The Heat Island Group staff has been working with American Forests in the Cool Communities Program to promote proper planting and maintenance of urban trees.

Trees, shrubs, and other plants to shade buildings, intercept solar radiation, and cool the air by "evapotranspiration." Planting programs can help reduce urban temperatures and make cities greener. Within ten to fifteen years--the time it takes a tree to grow to a useful size--trees placed in strategic locations can reduce heating and cooling costs by an average of 10-20%. Over their lifetimes, trees can be much less expensive than air conditioners and the energy needed to run them. Link to: Evapotranspiration

Correct selection and location of trees is important to achieve the best results. Two proven methods maximize benefits:

• Deciduous trees shading the south and west sides of a building block the summer sun. For a home monitored in Sacramento, California, Heat Island Group researchers found that this reduced cooling energy use by as much as 30%. Trees, bushes, or vines should also shade your air conditioner, which works more efficiently when kept cool. Also, evergreen trees and bushes to the northwest can protect buildings from cold winter winds.
  
  

• Trees grouped together create a refreshing park or oasis in a city and also cool nearby neighborhoods. Grouped trees can protect each other from the sun and wind, making them more likely to grow to maturity and live longer.