Plant Trees, Stay Cool

Green Space Keeps Daily Temperatures Down

Stay cool - plant a tree, says a new NASA study
What can make your city cooler? Adding more trees. In a study published in August, NASA scientists found that trees and vegetation in urban areas reduce daily temperature highs within cities. Urban areas that have a greater percentage of impervious surfaces (concrete, brick, asphalt, etc.) get several degrees hotter than urban areas with tree-lined neighborhoods and other landscaping.

Temperature Difference Between Urban and Vegetated Land Due to Impervious Surface Area - Graphic by NASA

Image by NASA’s Earth Observatory

Reduced air conditioning costs are seen in urban areas with plenty of green space interspersed throughout the concrete. Even the slight increase in temperatures within tree-less cities means up to 20% more a/c use for residents and businesses. More a/c use means higher energy bills and, on the larger scale, strain on the grid.

This effect is not just because of the shade provided by trees, or because plants don’t reflect the sun’s glare the way streets and pavement do; trees actually release water vapor into the air as part of their daily processes. The water vapor cools the air by absorbing heat.

This quick-read from FastCo summarizes the findings.

For a more in-depth explanation, here’s a breakdown of the study’s findings.

For the original scientific details, read the study here.