Trees and Shrubs

Shaded trees are beneficial in reducing direct sunlight reflections. They are necessary when it comes to energy efficiency. Keeping the environment cool, reduces energy spent on air conditional in both commercial and residential buildings.
Large trees and shrubs grows normally in tropical weather conditions and provide the best cooling shade.
The air temperature could be as much as 25 degrees Fahrenheit (F) cooler under trees than around nearby asphalt lots. As is true for vines, in cool and temperate climates placing trees for summer shade and winter sunshine is more complicated than it would first appear. Trees can reduce summer temperatures significantly, especially when they’re located on the south and west sides of the house. Large specimens that shade the roof and walls from the afternoon sun can reduce indoor temperatures by as much as 8 to 10 degrees F. Trees should be located close enough to the house to cast shade but far enough away (typically about 15 feet) that their roots will not damage the foundation. Homeowners should also consider how wide the trees will become when mature, and space them accordingly.

On small city or suburban lots, the optimum location for a shade tree may be in the neighbor’s yard. Homeowners should work with neighbors to plan and plant an energy-conserving neighborhood landscape that improves conditions and lowers costs for everyone. If that’s not possible, homeowners can use shrubs and vines to shade the walls, windows, and air conditioners.

   
Deciduous trees provide shade in summer, then drop their leaves in autumn, allowing the warmth of the sun to filter through their bare branches and help heat the home when the weather is cold. Maples and other tall species with broad leaves and a high, spreading crown are ideal for this purpose. As few as two or three properly spaced trees with wide crowns may suffice, depending on the size of the house. Prune lower branches for maximum heating of walls and roof by the low winter sun.
A 6- to 8-foot deciduous tree planted near a home will typically begin shading windows the first year. Depending on the species and the height of the home, it will shade the roof in five to ten years.
Smaller trees and shrubs can play a role in an energy-conserving landscape as well. Species with branches lower to the ground can be planted closer to the house than tall shade trees and used for shading east- and west-facing walls and windows from the lower morning and afternoon sun. For the greatest ecological benefit, select species native to the region that offer food and shelter for pollinators and other wildlife. Shrubs planted close to the house can fill in rapidly and shade walls and windows relatively quickly. In wet and humid areas, avoid planting them right up against the house so air can circulate freely.

A good windbreak provides protection in more than one direction. A study in South Dakota found that windbreaks located to the west, north, and east of homes cut their fuel consumption by an average of 40 percent. Houses with windbreaks planted only on the windward side, the side of the prevailing winds, averaged 25 percent less fuel consumption than similar but unprotected homes.

The best windbreaks block the wind close to the ground as well as up high, so homeowners should be sure to include species that have low crowns, such as spruces and firs. Evergreen and deciduous trees and shrubs can also be combined with a wall, fence, or earth berm to lift the winds up and over the house. Some air should be able to pass through the windbreak. Impenetrable barriers create a strong vacuum on the protected or leeward side, causing some of the wind to whip up over the top and down, hitting the house instead of lofting over it. Windbreaks composed of living plants naturally allow some of the wind to penetrate, which makes them more effective.