Most of you know the legend of Johnny Appleseed, who planted apple trees for the pioneers in the Midwest a couple of hundred years ago. In fact, he was a real person named John Chapman who spent 50 years traveling around the country. And it also turns out he needs to be credited as one of the pioneers in the energy-efficiency field in the United States.

Two new studies sponsored by the U.S. Environmental Protection Agency and the New Jersey Department of Environmental Protection have confirmed what many energy experts have suspected for a long time: Planting trees can dramatically cut down the heat in the area near them and also help keep the air clean.

Research studies over the years have addressed this issue, but the new studies add data that reinforces this energy-saving strategy, especially in big cities where the problem of “heat islands” is most severe.

You’ve likely noticed the heat island effect in hot weather in your own community. Regardless of what the meteorologist says about the temperature, people living in urban areas find it’s a lot hotter because of the heat trapped by the buildings, the dark pavement, asphalt and other dark areas that absorb rather than reflect the sun’s heat.

This can easily cause temperature increases in these areas of 6 to 8 degrees, and the result could be worse than just making you uncomfortable. The hotter weather and higher temperature can cause health problems like heat exhaustion or even asthma attacks while concentrating air pollution and increasing smog formation. And the hotter temperatures mean you’re going to be using air conditioning a lot more, increasing energy costs.

Chapman’s idea of planting trees brought with it the unanticipated benefit of providing shade from the sun while absorbing carbon dioxide and filtering pollutants from the air. The evapotranspiration process you learned about in high school – how trees give off water droplets that draw heat as they evaporate – helps keep the area around them cooler.

Researchers have found that a properly watered tree with a crown of 30 feet can give off as much as 40 gallons of water a day – equivalent to getting rid of all the heat produced by a small electric space heater in four hours. The leaves and branches also absorb sound, give birds and animals a place to live and help prevent erosion. Trees also help block the wind and can provide shade on the walls and roof of your home.

You can get more information from the Heat Island Group at Lawrence Berkeley National Laboratory (eetd.lbl.gov/heatisland). Find out how trees can do a lot more than just make your home look nicer and add to the value of your property.

Ken Sheinkopf is associate director for the Florida Solar Energy Center in Cocoa, Fla.