Shade: nature’s own (almost free) energy saver
by Ron Rothenberg, 4 Buyers Real Estate
“Awnings can directly affect energy use by simply blocking the sun. heat gain through windows is one of the main reasons why buildings need air conditioners… In some climates you can save 20 to 25% of your cooling energy just by using awnings.” –John Carmody, Director, Center for Sustainable Building Research, University of Minnesota
When I was a boy in the 1960s, I can remember how swiftly each Springtime would transform most of the houses on my street: the snows would recede, the trees and bushes would fill in, and awnings would appear in front of many windows.
Each Spring we’d go through the awning ordeal: go up to the attic, get the heavy canvas awnings and their metal frames down. We’d take them out in the yard and wash them, pass them out the window and secure them to their posts, run the ropes through the grommets. We’d check to see that the vents were clear, so the awnings wouldn’t overheat.
In exchange for all that one-time work, you’d get a much cooler, shadier house all summer, without using air conditioning. If we had air conditioning, we would have saved a fortune on it.
Ironically, during the 1980’s when there were high tax credits for high-tech energy saving methods, people started to ignore the awnings. People started replacing their old windows and being concerned about solar-heat gain and heat loss through the windows, but they forgot how much more effectively your windows can lower your heating and cooling bill in tandem with low-tech awnings.
According to the Center for Sustainable Building Research at the University of Minnesota an awning can reduce solar gain (that’s heat added to the inside of your house by the sun) by 77% on west-facing windows, and up to 65% on south-facing windows. In the winter, when you want the solar heat, you just take those awnings off or roll them up.
The savings from awnings occur during peak usage hours, so you can get by with a smaller air conditioner than you would need otherwise. From a societal standpoint, utilities could get by with fewer and smaller generating plants if everyone would use awnings.
According to the report by the Center for Sustainable Building Research, the further north you go, the more energy can be saved by awnings. For a home in the Boston area, according to the Center’s tests, it took 855 kWh to cool their test houses without awnings. With awnings it took only 651 kWh to cool a house with approximately equal window orientation. For houses with mostly south and west facing windows the savings was more dramatic: it took 965 kWh to cool the house without awnings, 677 kWh to cool the house with awnings. That’s a 30% savings. You can reduce peak demand in a house with a mostly westward window orientation by as much as 40%.
You can read a summary of the report at:
or the entire report at:
When you’re thinking about new windows, or just trying to improve the energy performance of your old windows, consider getting attractive awnings for your home. They’ll improve the energy efficiency of your home far more than just new windows alone.