Trees cool by diverting solar radiation from generating heat on the surfaces of buildings into evaporating water and into the conversion of carbon dioxide into wood fiber and oxygen. This evaporative process uses as much as 100 gallons of water per day per tree which is equivalent to the cooling power of five 10,000 BTU air conditioners running 20 hours or more a day. By shielding 20% or more of your home with trees or shrubs, you can reduce your electric cooling bill.

Your heating bill can also be reduced by proper placement of trees. Plant deciduous (leaf shedding) trees on the eastern, western, and southern sides of your home. When leaves are off in the winter, the sun will help warm your home.

Evergreen trees should be planted on the northern side to block cold north winds that can dissipate heat from the outer surfaces of your home and increase cold air infiltration. Low growing evergreen shrubs on the eastern, southern, and western sides of your home will reduce wind flow and allow sunlight to penetrate.

Care must be taken not to block too much air flow. A certain amount is needed to remove excess moisture from building surfaces. Blocking foundation air vents can also prevent removal of excess water from under the house. The results can be mildew under, on and in the house.

Each year, power companies spend millions of dollars in right-of- way maintenance. Much of this work involves pruning trees that were planted under or too close to power lines by well meaning homeowners. Poorly placed and maintained trees can also knock out power during storms. This cost to the power companies is reflected in your electric bill or as a power outage.

When planting trees or shrubs, always allow space for them to reach their mature sizes. Tops of large trees may eventually occupy a quarter acre. Roots of large trees will also occupy slightly more area than the tops. Roots can go as far as five times the height of a tree. Large support roots on large trees are generally within 15 to 25 feet of the base of the tree. These roots will do damage to foundations, sidewalks, and roads. Roots are limited in depth, primarily, by soil oxygen. Roots are in the top eighteen inches of soil with most feeder roots in the top 8-10 inches.

Revised 2/16/2006.