Shade from trees reduces air conditioning needs and makes non-air conditioned homes more comfortable. Plant deciduous trees so they will shade east-facing walls and windows from 7 to 11 a.m. and west-facing surfaces from 3 to 7 p.m. during June, July, and August. Trees with mature heights of at least 25 feet should be planted 10 to 20 feet east and west of the house. Plant smaller deciduous or evergreen trees with lower limbs northwest and northeast of the building to provide late afternoon and early morning shade.
Trees planted to the southeast, south, or southwest will only shade a building in the summer if they extend out over the roof. In the winter, when maximum sun is desired, such trees will provide too much shade. Even deciduous trees that have dropped their leaves cast quite a bit of shade in the winter.
To avoid winter shading, locate trees no closer than 2-1/2 times their mature height to the south of a building. Trees planted to the southeast or southwest should be about four times their mature height from the building.
Trees should also be planted to shade paved areas. Light energy striking dark pavement like asphalt is absorbed, causing the air above to be heated. Light colored pavement absorbs less energy, but can reflect it toward a building. Tree leaves reduce heat and reflection as they absorb light energy and use it to evaporate water.
Air conditioners should also be shaded from mid-morning through evening. Prune branches to allow at least several feet clearance around the air conditioning equipment to encourage air flow. Shrubs should not be planted near the air conditioner or they will reduce air flow and cooling efficiency.