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Landscaping for Energy Efficiency

Strategic tree planting can lead to ideal shade and wind blocks

The approach of spring has many gardeners turning their attention to planting plans, but if energy efficiency is one of your goals as a homeowner, you should know that landscaping can beautify your home while helping you control energy costs for years to come.

According to researchers at the Department of Energy’s National Renewable Energy Laboratory, carefully positioned trees can save a household as much as 25% on its heating and cooling costs. Foundation shrub plantings can also help control energy costs by diffusing solar heating or wind to moderate temperature transfers.

No matter how much you love trees, give them some room. Don’t plant too close to foundations, pavement or plumbing because root systems and maturing branches can damage foundations, roofs and pipes. And always make sure trees will be well clear of power lines when they reach their full size.

But planted in the right place, within five to 10 years, a fast-growing shade tree can reduce outside air temperatures near walls and roofs by as much as 6 degrees on sunny days. Surface temperatures immediately under the canopy of a mature shade tree can be up to 25 degrees cooler than surrounding shingles or siding exposed to direct sunlight.

According to the Department of Energy, deciduous trees—those that lose their leaves in autumn—are great options for summer shade. Tall varieties planted to the south of a home can help diffuse sunlight, providing shade for the roof.

Shorter varieties of deciduous trees can be planted near exposed west-facing windows to help shade homes on sultry summer afternoons. Mass plantings of evergreens—selected for their adaptability to regional growing conditions—can be planted farther away, on a north or northwestern section of a yard to form a windbreak, which helps shield a home from frigid winter winds.

Deciduous trees with high, spreading crowns (i.e., leaves and branches) can be planted to the south of your home to provide maximum summertime roof shading. Trees with crowns lower to the ground are more appropriate to the west, where shade is needed from lower, afternoon sun angles. Trees should not be planted on the southern sides of solar-heated homes in cold climates because the branches of these deciduous trees will block some winter sun.

Trees are available in appropriate sizes, densities and shapes for almost any shade application. To block solar heat in the summer but let much of it in during the winter, use deciduous trees. To provide continuous shade or to block heavy winds, use dense evergreen trees or shrubs.

Although a slow-growing tree may require many years of growth before it shades your roof, it will generally live longer than a fast-growing tree. And because slow-growing trees often have deeper roots and stronger branches, they are less prone to breakage by windstorms or heavy snow.

Trees, shrubs and ground cover plants can also shade the ground and pavement around a home. This cover reduces heat radiation and cools the air before it reaches your home’s walls and windows. Use a large bush or row of shrubs to shade a patio or driveway. Plant a hedge to shade a sidewalk. Build a trellis for climbing vines to shade a patio area.

To ensure the durability of energy-saving landscaping, use plant species that are adapted to the local climate. Native species are best, as they require little maintenance once established and sidestep the dangers of invasive species.