Second study says Phoenix’s ‘cool pavement’ has positive effect so far

PHOENIX (AZFamily) — The city of Phoenix's innovative plan to lower the surface temperature of asphalt streets during summer months got a boost Thursday night, when researchers from Arizona State University revealed that use of cool pavement reduced the surface temperature of some streets by as much as 12 degrees.

The researchers say the air temperature drop was much less pronounced but still important.

"It is very hard to decrease the air temperature in an open system like this, because air moves around and it mixes," said Jennifer Vanos, who is an associate professor at ASU's School of Sustainability .

"If it does drop at all, that can be important for energy and water. However, we'd like to see as large a decrease as we can with these new products that are created for heat mitigation," added Vanos.

Vanos and her team also revealed that the reflective surface absorbs UV radiation but also reflects some of the sun's heat onto pedestrians .

"If someone is walking in the middle of the road, then they will feel hotter on the reflective surface," said Vanos.

"And that's why we say it's important to think about where this is placed. And we don't want it placed in, in playgrounds, for example, where we're asking children to be active on a more reflective surface," she said.

Ryan Stevens, who is a Phoenix city engineering manager , said the city has applied cool pavement to 107 miles of asphalt in 27 neighborhoods since 2020.

The city plans to apply eight more miles of this surface this season.

But ASU researchers say they still have questions about how long the light gray reflective surface will last .

Vanos said the streets of Phoenix were the best places to get an answer.