Smart Landscaping and Energy Efficiency
The temperature and comfort of your house is directly affected by your climate. Air temperature, ground temperature, the amount of sun that comes through your windows, air leaks around doors and windows -- all can make your house cooler or warmer than you'd like.
Smart landscaping can go a long way toward increasing the comfort of your home. Just a few simple considerations when landscaping your home and property can make a big difference in your comfort and the efficiency of your heating and cooling systems:
- Carefully positioned trees can reduce a household's energy consumption for heating and cooling by up to 25 percent. Computer models devised by the U.S. Department of Energy predict that the proper placement of only three trees can save an average household between $100 and $250 in energy costs annually.
- On average, a well designed landscape provides enough energy savings to return your initial investment in less than 8 years.
- Shading of an air conditioner can increase its efficiency by as much as 10 percent.
- A well-planned landscape can reduce an unshaded home's summer air-conditioning costs by 15 to 50 percent.
- In open areas, windbreaks to the north, west and east of houses cut fuel consumption by an average of 40 percent. Houses with windbreaks placed only on the windward side (the side from which the wind is coming) averaged 25 percent less fuel consumption than similar, unprotected homes.
- Give highest priority to planting shade trees due west of west windows. Planting shade trees due east of east windows should be your second priority. Select a tree that can be planted within twenty feet of the window and that will grow at least ten feet taller than the window. When space permits, use as many trees as needed to create a continuous planting along all major west- and east-facing windows.
- Contrary to intuition, the least energy efficient place for a tree is to the south of a house. In summer when the sun is high at midday, the shadow of a tree falls directly under the tree and entirely misses a home to its north. In winter, however, the shadow of the same tree will fall on the house throughout most of the day. To avoid shading south windows, any trees south of the home should be located at least twice their mature height away from the house.
- Any trees on the southwest or southeast sides of the home should be pruned as they grow to remove their lower branches to allow more winter sun through; however, lower branches on trees northwest of the home are desirable to create the most shade in late afternoon. Large deciduous trees very close to the south side of the building can have their lower branches removed to allow more sun to reach the building in winter.
- An air conditioner runs more efficiently if it is in a cooler environment. For instance, less air conditioning is necessary to cool a car if it was parked in the shade. Paved areas like driveways and patios absorb and radiate heat far faster than planted areas. Plant trees near paved areas around the house or grow vines on a trellis over or near patios to create cooler areas around your house. For good airflow and access, plants should be more than three feet away from the air conditioner.
- Evergreen trees and shrubs planted to the north and northwest of the home are the most common type of windbreak. Trees, bushes and shrubs often are planted together to block or impede wind from ground level to the treetops. Or, evergreen trees combined with a wall, fence or earth berm (natural or man-made walls or raised areas of soil) can deflect or lift the wind over the home. Be careful not to plant evergreens too close to your home's south side if you are counting on warmth from the winter sun. A windbreak will reduce wind speed for a distance of as much as 30 times the windbreak's height. For maximum protection, however, plant your windbreak at a distance from your home of two to five times the mature height of the trees.
- Planting shrubs, bushes, and vines next to your house creates dead spaces that insulate your home in both winter and summer. Plant so there will be at least one foot of space between full-grown plants and your home's wall.
To learn more about how you can use smart landscaping decisions to increase your energy efficiency, please visit the Department of Energy's website.
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