Landscaping for Energy Efficiency
by Dan Eskelson on May 2, 2012
The proper placement of trees and shrubs around a home will have a significant impact on the energy required to heat and cool the structure. The few simple strategies outlined below will not only increase the property value of your home but also decrease energy costs. Techniques will vary slightly from region to region, but with knowledge of local conditions and some common sense, the immediate environment can be maximized for energy efficiency.
Planting shade trees to the south of your home is one of the most obvious energy-saving techniques; deciduous trees will block the hot summer sun but allow the winter sun to reach the house. In some areas, planting a deciduous shade tree to the southwest or west may be desired.
The U.S. Department of Energy estimates that the proper placement of only three trees will save the average household between $100 and $250 in annual energy costs. Be sure to account for the mature size of the tree - a common mistake is to plant too close to the house. Evergreen trees are useful as a winter windbreak; a double or staggered row of dense evergreens on the windward side of the home can save an average of 25% of energy costs, even more in windy areas. A South Dakota study found that windbreaks to the north, west, and east saved an average of 40% in fuel consumption. This technique is even more effective when smaller evergreens are included on both sides of the larger trees.
Plant your windbreak at a distance from your home equal to three to five times the height of the mature trees. Choose plant material that is appropriate for your region. To the south of your home, shade trees with high spreading crowns like oak, maple, and ash are best to block the summer sun. To the west, trees with lower crowns, or evergreens, can be used to shade the hot afternoon sun. Avoid the fast-growing trees like willow, poplar, and silver maple - these are short-lived and brittle. Smaller plants can also help reduce energy costs.
Vines are quick growing and will shade a south or west wall in one or two seasons. Vines can also be grown on a strategically placed trellis or on a pergola that covers the entire patio area. Shrubs planted near the house will help to shield from the cold wind of winter and the hot sun of summer. In very damp climates, however, keep plantings at a sufficient distance from the house to ensure adequate air circulation.
Groupings of shrubs can be used to "funnel" cool, nighttime breezes to open windows. If the incoming air is from low vents or screened windows and the outgoing air leaves the structure at a higher point, this "chimney effect" moves a lot of air and does an excellent cooling job. If you're in an area that cools off in the evening, give this a try. When designing your new landscape, or adding to the existing, keep in mind that each region and each site has unique characteristics that must be considered to maximize energy efficiency. Study these characteristics in all seasons. For advice specific to your region, you might find some help at your County Extension Office.
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