San Antonio to be the first Texas city to try out cooler pavement to combat warm temperatures

City hopes pavement topper is answer to combating urban heat island effect

The lack of tree canopy or greenery, and heat-retaining materials like concrete walls and asphalt can result in much warmer temperatures in urban areas.

SAN ANTONIO – The lack of tree canopy or greenery, and heat-retaining materials like concrete walls and asphalt can result in much warmer temperatures in urban areas.

It’s called the urban heat island effect. It leads to significantly warmer temperatures in the city during the summer months. It’s a problem the City of San Antonio is aware of and attempting to find ways to combat.

“What’s important about the urban heat island is that heat is absorbed all throughout the day,” said Murray Myers, the municipal sustainability manager for San Antonio’s Office of Sustainability. “It’s supposed to cool down at night, and it doesn’t because all that heat is then released back into the neighborhoods.”

According to a UTSA study on urban heat islands, San Antonio, specifically the city’s east and west sides, can be anywhere from 10-20 degrees warmer in the summer compared to nearby rural areas.

The following images were taken from UTSA’s Heat Vulnerability Assessment Tool. They show the average monthly surface temperature in August 2019:

Downtown San Antonio and King William are seen in UTSA’s Heat Vulnerability Assessment Tool. It shows the average monthly surface temperature in August 2019. (University of Texas at San Antonio)
San Antonio is seen in UTSA’s Heat Vulnerability Assessment Tool. It shows the average monthly surface temperature in August 2019. (University of Texas at San Antonio)
North-Central San Antonio is seen in UTSA’s Heat Vulnerability Assessment Tool. It shows the average monthly surface temperature in August 2019. (University of Texas at San Antonio)
Kelly Field is seen in UTSA’s Heat Vulnerability Assessment Tool. It shows the average monthly surface temperature in August 2019. (University of Texas at San Antonio)

“You’ll see how places like Olmos Park, the older tree canopy and river/trail in King William and the forested area Northwest of Kelly Field are cooler than the paved surfaces in the same area,” Myers said. “Within the city, there are pockets of green space where the surface temperatures are at least 15 degrees cooler, and that correlates with an ambient air temperature decrease in those areas.”

“As we collect more data from the surrounding counties, we’ll be able to provide a more definitive answer on the temperature decrease between San Antonio’s core and the surrounding rural areas.”

It’s why San Antonio is leading the charge in Texas, being the first city in the state to test out cooler pavement.

It’s basically a pavement topper by the company GuardTop that has been shown to fight the urban heat island effect and not retain as much heat as asphalt or concrete.

“In this situation, it’s a seal coat,” Myers said. “It has a couple of different materials to make it more reflective, a little bit lighter that way the sunlight isn’t absorbed into the pavement.”

Myers said the cooler pavement was given to the city as a sample.

The University of Texas at San Antonio and the city will conduct a study on the small applied area near the Hays Street Bridge over the next several months.

If proven successful, the city will invest in the material to start applying it to the most impacted neighborhoods, possibly by next fall.

Studies in other cities have shown it does work, and Los Angeles and Phoenix are already using the cool pavement.

Arizona State University conducted a study in Phoenix in 2020 that showed cool pavement had an average surface temperature 10.5 to 12 degrees lower than traditional asphalt at noon and during the afternoon hours.

Sub-surface temperatures averaged 4.8 degrees lower in areas treated with the cool pavement. Nighttime air temperature at 6 feet high was on average 0.5 degrees lower over cool pavement than on the non-treated surfaces.

”If we locate or strategize our resources into the hotspots, then we can lower those temperatures and then tackle the next neighborhoods,” Myers said.

He said this is just one tool in the toolbox when it comes to combatting warming temperatures in the city, and planting more trees also plays a big role.

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About the Authors:

Sarah Acosta is a weekend Good Morning San Antonio anchor and a general assignments reporter at KSAT12. She joined the news team in April 2018 as a morning reporter for GMSA and is a native South Texan.

Azian Bermea is a photojournalist at KSAT.