Plants Modify Solar Radiation
And Save You Money

Trees and shrubs shade people and buildings from the direct rays of the sun. During winter, deciduous trees and shrubs shed their leaves and let the sun's rays help warm the house. This is an important consideration if you are planting for summer shade on the southern exposure of your house. Maples and other trees with full crowns are best for summer shading. The high branches permit greater visibility and do not block the flow of cooling breezes.

Evergreens have cone-shaped crowns which provide less shade on walls and roofs. Their branches often extend to the ground, blocking visibility and the flow of cooling breezes. If planted in the wrong location, they may shield your house from the sun's warmth in winter.

Trees provide maximum shade when planted in groups beside your house, however, a roof need not be totally shaded to achieve excellent results. A study in Alabama showed that air-conditioning costs could be reduced effectively as long as the amount of shade on the roof averaged 20 percent or more for the entire day.

Deciduous vines that cling to trellises along walls can afford protection on the south and west sides of a house. However, vines which cling directly to walls may cause some structural deterioration. By providing shade on walls, vines keep the surface temperature down and reduce convection-caused heat gain. Additional cooling comes from evaporation of moisture from the leaves. Evergreen vines such as English ivy should not be used on walls facing south since they block the winter sun's warming rays. Vines may help insulate walls on the north and west sides by curbing winter winds.

(Adapted from "Landscaping to Cut Fuel Costs," by Jerome R. Smith, Extension Housing Specialist (Retired)