Window awnings increase comfort, save on cooling bills
Q. We need to block the intense summer heat from coming through our home’s windows and door glass. We want to install awnings but are not sure what size or material to get. What do you recommend?
A. The sun shining in through windows and doors can quickly overheat a room. This is the same basic greenhouse effect that is warming the Earth. The sun’s short-wave-length heat energy easily passes through glass into your house. Once in there, the heat becomes longwave-length energy. Glass is relatively opaque to this, so the heat stays trapped indoors.
Closing curtains and drapes can help trap the sun’s warmth near the windows — but the heat has already gotten indoors through the glass.
In contrast, exterior awnings block the sun’s heat before it enters your house, so they are more effective for reducing air-conditioning costs. Studies have shown that awnings can reduce a room’s cooling needs by 24 percent in Boston, 21 percent in Phoenix and 17 percent in St. Louis.
From an energy-savings standpoint, the size of the awning is more important than the material. An awning should shade your window or door from the sun’s direct rays, especially during midafternoon, when it is hottest. Even though the sun is most intense and direct around noon, it is very high in the sky, so just the roof overhang is often enough to shade windows.
If you remember your high school trigonometry, it is possible to calculate the size (projection from the wall) needed for a fixed awning to effectively shade windows and doors.
The size depends upon the latitude of your area. If your location is farther north, the sun is lower in the sky, so a larger awning is needed. If you are not a math whiz, just make a test awning from cardboard to determine the proper size for a fixed awning. Fixed hood-type awnings with sides are a good choice because they increase the shading period throughout the day.
However, an adjustable awning is often the best choice because its projection can be changed with the seasons of the year and throughout the day, if needed. Keep in mind — you probably want the sun to shine in the window during winter to provide free solar heating. Adjustable awnings can be positioned high enough to allow the sun‘s rays to shine in, yet still provide protection from rain.
The two most common materials used for awnings are aluminum and fabric. Aluminum awnings are extremely durable, and unless they are damaged from an impact, they can last a lifetime. Fabric awnings are generally more attractive and offer more design, color and styling flexibility.
Another advantage of fabric awnings is that an adjustable one can be lowered almost flat against the window. This provides protection from harsh weather and driving rains.
Adjustable aluminum awnings typically cannot be lowered as far, but their strength provides excellent protection. The following companies offer window awnings: Awntech (800-200-5997, www. awntech.com), Craft-Bilt (800-422-8577, www.craftbilt.com), K. E. Durasol Awnings (888-387-2765, www.keoutdoor
design.us), Eastern Awning (800-4454142, www.easternawning.com) and
General Awnings (888-768-8404, www. generalawnings.com).
Q. I have always heard that you should keep a refrigerator and freezer reasonably full to make it operate most efficiently. How do I determine what “reasonably full” means?
A. Reasonably full means having the shelves of the refrigerator portion almost completely covered with a typical array of various-size containers, bottles and cans. It is important to allow space for air to circulate freely around inside the refrigerator portion.
Although the freezer portion also needs some airflow space, you can pack frozen foods in tighter. Keeping the freezer full also helps keep it cold if there is an extended power outage.
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