April 4, 2002

Planting Trees Can Ease Energy Consumption

With the area’s planting season approaching, those planning landscapes should keep in mind that strategically placed trees and shrubs near buildings may be the best long-term investment for reducing home heating and cooling costs, says Ron Smith, extension horticulturist at North Dakota State University.

"The small initial cost of planting trees and shrubs provides a long-term investment that will continually reduce energy and fuel consumption," Smith says. "In addition, a well-designed landscape can add 7 to 15 percent to the retail value of the home."

Plants reduce energy needs through shading and by release of water vapor as plants absorb heat.

Smith says groves of trees can reduce or replace the need for air conditioning. The air temperature below trees can be as much as 20 degrees cooler than air above nearby pavement or exposed rooftops. U.S. Department of Energy research has shown that proper placement of trees and shrubs can reduce energy needs by as much as 50 percent.

Planting trees where they will offer the maximum shade in summer and minimum shade in winter is what’s needed, says Smith. Twice as much solar heat enters the house through west-facing and east-facing windows, so shade trees on the east and west sides of the home should be the highest priority, he says.

"These trees should block the summer sun during mornings and afternoons, but not during the winter months when sunlight is desired to warm the interior of the house. Deciduous shade trees, not evergreens, work best to achieve this because they drop their leaves in the fall," Smith says.

Examples of trees that develop a broad canopy that provides shade from summer sun include green ash, Kentucky coffee trees, Ohio buckeyes, lindens, river birches and honey locusts. All of these trees can be planted within 20 to 25 feet of windows and will grow at least 10 feet taller than the windows, he says.

Smith advises against planting tree species known for fast growth and weak growth near the house. These include boxelder maples, Lombardy poplars, weeping willows, cottonwoods and seedling silver maples. These are messy trees have a high production of dead wood, seed production and easily split branch connections.

For information about trees to consider around property, contact the local NDSU Extension Service county office and request NDSU publications F-436, A Guide to Deciduous Tree Knowledge, H-1104, Power Line Compatible Tree and Shrub Selections, and EB-38, Trees and Shrubs of North Dakota.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu