Forget AC! Cool Your Home Naturally

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Evaporative coolers. In the western United States where humidity levels are low, new designs for evaporative (swamp) coolers are a high-performance alternative to conventional air conditioning systems. They use less than one quarter as much energy as air conditioners, and don’t require toxic chlorofluorocarbons (CFCs) or other refrigerants. They cool the air by drawing warm outside air over a wet filter pad. The water then evaporates from the pad to reduce the air’s temperature. A fan circulates the moist, cool air into the room, and pushes warm air out through open windows. Small, room-sized units start at $100 and require no installation, while whole-house systems can cost from $2,000 to $4,000, including installation. Solar evaporative coolers powered by photovoltaic (PV) cells also are now available. The PV cells operate during peak hours of the day, when it’s hottest and electricity is most expensive.

Best Bets for Passive Cooling

According to Rocky Mountain Institute, passive cooling measures can reduce energy bills by up to 40 percent. In addition to natural ventilation, the most effective cooling strategies, in order of increasing cost, are:

• The minimization of indoor heat generation. For example, using energy-efficient light bulbs, reducing hot water use, using smaller and more efficient appliances and scheduling heat-producing tasks (such as clothes drying) for cooler hours of the day.
• Weatherization. Caulking, sealing and weatherstripping all building envelope seams, cracks and openings reduces heating and cooling energy requirements.
• Insulation. Insulating your home or installing heat-reflecting foil reduces heat conduction into your living space.
• Window shading and glazing. Solar radiation passing through windows can contribute 20 percent to heat gain in hot, humid climates. Window shading devices and glazing technology minimize heat gain while transmitting daylight, which reduces electrical lighting needs.
• Roof whitening and attic ventilation. These are two effective measures to reduce heat gain by either reflecting heat away from the roof or flushing heat out through the attic.
• Trees and landscaping. Planting broad, leafy shade trees that block the sun will reduce the amount of solar radiation absorbed by the house.

For more information, visit http://www.rmi.org/.

Natural Cooling Checklist

Low-hanging Fruit: Things You Can Do Today

• Experiment with your existing windows to improve airflow. If your house has casement windows, not only can you get the maximum ventilation area for a given glass area, but you also can use the windows to catch and direct airflow. For double-hung windows, you might want to try opening both sashes partway; this can let cooler air in at the bottom and warmer air out at the top. If you have operable transoms above doors and windows (interior or exterior), use them to exhaust hot air that collects near the ceiling; you might want to add transoms if you don’t already have them. If your house has more than one level, try opening high and low windows to pull air through the house vertically.
• Seal any cracks around the perimeter of your house.
• Tune in to the breeze. When it’s hot, anything that amplifies your awareness of the breeze can have a psychological cooling effect. Hang a wind chime or bell, or plant bamboo or another “rustley” plant in the path of summer breezes, and enjoy the feeling of wind amplification.

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