen in the evenings, electricity costs will be lower than during the day, so it’s a savings “twofer” — lower priced energy and a lower energy-use appliance than A/C.

Window fan cooling caveat: Once the temperature gets up to 95 degrees, the benefits of window fans might not be as great. According to a 2012 study, when outside air temperatures rise over 95 F, using an electric fan can actually increase your body’s heat stress by blowing air that is warmer than your ideal body temperature over your skin. It can even raise your body’s temperature, unless you are very wet and can benefit from the cooling effects of evaporation.  All is not lost, though.

Bonus trick for a little extra chill blast (with any type of fan).

Freeze a couple of 2-liter water bottles and place them in front of the fan as it blows. According to some estimations, this technique can make up to an 11-degree difference in air temperature. When it’s hot, every little bit helps. This trick has the added benefit of making sure your freezer stays full, which helps it run more efficiently, thus saving you energy and producing less heat from the appliance’s motor, too. (In contrast, your refrigerator should be less tightly packed to run most efficiently.)

Cool your whole house with a fan.

If you’re a homeowner, a whole-house fan may be the way to go. This type of fan is installed in the ceiling between a living space and attic. When the windows and doors are open, the fan pulls air through a living space and pushes it into the attic space, then forcing the air through the gable and/or soffit vents. Many have louvers that automatically open and close when you turn on and off the fan to hide it. Depending on your installation, a whole-house fan can move air at a flow rate of 4,000 to 7,500 CFM. That means that if a home has 1,500 square feet of living space, the air can be thoroughly refreshed every two to three minutes with a whole-house fan for considerably less energy than air conditioning.

When used in conjunction with other basic cooling techniques, such as staying well hydrated, frequent, quick showers, closing curtains where direct sunlight shines in, fans can make all the difference at helping you stay cool and save energy this summer.

Laura Dobbins

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