Ylenia Aguilar raised her two sons in Arizona — first in Tucson and later Phoenix, so they’re no strangers to scorching heat. Just recently, Phoenix hit its 100th straight day at or above 100 F (37.8 C), shattering the record set in 1993.
She remembers scary moments “seeing soccer kids and my own children pass out and faint from, you know, heat-related illnesses,” she said. “It was seeing my sons dehydrated.”
Scores of U.S. schoolyards like hers are carpeted in heat-absorbing asphalt, with no shade even for play areas. The buildings were often made with wall and roofing materials that radiated heat into indoor spaces. Kids are also more vulnerable to heat illness than adults. Their bodies have a harder time self-regulating in extreme heat in part because they sweat less, so they can become dehydrated faster. Climate change is heightening the risks. School closures related to heat are becoming more frequent, according to a report by the Center for Climate Integrity and the firm Resilient Analytics.
There is also accumulating data on temperature inequality and the effects of heat. Low-income neighborhoods and communities of color, which describes Aguilar’s, can be as much as 7 F (3.9 C) hotter than richer and whiter neighborhoods, leaving students and educators to swelter in a warming world. Extreme temperatures also affect learning, performance and concentration.
Yet there are well-known ways to cool down schools and neighborhoods. “When the solutions are so at hand and readily available,” said Joe Allen, associate professor and director of the Healthy Buildings program at the Harvard T.H. Chan School of Public Health, these conditions are “unacceptable.”
In Phoenix, Aguilar became a leader, joining the school board and helping to pass a $50 million bond that funded a number of solutions in her Osborn Elementary School District.
Other schools like Aguilar’s are also starting to spend on these fixes.
On a hot day in 2022, students at a school near Atlanta pointed thermometers onto their basketball court and got a reading of 105 F (about 40.5 C).
A roofing manufacturer donated a bright blue, solar-reflective coating and helped them paint it on. They took another reading, this time it was 95 F (35 C).
As students of the private school learned, paved surfaces get really hot in the sun. They absorb solar energy and slowly re-radiate it out as heat, increasing air temperatures by as much as 7 F (3.9 C).
Cooling playgrounds and roads by making them more reflective is not new, but interest has been growing along with more understanding of the way the accumulation can affect entire neighborhoods, known as urban heat islands, said Daniel Metzger, a fellow at Columbia Law School who studies these passive climate adaptation technologies.
“And as climate change gets worse… I think adaptation measures like this are only going to become more and more important,” he said.
Workers recently rolled that same cool surface on the parking lot at the Science, Arts and Entrepreneurship School as part of the school’s sustainability goals and efforts to minimize heat. Both times, the roofing manufacturer GAF donated the coatings and labor. Without that, the school would have had to raise funds, said Scott Starowicz, the school’s co-founder and chief financial officer.
With the new, cool surfaces, Starowicz said he feels “like we’re doing our part” to mitigate heat.
East of Los Angeles, roofs across the Chaffey Joint Union High School District used to reach 140 F (60 C), officials said. Hot roofs can make upper-floor classrooms unbearable.
This affected a lot of kids. Chaffey is the second-largest high school district in California with 24,000 students. Nearly 65% are Latino or Hispanic.
Chaffey has now spent $11.4 million in bond money and maintenance funds to convert asphalt shingle roofs to white cool roofing since 2017 — part of district-wide conservation and sustainability efforts. It’s important as California heats up; this past July was its hottest on record.
These roofs — as well as window films, paints and other technologies — reflect a portion of the incoming solar radiation away from a building, rather than allowing it to transfer into the building as heat. These are some of the easiest and least costly actions a district can take.
Experts agree cool roofing does bring down the indoor temperature and reduce the need for AC. Chaffey’s roofs now sit at around 90 F (32 C).
The district has also invested in steel shade structures, trees and thermometers that consider things like temperature and humidity to monitor heat stress. “There’s a high level of urgency,” said Rick Wiersma, assistant superintendent of business services.