“A tree is a God-created solar powered air conditioner.” — Walter Barrows
As temperatures have soared to record breaking heights I have offered prayers of gratitude for the trees surrounding our home. There are five giant oaks, believed to be nearly two centuries old, whose canopies shade most of the yard. A much younger tree, a sugar maple planted in the early 1980s, grows near the house’s southwest corner and is an invaluable shield against the blistering afternoon sun.
According to the USDA, “The net cooling effect of a young, healthy tree is equivalent to ten room-size air conditioners operating 20 hours a day.” Further, their forest service reports, “Trees properly placed around buildings can reduce air conditioning needs by 30 percent.”
Dr. E. Greg McPherson at the Center for Urban Forest Research has written, “If you plant a tree today on the west side of your home, in five years your energy bill should be 3 percent less. In 15 years the savings will be nearly 12 percent.”
The cooling effect of trees is a two part phenomenon: shade and evaporation. Chicago meteorologist Tim Skilling explained, “Moisture released by tree leaves evaporates into the surrounding air and creates a cooling effect similar to that produced by the evaporation of perspiration from our bodies.” That process (called evapotranspiration), combined with tree canopies blocking sunlight, are why we often feel a cool breeze when walking through shady parks and forests.
It is so easy to take advantage of this natural cooling — simply plant deciduous trees on your home’s southwest corner and western sides. I would suggest maples because they have a beautiful shape and a mature size compatible with most houses. Maple trees are the first to provide pollen for honeybees in the spring and offer glorious autumn foliage. After their leaves fall, sunlight can reach the house to help warm it in winter.