The Urban Heat Island and the Benefits of Shade Trees

Written by: Laurel Kruke, Sustainability Manager

Yale University’s Yale Center for Environmental Communication (part of the Yale School of Forestry & Environmental Studies) publishes a daily podcast series called Yale Climate Communications (YCC). YCC is nonpartisan and media-based, where different stories are presented about everyday things that impact the environment. One podcast from March that I enjoyed highlighted energy conservation and how shade trees can help lower energy demand. The full podcast can be accessed here. This podcast got me thinking about shade, and the broader impact of the urban heat island effect on cities like Phoenix.

Living here in Phoenix, we all know how precious shade can be during the summer months, when the sun is beating down. The shade of a tree, for example, can provide an area with a temperature of up to 25°F less than the unshaded areas around it. By shading parts of a building, like a home or a school, users can save on their energy bills by needing to use less energy to cool a space. Shading pavement and ground cover around buildings can also save on energy by reducing the amount of heat being radiated back into the surrounding environment. The less heat that is reflected and radiated back off the ground, the less heat that is absorbed by nearby structures.

Planting trees and other natural vegetation are also great strategies to protect the environment from becoming an urban heat island (when urban areas are hotter than surrounding rural areas). Excess heat is absorbed by the man-made structures and non-natural materials that are prevalent in cities. As the amount of heat that is absorbed increases, temperatures start to increase, and the amount of energy needed to cool spaces also increases. Here are some strategies you can employ at your home, at school, or at another building in which you work/live/play: