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.
- Close all of the windows and doors in the house,
- Open one window on the uppermost conditioned space in your house,
- Place a small window fan fitted to the window (optional),
- Open one window in the farthest corner of the basement or the north side of the lowest floor,
- 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