Energy-efficient landscaping

Smart tree placement can lower your electric bill and increase comfort year-round
By James Dulley
Energy-efficient landscaping

The deciduous trees on the south side of the home allow the sun’s heat through during winter. Evergreens are located to the northeast.

Smart landscaping can do more than just create an attractive yard. It can also lower your utility bills, summer and winter, and improve your family's comfort year-round.

Trees are critical components to a good plan. The primary goal of efficient landscaping with trees is to shade your home during summer, yet allow the sun to pass through during winter. Additional goals are, depending upon your climate, to allow cool evening breezes to flow around your house and to provide moisture for evaporative cooling of air near your house.

Efficient-Landscaping-Diagram-James-Dulley

A typical efficient tree landscaping plan for a temperate climate, with concerns for summer cooling and winter heating. Note the evergreen windbreak to the north and northwest sides.

Ground-Cover-James-Dulley

Ground cover plants and boulders are shaded by trees during the summer and the rocks help warm the home during winter.

In most North Carolina locations, a typical efficient tree landscaping plan has deciduous trees to the south, southeast and southwest. The leaves block the sun during summer, but when the leaves fall, the sun shines through to heat your home. Leave a small gap to the southwest to allow cooler evening breezes to flow through.

Plant dense evergreens along the north, northeast and northwest sides, which block cold winter winds. With shorter days and the sun lower in the sky during winter, not much solar heat comes from these directions.

In hot, humid weather, shading during summer is most important. Taller trees closer to your home can block the sun, which is higher in the sky.

Alternatives to grass include ground cover plants and gravel. Low-growing ground cover near your house can help to keep it cool during summer. The leaves block the sun's heat from absorbing into the ground, and they give off moisture for natural cooling. The additional moisture from plants near the house, however, can increase the relative humidity level. This is more of a problem if you rely on natural ventilation than when air-conditioning with the windows closed.

Landscaping with gravel eliminates the need to water grass, but it can raise the air temperature around your house, particularly in the evening. This helps in the winter, but you may want gravel shaded by deciduous trees during the summer.

A good location for ground cover is between an asphalt or cement driveway (or walkway) and the sunny side of your house. A hot driveway can radiate heat up to your house. Planting taller ground cover between it and house walls can block some of this heat.

About the Author

James Dulley is an engineer and syndicated columnist for the National Rural Electric Cooperative Association. www.dulley.com

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