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Solar Energy Solar Home Design Guide
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Beating The Heat The simplest way to keep cool is to first design and build your home for our unique climate, but that's another article. For now we'll concentrate on cooling an existing home. If your goal is to keep a home cool in our desert climate, turning on the air conditioner or evaporative cooler is the LAST thing you should do. They're expensive to operate, they use water and they're noisy. There is no single answer to being comfortable but taking the shotgun approach is easier, and less expensive. The three major sources of unwanted heat in your house during the summer are heat that conducts through your walls and ceiling from the outside, heat that is given off inside your house by lights and appliances, and sunlight that shines through windows.
Keeping the sun out of your home is obviously a major goal. Closing curtains and drapes makes your home darker but doesn't effectively stop the heat. Stopping the sun's energy from entering your home is best done on the outside of the window. Solar screens or shade cloth can stop as much as 80% of the sun's heat before it enters your home. These materials are available at most home centers and window and screen suppliers. Windows on the west side are typically the biggest problem followed by the east and north facing windows. South facing windows are often protected by your roof overhang which shades the glass when the sun is at it's highest point. High-performance windows with "low-emissivity" coatings (Low-E) and low "shading coefficients" will stop heat from the sun while allowing visible light to pass through the glass. These same windows help keep heat on the home during the winter.
Landscaping can play a large role in achieving comfort. Trees located on the west, east and north can not only put windows in shade, but also shade the walls of the home as well as the ground area. This shaded area keeps the home cooler and cools breezes as the reach the home. On the south side, you should choose low growing shrubs and plants so as not to block the winter sun from entering south facing windows. This vegetation will reduce the amount of solar energy which is reflected into windows by lighter colors. The colors of various materials around your home can have a dramatic effect on your comfort and wallet. A dark colored roof can reach temperature 40 degrees hotter than a light colored reflective roof. This heat not only increases the cooling load of your home but also decreases the life of your shingles. Ventilate your attic space to reduce heat build-up during the summer which finds its way into your home. Darker colored walls, especially brick and stone will actually absorb solar energy which increases cooling problems and slows the night time cooling process. To reduce heat gains through walls and your ceiling, you can add insulation and seal up cracks to reduce air infiltration You can reduce heat from lights and appliances by purchasing energy-efficient products. A conventional, incandescent light bulb uses only 10% of its input energy to produce light and the other 90% is wasted heat. Compact Fluorescent lights can produce the same amount of light as an incandescent lamp but use about one-fifth the energy and produce about one-fifth the heat. Check out the EPA's Energy Star web site (www.energystar.gov) for energy smart options for your home. Natural ventilation by opening windows is only effective when outdoor temperatures are lower than interior temperatures. An indoor/outdoor thermometer is a useful tool to determine the optimum time to open your windows. Open your windows when this temperature difference is reached in the evening and then close your windows in the morning. Opening windows more on the downwind side will increase air flow.
Evaporative Cooling It's very important to supply fresh water to an evaporative cooler and flush out the salts etc. left behind in the evaporation process. Typically this is accomplished with a bleed-off line but there is a better, water saving method available at most home centers. Sometimes referred to as a "power dump" this new pump is installed in addition to your regular pump. This new pump operates on a timer and is designed to flush all the water in the pan once every 8 to 12 hours of operation.
The more attention you pay to the sun's impact and the way you operate your home, the less you'll spend while being more comfortable. |
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