Natural Cooling

Blocking the Heat

The following are passive methods for blocking unwanted heat energy from your home.

1. Low ground cover such as grass, small plants, and bushes can also be very effective in cooling. A grass-covered lawn is usually 10 degrees F (6 degrees C) cooler than bare ground in the summer. If you are in an arid or semiarid climate, consider native ground covers that require little water.
2. Deciduous trees that lose their leaves in the fall help cut cooling energy costs the most. When selectively placed around a house, they provide excellent protection from the summer sun and permit winter sunlight to reach and warm your house. The height, growth rate, branch spread, and shape are all factors to consider in choosing a tree. Vines are a quick way to provide shading and cooling. Grown on trellises, vines can shade windows or the whole side of a house.
3. Solar screens resemble standard window screens except they keep direct sunlight from entering the window, cut glare, and block light without blocking the view or eliminating air flow. They also provide privacy by restricting the view of the interior from outside your house. Solar screens come in a variety of colors and screening materials to compliment any home. Although do-it-yourself kits are available, these screens will not last as long as professionally built screens.
4. The attic is a good place to start insulating because it is a major source of heat gain. Adequately insulating the attic protects the upper floors of a house. Recommended attic insulation levels depend on where you live and the type of heating system you use. For most climates, you want a minimum of R-30. In climates with extremely cold winters, you may want as much as R-49.
5. Weatherization measures such as insulating, weather-stripping, and caulking help seal and protect your house against the summer heat, in addition to keeping out the winter cold. Although unintentional infiltration of outside air is not a major contributor to inside temperature, it is still a good idea to keep it out. Outside air can infiltrate your home around poorly sealed doors, windows, electrical outlets, and trough openings in foundations and exterior walls.
6. Draperies and curtains made of tightly woven, light-colored, opaque fabrics reflect more of the sun's rays then they let through. The tighter the curtain is against the wall around the window, the better it will prevent heat gain. Two layers of draperies improve the effectiveness of the draperies' insulation when it is either hot or cold outside.
7. Landscaping is a natural and beautiful way to shade your home and block the sun. A well-placed tree, bush or vine can deliver effective shade and add to the aesthetic value of your property. When designing the landscaping, use of plants that are native to the local area survive with minimal care.
8. Shutters are movable wooden or metal coverings that, when closed, keep sunlight out. Shutters are either solid or slatted with fixed or adjustable slats. Besides reducing heat gain, they can provide privacy and security. Some shutters help insulate windows when it is cold outside.
9. Awnings are very effective because they block direct sunlight. They are usually made of fabric or metal and are attached above the window and extend down and out. A properly installed awning can reduce heat gain up to 65 percent on southern windows and 77 percent on eastern windows. A light-colored awning does double duty by also reflecting sunlight.
10. Wall insulation is not as important for cooling as attic insulation because outdoor temperatures are not as hot as attic temperatures. Also, floor insulation has little or no effect on cooling.
11. Venetian blinds, although not as effective as draperies, can be adjusted to let in some light and air while reflecting the sun's heat. Some newer blinds are coated with reflective finishes. To be effective, the reflective surfaces must face the outdoors.
12. Besides providing shade, trees and vines create a cool microclimate that dramatically reduces the temperature (by as much as 9 degrees F [5 degrees C]) in the surrounding area. During photosynthesis, large amounts of water vapor escape through the leaves, cooling the passing air. And the generally dark and coarse leaves absorb solar radiation.