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YARD AND GARDEN

Landscaping for energy conservation

David Robson

Most of us plant trees and shrubs because "they are pretty." Fall color may run the gamut from yellow to orange to red to purple. Sometimes the colors are intense, sometime they are muted.

Flowers can perfume the air, seemingly for miles. Fruits can attract birds and other wildlife to the yard.

Few people realize that plants can save you money on energy bills.

In the olden days, just about every farmstead had a windbreak of spruces, pines and firs that would funnel the north winter wind up and over the buildings, keeping down heating bills and snowdrifts. With fewer and fewer farms, and the valuable production land that the trees stand on, many windbreaks ended up in a burn pile.

The U.S. Department of Energy has generated some statistics dealing with energy and the home. My comments are in parentheses.

• Properly placed trees can save up to 25 percent of the household energy bill. (Deciduous trees planted on the south and west side of the house can reduce air conditioning bills by shading the house during the summer, but allow the sun to warm the building during the winter months.)

• Proper placement of only three trees can save the average household between $100 and $250 in annual energy costs. (Trees should be placed at least 14 feet from the house. Allow no less than 15 to 20 feet between trees, unless they are clumped together.

• Hardwood trees are better than those trees that grow eight feet in one year. Fast growing trees may provide quick shade, but the weaker wood means more wind, snow and ice damage. Make sure your trees aren't too large for the house. A bur oak probably won't cut the utility bills that much on a single story house. A red maple would be a better choice.)

• Shading an air conditioner unit can increase its efficiency by 10 percent. (Make sure you don't put a plant so close to the machine that air circulation is reduced. Keep plants at least six to eight feet away. Remember to clean out the leaves that filter through the air conditioner screen.)

• Shading and evapotranspiration can reduce air temperatures as much as nine degrees F. Because cooler air settles, the area under a tree may be as much as 25 degrees cooler than temperature above a nearby black-top. (Evapotranspiration is water loss from the leaves. The hotter and drier the air, the more water loss from the leaves. Make sure the soil is moist to take maximum benefit from the tree. Roots can get lots of water out of the soil, but if you water the trees every other week throughout the summer, plants will respond.)

• Tree-shaded neighborhoods may be as much as six degrees cooler than treeless ones.

• A well-landscaped yard can save 15 to 50 percent over an unshaded home. A Pennsylvania study found that 75 percent could be saved for a small mobile home. (Landscaping is more than just trees. It's the placement of shrubs and other plants around the house to provide shading. Evergreens around the foundation can help. Vines can also provide some great shading, especially in areas where planting trees may be difficult. Morning glory vines grow extremely fast, especially if started indoors, and can help cut down on summer's utility bills where trees aren't mature or acceptable.)

• The National Academy of Sciences estimates that there are 100 million potential tree planting sites in urban areas. If trees were planted in these areas, we could realize close to 25 percent savings on the total energy bill for air conditioners. This would cut down carbon dioxide emissions by 35 million tons and save more than $3.5 billion annually.

Planting trees and shrubs does more than just beautify an area, though there is nothing wrong with a prettier landscape. As one whose turfgrass is constantly being reduced, as more and more trees and shrubs are planted, I can tell you winter winds don't blow through the house as often, snow piles up in different locations, and I can leave the windows open during the summer and not worry about excess heat.

Think about planting trees in the spring and fall.

David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension. You can write to Robson in care of Illinois Country Living, PO. Box 3787, Springfield, IL 62708. Telephone: (217) 782-6515.
E-Mail: robsond@mail.aces.uiuc.edu

16 ILLINOIS COUNTRY LIVING MAY 2000