Landscaping is a natural and beautiful way to keep your home more comfortable and reduce your energy bills. In addition to adding aesthetic value and environmental quality to your home, a well-placed tree, shrub, or vine can deliver effective shade, act as a windbreak, and reduce overall energy bills.
Carefully positioned trees can save up to 25% of a typical household's energy for heating and cooling. Computer models from DOE predict that just three trees, properly placed around the house, can save an average household between $100 and $250 in heating and cooling energy costs annually.
During the summer months, the most effective way to keep your home cool is to prevent the heat from building up in the first place. A primary source of heat buildup is sunlight absorbed by your home's roof, walls, and windows. Dark-colored home exteriors absorb 70% to 90% of the radiant energy from the sun that strikes the home's surfaces.
Some of this absorbed energy is then transferred into your home by way of conduction, resulting in heat gain inside the house. In contrast, light-colored surfaces effectively reflect most of the heat away from your home. Landscaping can also help block and absorb the sun's energy to help decrease heat buildup in your home by providing shade and evaporative cooling.
Shading and evaporative cooling from trees can reduce the air temperature around your home. Studies conducted by the Lawrence Berkeley National Laboratory found summer daytime air temperatures to be 3° to 6°F cooler in tree-shaded neighborhoods than in treeless areas. The energy-conserving landscape strategies you should use for your home depend on the type of climate in which you live.
Buildings and Trees – Natural Partners
• Trees that lose their leaves in the fall (i.e., deciduous) are the most effective at reducing heating and cooling energy costs. When selectively placed around a house, they provide excellent protection from the summer sun but 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 provide shading and cooling. Grown on trellises, vines can shade windows or the whole side of a house.
• Deflect winter winds by planting evergreen trees and shrubs on the north and west sides of your house; deflect summer winds by planting on the south and west sides of your house.
Orientation of the house and surrounding landscaping has a large effect on energy consumption. A well-oriented, well-designed home admits low-angle winter sun to reduce heating bills; rejects overhead summer sun to reduce cooling bills; and minimizes the chill effect of winter winds.
Fences, walls, other nearby buildings, and rows of trees or shrubs block or channel the wind. Bodies of water moderate temperature but increase humidity and produce glare. Trees provide shade, windbreaks, and wind channels. Pavement reflects or absorbs heat, depending on whether it is light or dark in color.
Just as wearing white clothes reflects the sun's heat from your body, a white or light-colored roof will help reflect the sun's heat away from your home. This strategy works particularly well when trees are located next to the reflecting surface. Not only does the tree provide shade, it absorbs the reflected sunlight for photosynthesis. In the process, water evaporates from the tree, cooling the air around the house.
Contact your county extension agents, public libraries, local nurseries, landscape architects, landscape contractors, and state and local energy offices for additional information on energy-efficient landscaping and regional plants and their maintenance requirements.
For more information on landscaping for energy efficiency, contact:
American Society of Landscape Architects (ASLA),
National Arbor Day Foundation (NADF),
U.S. Department of Agriculture,
County Extension Service - Local Chapter
U.S. Department of Energy's
Energy Efficiency and Renewable Energy Clearinghouse (EREC), (800) DOE-EREC (363-3732), and Network (EREN).