dcsimg

How To Cool Your House Without Air Conditioning

By: Matt Grocoff , Contributing Writer
In: Old Houses, Home Improvement Tips, Green Renovations, Garden And Lawncare, Technology, Old House Blogger Contest, Historic Preservation

Record hot temperatures getting you down?  Well if you live in an old house and have a basement and a second floor window then you’re in luck.  Whether or not your have air conditioning you can follow these five steps and stay cool without raising your energy bill.

  1. Close all of the windows and doors in the house,
  2. Open one window on the uppermost conditioned space in your house,
  3. Place a small window fan fitted to the window (optional),
  4. Open one window in the farthest corner of the basement or the north side of the lowest floor,
  5. Sit back and feel the cool breeze stream through your house.

Before you can naturally ventilate your old house, you must reactivate the original ventilation features of the house like the attic and basement windows. Many old homes have basement and attic windows that have been sealed shut. In some cases, these have been sealed to try to keep out moisture. Big mistake. Unfortunately, sealing up basement windows to keep out moisture ends up trapping moisture inside instead.

In our 110-year-old Mission Zero House we restored every window in the house, including the basement and attic gable windows. Then we added energy efficient storm windows with low-E glass. By using the home’s original ventilation features we can take advantage of what’s know as the “stack effect” and naturally ventilate the house the way it was intended.
The stack effect is basically the movement of air through the home created by rising warm air. If you’re home is not properly sealed and weatherized the stack effect can be a bad thing; in the winter warm air rises, exits through leaks in the roof and draws cold air in through all the leaks in the lower levels of your house.On hot days we close all the windows and doors, but leave open one gable window in attic and one window in the basement. We put a small box fan in the gable window to give the stack effect a little help. The warm air is then drawn up through the house and out through the attic window.

The stack effect has rules. One rule is that if air goes out it must be replaced by air coming in. Since the basement window is the only other window open in the house, warm outside air is drawn into the basement. The cool basement helps chill the incoming air. As a bonus, the air movement helps keep the basement dry and well ventilated.

In our folk-Victorian we have a basement door next to the parlor that we keep open on hot, less-humid days. This allows the cool basement air to come into the living space as the warm air is drawn out through the open attic hatch and window. If you don’t have a conditioned attic this can still work well by opening a top story window.

A note of caution: make sure you address any mold, gas leaks or radon issues you have in your basement before using it to bring fresh air into your living space. Once you’ve removed any mold, keeping the basement air moving and well ventilated will help prevent the mold from returning.

If all is working well you should be able to stand in your basement doorway and feel the cool air blowing up the stairwell. Two weeks ago on an 85 degree day I was able to keep our home at a nice 73 degrees all day long without needing to turn on the geothermal air conditioning. Sure the geothermal a/c is ultra-efficient, but nothing beats virtually free natural ventilation.

Matt Grocoff is host of Greenovation.TV, a contributor to The Environment Report on Public Radio and the green renovation expert for Old House Web. His home was honored as one of USA Today’s “Seven Best Green Homes of 2010″ and Preservation Project of the Year.  He has been featured in hundreds of publications and news shows including USA TODAY, Washington Post, Detroit Free Press, Miami Herald, Preservation Magazine, Solar Today, Fox Business News, Huffington Post and more.  Join him on Twitter and Facebook

Share/Save/Bookmark

Post a Comment

Enter the text shown above

  1. 7 Responses  to “How To Cool Your House Without Air Conditioning”

  2. James Gu
    Jun 8, 2014
    Hi Matt, Thanks for this great post. I can attest to the fact that passive cooling via natural convection has been working well for years, even in our newish home here in Toronto, Canada. By opening the basement windows and the attic trap door, we barely need any air conditioning while neighbours' AC units hums away electricity. There are a few things that everyone reading this should keep in mind: 1. Beware of humidity. On a hot humid day, by doing this, you can potentially induce condensation in the basement. Depending on the dew point, you might need a dehumidifier or be better off with AC. 2. While you don't need any breezes outside for this to work, don't expect cool air to blast through your basement door. The air speed is usually very gentle. It's a house-cooling method, not people-cooling. If you need immediate gratitude, use a fan. 3. Positioning of the windows is important. You'd always want to have an inflow window to be facing/in a shaded or pre-cooled area. Hope this helps, and thanks again for this great article.
  3. Jade Hoffman
    May 20, 2014
    My AC unit would shut down so much during the day that it drove me crazy. I was prepared to just throw it out when my brother recommended Atlas Trillo in San Jose CA. I’m so happy I listened... They did an amazing job! My AC now works like new! I recommend them for AC servicing, visit their website www.atlastrillo.com.
  4. Nauman
    May 16, 2014
    Indeed it is a great idea that you have brought to public attention. However, there are some point that you missed and should have been remembered. The kind of home cooling that you want to promote works well in areas where the winds keep flowing all day and night long. Otherwise, areas where winds do not flow, installation of air conditioners would serve better than simple home designing.
  5. Oct 15, 2013
    Hi Matthew. That's the case where I live in North Carolina. Its stay pretty warm all year long(goes down a little bit during winter). But that's a good technique for cooling the home and saving money. I'm trying to go into more of the green air conditioning field.
  6. Jeff
    Jul 26, 2013
    I live in northern NJ. It is 85 degrees today. I did as you told, except i put a 20" box fan in the attic window at high speed. I then taped some toilet paper (or should i say "bathroom tissue"?)to the top of the door frames leading from the basement to the attic. They didn't move an inch. What am I doing wrong?
  7. Marlin
    Aug 26, 2011
    With this method do you draw the curtains or shades on the windows? You must not have cats who want to explore the basement! :)
  8. Aug 26, 2011
    UPDATE: We've had several 90+ degree days since I published this article. We have turned on the geothermal a/c only once. On that day it was over 90 and very humid during the day and the nighttime temp dropped only to 79 degrees. Otherwise, this method has kept the house surprisingly cool. It has even impressed my wife.