Reduce utility bills with shade trees

Richard Bogren, Gill, Daniel J.

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For Release On Or After 07/02/10

By Dan Gill,
LSU AgCenter Horticulturist

When you think of shade trees in your landscape, you most likely focus on the shade they create outside. It would be hard to do anything on a patio or deck this time of the year unless it was shaded. But trees that shade our homes also help hold down inside temperatures far better than curtains or blinds. And this lowers the cost of summer air conditioning.

Shade lowers air-conditioning bills by blocking the sun from the windows, exterior walls and roof. Air conditioners cooling a fully shaded house have been shown to work only half as much as those in a house with its walls and roof exposed to the sun. Other research reports show shade trees will reduce heat gains by 40 percent to 80 percent, depending upon their placement and density. Even a sparse shade tree may be a better energy saver than an interior curtain.

Deciduous trees – those that drop their leaves during the winter – are generally the best choice. These trees let the sun shine on the house in the winter when the sun’s added warmth is welcome and provide shade during the summer when it is needed. Evergreen trees, which retain their foliage in the winter, provide constant shade, which is generally not desirable during cold weather. Evergreen trees do, however, provide good windbreaks for winter winds when planted on the north side of a house.

Proper shade tree location will help reduce energy consumption. Trees should be planted on the southwestern and western side of the house to be most effective. Trees in those locations will shade the house from the most intense sun during the hottest part of the day. Planting trees to the south and east also will help shade the house.

This doesn’t mean that you should completely surround your home in a forest of trees. People frequently plant too many trees on their property, not realizing how large they will become. Choose trees that will not grow too large for your property, and be aware that one or two major shade trees may be all your property needs.

Trees also need to be planted the proper distance from the house and away from concrete surfaced areas. Although house slabs are generally not affected, thinner concrete surfaces, such as patios, sidewalks and driveways, can be damaged by roots from trees planted too close. The recommended distances are generally related to the mature size of the tree. Larger trees, such as oaks, should be planted farther away from sidewalks, driveways and the house (at least 15 feet) than smaller trees like crape myrtles or yaupon hollies.

In addition to your home, you may have other areas where shade is necessary or desirable. Outdoor living areas are unusable in the Louisiana summer without some sort of shade, which properly placed trees could provide. Choose small-growing trees for planting close to patios because they are more in scale with the location and are less likely to damage surfacing materials.

When landscaping for energy conservation, deciding on the right placement and the number and type of trees requires careful planning, but you have plenty of time to think about it. Although now is the time to make decisions on where shade is needed and where to plant a tree, don’t forget the ideal tree-planting season in Louisiana is November through February.

Rick Bogren

1/4/2011 1:10:34 AM
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