Using Window Fans to Cheaply Cool Your Home

In the long term, you can manipulate the temperature of your home’s interior by adding insulation, weather-stripping, planting trees, reroofing with white shingles, adding glass to let in sun, and installing wood-burning stoves. Doing these things will let you better keep the heat outside or inside (depending on the season) so you and your family remain comfortable without going bankrupt.

Other than installing weather-stripping, all those methods take time, effort, and money, sometimes substantial amounts. What can you do in the meantime?

Cue up the music for the window dance.

That’s the dance we perform every morning. We move from window to window and do what’s necessary. In winter, it’s to open the treatments to let in the sun. In summer, it’s to open the windows and hope for a breeze to cool off your house.

This is where fans come in.

You expend small amounts of money and effort that will make your windows more effective in cooling your house, and it will certainly be cheaper than running the air conditioner. If you have double-hung windows, you can use set-in-the-window-frame electric fans. If you’ve never seen one, these are a pair of small fans, set into a plastic housing side-by-side. These units sit inside the window frame, with the cord extending to the nearest outlet. They normally come with plastic extenders to help them fit better into your window.

Window fans are not box fans nor are they free-standing fans, either the small ones that sit on your desk or the big floor models. Free-standing fans won’t work for this method. Box fans work only if they fit safely and snugly within your window frame. They tend to be so big, heavy, and tippy that they quickly become a safety risk.

Window fans fit best inside double-hung windows but you may be able to use this method with casement or sliding windows. You’ll have to see if the fan fits snugly within the opened window, not quite touching the screen.

You’ll want several sets of window fans, but you won’t need a unit for every window. The goal is to bring in cool air at one end of your house while blowing out hot air at the other end of the house. This works best at night as the air temperature drops on its own, and you are not fighting the solar gain.

Where to place window fans

First, notice where your prevailing breezes come from, especially at night. Do they conveniently line up with the orientation of your house’s windows? If so, your job just got easier. If not, oh well. On the side of your house, where the breezes want to come in, open your windows and insert the window fans after the sun goes down and it starts to cool off. Close the sash to help hold the window fan in place. Adjust both fans to blow in at high speed, bringing in that cooler air.

At the other end of the house, insert more fans and adjust them to blow out at high speed. If your house has several floors, put a set of similarly arranged fans on each floor. Let the fans run all night, exchanging an entire day’s worth of hot, stale air for fresh, cooler air.

As for your other windows: you’ll have to experiment. You may discover that you have to close them completely to encourage airflow, you might be able to leave them partially open, or you can leave them open all the way. Each window in each room may have to be addressed separately.

If you can afford to, you can use more fans blowing in and blowing out as appropriate. The key is to exhaust air out of your house at one end so the vacuum you create encourages cool air to come in, including via windows that don’t have fans.

There’s an alternative method that’s recommended by the box the fans come in. It suggests that since there are two fans, set side-by-side in one unit, you can use one side to bring in cool air and one side to exhaust warm air.

This has never worked for me. Maybe if you have a one-room apartment, with one window, you’ll have to do this. But I’d still set both fans to blow in as much cool air as I could.

I also pay no attention to the various speed settings. Some window fans can get quite fancy with a variety of options. I run my fans on their fastest setting. I want that air to move. I’ve done this for years without any problems.

If you close window treatments to block noise or light, remember that those layers of cloth will also block the fans. You cannot block the fans’ actions in any way or the magic won’t work. So keep those draperies well away from the fans.

Morning routine

In the morning, your house should be noticeably cooler. Close up your house as the day warms up, trapping the cool air . This won’t be as fast or easy as air conditioning but it makes hot nights much more bearable and it won’t break you financially.

Take good care of your fans, being careful how you move them in and out of the windows. Taking them in and out of the windows every evening and every morning is the hardest part of using them and the point when you are most likely to drop a fan and break it. Regularly vacuum all the parts you can reach to help maintain that clean air flow. Store them for the winter in their boxes and they should last for years.

I have five fans and in conjunction with the window dance, they allow me to postpone air conditioning until the hottest part of the summer. They let me turn off the air conditioner sooner as the nights get longer. They even let me, if a July night is cooler and breezier than normal, turn off the air conditioner and still cool off my house.

Next week, I’ll talk about ceiling fans next week and how to use them both in the summer and the winter.

Teresa discusses the window dance and other methods to heat and cool your house economically in Fed, Safe, and Sheltered which you can read about here.