4 Green Strategies for Keeping Cool

• Keep It Out. Thick or insulated walls, shade trees, deep eaves, and window awnings are all useful for making sure that conducted heat doesn’t make it indoors. Most of the sun is going to be hitting your roof, so it is particularly important to make sure your roof is both heavily insulated and highly reflective.
  • Install a radiant barrier–-an aluminized sheet fastened to the inside of your rafters–as an additional heat-reflector. Landscaping that shades your house in the summer is extremely advantageous.
  • Install insulated window shades or shutters on the sunny sides of your house, to keep both radiated and conducted heat from coming in your windows. Make it a daily summer habit to close both your windows and your shades in the morning and open them again at night as soon as it cools off.
  • Curtail activities that generate heat inside your house. In hot areas of the U.S., outdoor kitchens for summer use were once standard; perhaps that idea’s time has come again. At least use a microwave instead of an oven. Use a ventilator fan to remove bathroom heat after showering, and if you must use hot appliances such as a dishwasher or a hair dryer, try to do it at night.

• Move It Through.

  Many hot climates have weather patterns that can be used to cool your home. Many coastal areas for example, have a predictable onshore sea breeze. Funnel that breeze into your house, and it will flush heat out of it on the other side. Planting a hedge or a row of trees in a strategic place can help funnel cooling winds into your house.

  Dry climates, especially, tend to have distinct temperature drops at night. That’s when you should open your lowest windows and your highest, creating a convection “chimney effect” that sucks cool air into the lower part of your house from the outdoors while heat escapes up and out through the upper story, effectively cooling your entire domicile. Clerestories and operable skylights are excellent for increasing this effect. Attic vents are also a basic to convection cooling.

  If your natural ventilation needs a boost, use circulating fans. Ceiling fans circulate the air of an entire room, and there are fans for every size job. While they work best with high ceilings, proper placement can greatly enhance the effectiveness of fans at any height.

  • Window fans should be placed on the side away from prevailing winds, and in an upper window, to assist in exhausting hot air from your house.
  • Buy fans with Energy Star labels, they are about 20% more efficient than average.

  Attic fans exhaust air from the very hottest and highest part of the house, providing substantial heat relief through convection. This is a good place for a solar powered fan, powered by photovoltaic cells on your roof. Because they run fastest when the sun is hottest, they’re ideal for this application. If you live in a climate with many cloudy hot days, however, you should provide grid-powered back-up.

  A whole house fan is a workable substitute for air conditioning in most climates. Sometimes existing central heating and cooling ducts can be used with a whole house fan. These fans need to be appropriately sized, require dedicated wiring and, usually, an enlarged venting system in the attic. Unlike other fans, they are therefore typically professionally installed. The Department of Energy’s Consumer Guide has a good overview of whole-house ventilation systems.

• Wet It Down.

  In low-humidity climates it is much easier to solve the heat problem: just get wet. Evaporation is cooling; that’s the principle of perspiration. Evaporative coolers, also known as swamp coolers, use this principle too. They are simple machines that cost about half as much to install as air conditioning, use a quarter the electricity, and do not need ozone-depleting refrigerants to work. However, they need monthly (though easy) maintenance during peak use, and they only work well in dry climates.

  Swamp coolers have a small motor that pumps water from the bottom of the cooler to the top, where it falls down the sides of absorbent pads. Another motor runs a fan pulling outdoor air through the pads, cooling it 15 to 40 degrees F, and then into your home. Unlike air conditioning systems, coolers provide a constant flow of fresh outdoor air. They can be installed on roofs or on the ground floor (which makes maintenance easier). There are whole-house and room-sized coolers available. Newer, more efficient two-stage or indirect evaporative coolers incorporate a secondary heat exchanger to reduce the humidity released into the house. Read more about evaporative coolers at ToolBase Services to learn more about evaporative coolers.

• Use the Night.

  Where night temperatures drop substantially, nocturnal radiative cooling is particularly effective. Opening your windows at night, as mentioned above, is one component. The other requires some thermal mass in the building, such as a concrete slab floor, plaster walls, or passive solar water walls. These serve as heat sinks during the day, keeping the house cool. At night they release their heat as cool air passes over them.