A healthy front lawn has the same cooling effect as an 8-1/2 ton air-conditioning compressor according to a Mississippi State University study. The plants transpire, or evaporate water through the leaves surface, to cool themselves. In addition to cooling themselves off, the keep the immediate area cool as well. About half of the heat energy directed to a turf area is eliminated by transpiration.
"When the temperature of the sidewalk is 100 degrees Fahrenheit, the temperature of the adjacent lawn remains near 75. This cooling may last into the night, with studies showing a 13-degree cooling at 9 p.m." scientists say.