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April 18, 2014  |  Login
Passive Cooling: Using Physics to Ventilate and Cool Your Home
By Eric Corey Freed

Through the physics of convection, heat rises. Warm air is lighter than cool air, and as the warm air rises, cooler air rushes in to take its place. Passive cooling uses this principle to create ventilation.

You can use this idea to keep cool in the summer by funneling air through your home. Using something called a thermal chimney (a tall, vented space), this rising heat is directed up and out of the house. As wind passes over the building, it pulls more air through the chimney. Cool air from the outside is pulled into the lower part of the house.

Tip: A tall, open stairwell can function as a thermal chimney. Place operable skylights at the top of the stairwell to allow the heat to escape on warm days. You can create air movement even if there is no breeze.


The movement of air, even slightly warmer air, across your skin causes a cooling sensation. The air removes heat and evaporates perspiration, creating the illusion of feeling comfortable. By simply moving air through your home, you can reduce the need for air conditioning.

Here are three simple ways to do that:

  • Operable windows: The easiest way to create natural ventilation is to install operable windows. Locate windows at different heights and onopposite walls to encourage cross-ventilation. Windows placed at the same height will only allow air to pass straight across the room.
  • Bathroom fans: Bathroom fans exhaust the hot, steamy air from your bathroom to the outside. Not only does this lessen the need for air conditioning, but it reduces potential problems with moisture and mold.

Switch boxes for clothes dryers: Install a switch box on the hose of your clothes dryer. In the summer, the hot air is pumped outside, as it normally would. In the winter, flip the switch box to redirect the heat back into the room. These inexpensive boxes are available at any hardware store.

Earth Berms

Slope the earth up against the house to protect it from cold winters and hot summers. Called berms, these mounds use the high thermal mass of the earth to keep your building cool. Berms can be an attractive addition to your landscape.



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