Tree Power.

Proper Landscaping Can Cut Utility Bills in Half

Believe it or not, landscaping may be the best long-term investment for reducing home heating and cooling costs. An asset to your yard and community, proper tree, shrub and grass plantings can protect your home from the ravaging onslaught of winter wind and snow, as well as summer's baking heat and urban noise, while reducing your utility bills by as much as 50 percent, says the U.S. Department of Energy's (DOE) Energy Efficiency and Renewable Energy Clearinghouse (EREC).

In fact, the DOE estimates that the proper placement of as few as three trees can save the average household between $100 and $250 annually in energy costs. Because trees and shrubs shade the ground and evapotranspire (release water vapor), air temperatures below trees can be as much as 25 degrees cooler than air above nearby blacktop, which helps reduce summer cooling needs. Planting deciduous trees (which lose their leaves in the fall) provides summer shading, while opening up your home to winter's solar rays.

Ken Sheinkopf, executive vice-president of the Solar Energy Research and Education Foundation, says there are three main considerations when landscaping for energy-efficiency: your house's orientation to the sun; the amount of shade you'll need; and the intensity and direction of wind around your home. Planting evergreen trees and shrubs north and northwest of a property is the most common type of windbreak, and can dramatically lower energy costs by channeling winds away from or over a house.

In addition to windbreaks (planted two to five times the mature height of the tree away from your home), planting shrubs, bushes and vines right next to a house also helps by creating "dead air spaces" that insulate your home both in summer and winter (one foot of space between plants and wall is ideal).

To decrease energy use in summer months, arrange plants to shade east and west walls, recommends Sheinkopf, making sure to provide cover for air conditioning units. If you live in a sweltering or arid climate, allowing summer breezes to enter your home will lower air conditioning costs, as winds carry away warm, humid air. To accomplish this, tree canopies need to be high enough to block downward solar radiation, but should have thin, unvegetated trunks to allow breezes through underneath.

EREC suggests that, before making any landscaping decisions, you should sketch your ideas first, drawing in deciduous and evergreen trees and shrubs, walls, fences, light and dark concrete, and any other formations that may alter radiation, sunlight, wind or snowfall. Draw arrows to show typical wind direction, sun angles and north/south orientation. Also keep in mind structures which may interfere with new plantings or their growth, such as utility poles and wires. With the help of landscapers, calculating your "solar window"--the amount of sun your house receives given its placement on the lot--will determine where to position yard plants to maximize energy-efficiency.

And though it may be hard to part with a current resident of the yard, EREC advises relocating or removing shrubs or trees that hinder proper wind channeling or solar exposure.

Areas not used as family or play areas can be "xeriscaped," or planned with low water use in mind, note the authors of Energy-Efficient and Environmental Landscaping (Appropriate Solutions Press). Native vegetation that's drought-resistant and relies mainly on rainfall is a great way to shrink that water bill. And converting a traditional lawn to short-growing grasses like buffalo grass can reduce local air and noise pollution and save time, by reducing lawn-mower use.

"Poor plant selection is the most common problem," says Mike Lamb, energy manager for EREC. Dense foliage makes a great wind blocker and sun filter, but can hinder summer breezes that cool indoor air or pose security risks near windows or doorways, cautions Joel Albizo of the American Nursery and Landscape Association. Homeowners also make the mistake of choosing plants inappropriate for some climates. Also be conscious of a tree's root system, which can damage sewer lines or sidewalks as it matures, says Lamb.

To aid in your decisions, rely on local landscape professionals, nurseries or county extension offices, advises Albizo. Professionals can point out costly mistakes before trees are in the ground, or provide additional design ideas. Find out how large each species will grow and plan your yard according to its mature growth, suggests EREC. And when you're ready to pick out plants and trees, make doubly sure they're native to the area and disease- and pest-free.

Vegetation offers the environmental plus of added erosion-control, improved air quality, and food and habitat for wildlife and birds. And according to Kiplinger's Personal Finance, a well-designed landscape can add from seven to 15 percent to the resale value of your home. CONTACT: EREC, PO Box 3048, Merrifield, VA 22116/(800)DOE-EREC.

TRACEY C. REMBERT is managing editor of E.