Reduce utility bills with shade trees

Richard Bogren  |  7/21/2016 2:25:52 PM

By Dan Gill

LSU AgCenter Horticulturist

(07/22/16) 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.

Trees that shade the house during summer lower air conditioning bills by blocking the sun from windows, exterior walls and roofs. Air conditioners cooling a fully shaded house have been shown to work only half as much as those in a house that has its walls and roof exposed to the sun. Other research reports show that shade trees can 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 winter – are generally the best choice. These trees let the sun shine on the house in winter when the sun’s added warmth is welcome and provide shade during summer when it is needed. Evergreen trees, which retain their foliage year-round, provide constant shade, which generally is not desirable when weather is cold. Evergreen trees do, however, provide good windbreaks for winter winds when planted on the north side of the house.

The location of your shade trees is important to how well they help reduce energy consumption. Trees should be planted on the southwestern and western sides 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. Of course, trees on the south and east sides will help shade the house, too.

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 later on. 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 houses (at least 15 feet) than smaller trees like crape myrtles or yaupon hollies.

In addition to your home, decide on other areas where shade is necessary or desirable. Outdoor living areas are often unusable in the Louisiana summer without some sort of shade that 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, 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 the trees, don’t forget the ideal tree-planting season in Louisiana is November through February.

Gardening in the Heat

Speaking of dealing with high temperatures, weekend gardeners are often more accustomed to air-conditioned homes and workplaces than the outside heat. We are now in the hottest part of our summer season. Each year about this time I make it a point to caution gardeners about working in the heat. High temperatures combined with exceptionally high humidity make summer conditions difficult to endure when working outside. The most stressful time of the year for us and our gardens runs from June through September, and it does take its toll on us as well as our plants.

Gardening outside in especially hot weather places extra stresses on the body. As the body sweats, it dehydrates. This can cause headaches, weakness and nausea and sometimes even lead to heat stroke. Gardeners working outside in hot weather may lose up to 2 quarts of water each hour.

To prevent dehydration, drink before, during and after working outside. It is especially important for the body to have a good storehouse of fluids well before the start of outdoor gardening activities. Drink before you’re thirsty and drink cold liquids because they are absorbed by the body more quickly. Drink water or sports drinks. If you choose other liquids, make sure they contain only a small amount of sugar, which slows down liquid absorption by the body. Avoid beverages containing alcohol or caffeine.

Work in your garden in the early morning or late afternoon when temperatures are cooler and stay in shady areas as much as possible. Follow the shade in your landscape as the sun moves across the sky; leave areas as they become sunny and move into areas as they become more shaded. Wear a hat and loose, comfortable clothing and use sunscreen. Also, take frequent breaks and try not to stay out in the heat for extended periods.

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Trees planted on the southwestern and western sides of the house will shade the house from the most intense sun during the hottest part of the day. Photo by Rick Bogren

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