Sittin’ in the Shade

Depending on which way your windows face, exterior shading can be a very effective strategy for cooling the inside of your home. Individual exterior window shades have the advantage over interior shades because they block solar heat and glare before it reaches the window. Any heat absorbed by the shade itself stays outdoors – never impacting the interior of the house. Properly placed shade trees are also very effective at blocking heat and glare. Be sure to evaluate a tree’s “cooling” ability before cutting one down or planting.

Interior shades can also play a part in blocking solar heat, but choose carefully. Depending on their color and material, interior shades will absorb some amount of solar heat which becomes transferred back into the room. Cloth and wood shades will absorb less heat than aluminum. The outward (window) facing surface should be as light-colored as possible to reflect the most heat. White is ideal. Interior shades should also cover the window as completely as possible to form an “air pocket” between the window and shade. Trapping air in this manner keeps it from circulating inside the house, adding to the heat load.

The images below come from the Florida Solar Energy Center’s Homeowner’s Guide to Residential Window Selection. You can find more information about exterior shading as well as all other things solar.

This blog was written for Paul LaGrange’s BuildWrite website and was originally posted on September 5, 2009.

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