Conservation Through Landscaping
Significant cash savings can be realized by properly using trees for shade. How much is saved depends on existing tree cover and the type of home. However, savings of 58 percent of daytime air conditioning have been documented. Ten percent savings are more common but even this amount is no small matter in most budgets. What to shade?
Maximum benefit from shade usually comes from trees on the east and west sides of a building, and close to the walls. A 25-foot tree 10 feet from the west wall may shade 47 percent of the surface in mid-afternoon compared with only 27 percent if planted 20 feet from the wall. - Prioritize areas of greatest heat gain or importance for comfort.
- Dark or rough-textured surfaces absorb more heat than light-colored or smooth surfaces.
- Provide shade for "heat sinks" like driveways and patios.
- Shading an air conditioning unit can increase its efficiency by 10 percent.
- Plant trees and shrubs to shade windows. About three-fourths of total solar heat gain in a building comes through windows.
- Plant trees with strong wood. Fast-growing species with weaker wood (like willows and silver maple) may be useful for quick shade. Stronger, slower-growing trees that are shade tolerant may be interplanted among or next to them. When the slower trees reach a useful height, the weak ones should be removed.
- Plant groups of trees to intensify shade and reduce lawn area.
- In areas close to busy streets, trees can help muffle noise, provide visual screens and contribute to surrounding property values. They also reduce or slow surface run-off of water.
Relative shade value of deciduous trees
Leaf density and branching characteristics combine to determine the amount of solar radiation that can penetrate the canopy of a tree. The less penetration, the higher a tree's shade value. Highest: Maples, horse-chestnut, hackberry, beech, green ash, walnut, yellow popular, sycamores. Medium: European birch, crabapple, sweetgum, oaks, littleleaf linden, Kentucky coffeetree, cottonwoods, elms. Lower: Hickories, catalpa, ginkgo, locusts, goldenrain tree, quaking aspen, pears, Washington hawthorn.
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