Fact or Fable? Trees Can Lower Your Energy Bill by 30 Percent
This is a fable...sort of. Planting trees may not reduce your total utility bill by 30 percent, but it can provide substantial savings when it comes to heating and cooling costs.
Leafy trees planted on the south and west sides of homes or buildings provide shade that blocks the sun on hot summer days; cooling the interior and reducing the need for air-conditioning. Dense evergreen trees planted on the north and northwest sides help to reduce the force of the wind; limiting the amount of outside air that enters the home.
Carefully positioned trees reduce energy use for heating and cooling by up to 25 percent, according to the U.S. Department of Energy (DOE). A well-planned landscape can reduce a home’s summer cooling costs by 15 to 50 percent, according to a study by the DOE's Lawrence Berkeley National Laboratory. A South Dakota study found that houses with windbreaks placed on the windward side reduced heating energy use by 25 percent, compared to unprotected homes. Trees also provide an environmental benefit: for every acre of trees, up to 2.6 tons of carbon dioxide is removed each year.
The placement of trees is important for maximizing their effectiveness. Place trees 15 to 20 feet from the house to get the most useful shade. Small trees may be planted closer than 15 feet, but large trees should be planted 20 feet, or more, from the house. Windbreaks will reduce wind speed for a distance of as much as 30 times their height. For maximum protection, plant your windbreak a distance from your house of two to five times the height of mature trees.
The amount of savings from planting trees varies significantly, depending on building orientation and the local climate. However, it is clear that carefully placed trees not only add beauty to your surroundings—and can improve home values—they will help to trim your annual energy bills as well.
See Landscaping from the U.S. Department of Energy for more information about how a well-designed landscape can save you money.