Looking for ways to beat the heat? Plant a tree.

Strategic planting of trees and vegetation around homes and other buildings directly cools the interior, decreasing air-conditioning costs. Greens also can improve air quality, reduce carbon dioxide emissions and storm water runoff, and make your home and community a nicer place to live.

Trees and vegetation cool the air by providing shade, reducing the solar radiation transmitted to underlying surfaces. Cooler walls means less heat transmitted to buildings. Plants also help keep the air cool through "evapotranspiration": They absorb water through their roots and evaporate it through leaf pores.

According to the Environmental Protection Agency, a joint study by the Department of Energy's Lawrence Berkeley National Laboratory and the Sacramento Municipal Utility District in California placed varying numbers of trees in containers around homes to shade windows and walls. The cooling energy savings ranged between 7 percent and 40 percent, and was greatest when trees were placed to the west and southwest of buildings.

That works well in Hawai'i, too, said Matt Flach, head of the Hawai'i Chapter of the American Society of Landscape Architects.

If you want a tree that will grow 20 feet or taller, casting a cooling shadow over your house, Flach said to consider monkeypod, kou or milo; for a medium-sized tree, try kukui. These trees should be planted at least 10 to 12 feet away from the structure, he said, with extra room for monkeypods because of their surface roots.

"You have to make sure your drainage is good," added Flach, a landscape architect with the Department of the Navy.

If you don't have the patience to wait for your tree to grow into a full canopy, large shrubs can give faster cooling results. Flach suggested native hibiscus, copperleaf and sanchezia. "In addition to helping you beat the heat, they add a little color and accent to your garden at the same time," he said.

Shrubs may look small at first, but anticipate that they are going to get big — plant them 4 to 5 feet from your home, Flach said.

Another option is to grow vines on a trellis to shade windows and walls. Flach advises using greenery also to cover outdoor cooling units so they don't have to work as hard, reducing energy costs.

And before pouring heat-collecting concrete, consider ground cover or grass. Flach suggests native ground covers and other xeriscape plants that don't need a lot of water.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.