I posted recently about three houses that were built to stay cool without air conditioning. But what about those of us who live in older, pre-existing homes and don’t have the means to retrofit?
My friend and green renovation expert Matt Grocoff, host of Greenovation.TV, offered up this wonderful solution in an article on Old House Web. If you have a basement and a second-floor window, Matt says, you’re in luck. Just follow these five steps to 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,” Matt writes. “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.”
Matt and Kelly Grocoff take advantage of their 110-year-old home's natural ventilation to keep it cool without turning on the AC.
In his own 110-year-old Mission Zero House—the nation’s oldest net-zero energy home—Matt and his wife, Kelly, restored every window and added energy-efficient storm windows with low-E glass. Built before air conditioning, the home has ventilation features that move warm air through the home and out through the attic. On hot days Matt and Kelly close all the Victorian home’s windows and doors but leave open one gable window in the attic (with a small box fan) and one window in the basement. Warm outside air is drawn through the open window into the basement, which helps chill it. The open attic window draws the warm air up through the house and out, in a movement referred to as the “stack effect.”
“If all is working well you should be able to stand in your basement doorway and feel the cool air blowing up the stairwell,” Matt writes. “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 AC is ultra-efficient, but nothing beats virtually free natural ventilation.”