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ASU shade research could help guide urban heat island mitigation strategies

Posted at 6:47 AM, Aug 20, 2021
and last updated 2021-08-20 09:47:15-04

TEMPE, AZ — If you've ever stared down another driver for beating you to that one parking spot underneath a tree, then you understand how much of a difference shade can make when dealing with our brutal summer heat.

But not all shade provides equal benefit, and there is research happening in the Valley that's putting shade to the test.

If you’ve lived in the Phoenix area long enough, you know that we’ve had to learn to live with our intense summer heat by adjusting our lifestyles, limiting our time outdoors, and seeking shade when we do have to be outside.

Shade can reduce the heat load on your body by as much as 50 degrees Fahrenheit on hot and sunny days in the middle of summer, according to Arizona State University assistant professor Ariane Middel.

Middel researches how people experience the heat, and urban heat island mitigation.

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“Shade is really the number one design feature that you can use to keep people comfortable outdoors in the summer,” says Middel.

Middel’s latest research is called “50 Grades of Shade,” and unlike the popular book “50 Shades of Grey” that was meant to heat things up, Middel’s research is meant to help cool things down.

The study was designed to measure the effectiveness of different shade types.

“We categorize shade into three types: one would be natural shade, so that would be shade from trees, or the second shade would be shade from lightweight or engineered structures, that could be umbrella shade, sails, awnings, pergolas, and then the third type of shade is shade from buildings, from walls,” says Middel.

Using MarTy, a cart developed by Middel that measures how the human body experiences heat, researchers tested 159 locations at various times of the day. They found the most effective shade comes from buildings. “If you have a building that's shading the sidewalk, that's essentially the best shade that you can get,” says Middel.

When it comes to trees, Pine trees, Mulberry and Ficus were the most efficient, while Palo Verdes and Mesquites were less effective. However, Middel says that it also depends on tree density and Palo Verdes and Mesquites require less water to maintain while still providing beneficial shade.

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Middel hopes her research helps guide city planning.

“Trees are crucially important for urban environments. But if there are restrictions that prevent you from planting those trees, there are alternatives that you could use to make it more comfortable for people outdoors.”

Middel says, in the end, any type of shade is important.

“Place the shade where people actually are. So it's really important to place shade at bus stops for example, or areas where people exercise where people are active outdoors, or in areas where people cannot afford to plant trees because they don't have the financial means. So shade in those areas is really crucial.”

If you're looking to add a little more shade to your property, SRP offers rebates on professionally installed shade screens and they have a free shade tree program available to their customers. To learn more, click here.