Jul 21, 2022 - Energy & Environment

"Smart" surfaces could chill overheating cities

Illustration of a city wearing a pair of Illustration of a city wearing a pair of sunglasses.

Illustration: Aïda Amer/Axios

Cities could dramatically reduce peak summer temperatures by replacing hot, dark surfaces — like streets, rooftops, playgrounds and parking lots — with cooler alternatives, according to the Smart Surfaces Coalition, a new advocacy group.

Why it matters: Even as Europe swelters and the U.S. braces for dangerous heat, cities have been slow to embrace mitigation measures — which can be as simple as painting asphalt with inexpensive chemical coatings that block the absorption of solar radiation.

  • Cities have been working "piecemeal" on initiatives like "cool roof" policies and "cool pavement" programs — but they'll only get meaningful results from an inclusive plan that involves all heat-trapping surfaces, says Greg Kats, founder and CEO of the Smart Surfaces Coalition.
  • A full suite of interventions could reduce peak temperatures up to 5 degrees — but make it feel up to 15 degrees cooler, he said.
  • The 3-year-old coalition is working with Baltimore to try to make the city a model of what can be done.

"Cities never think about their entire surface, but they need to," Kats tells Axios. "The objective is to make smart surfaces the urban global design norm within a decade. "

Driving the news: A Smart Surfaces Coalition report on Baltimore found that citywide adoption of smart surfaces over 20 years would create 3,600 jobs, boost tourism and reduce peak summer temperatures by 4.3 degrees in the hottest areas (and 2.5°F on average citywide).

  • A comprehensive strategy — now in its early stages — will (ideally) blitz the Charm City with reflective roofs and highways, solar panels, trees, porous pavements, bioswales to channel rainwater and even "urban meadows," or areas of median where mown grass is replaced with unmanicured native grasses.
  • Baltimore City Councilor Mark Conway — who is also an executive vice president of the Chesapeake Conservancy — has put forward a suite of environmental bills, including a cool roofs ordinance, aimed at ushering in these changes over time.
  • "We're at 27% tree canopy and have a goal of 40%," Conway tells Axios. "One of the big challenges is that there are only so many places to plant trees — and when you’ve got a ton of concrete, it’s very expensive to plant them."

State of play: The Smart Surfaces Coalition is working to coax cities to devise systemic plans to banish dark, impervious surfaces and replace them with green, porous and reflective ones.

  • Its regulatory mapping initiative is building a database of obstacles, like zoning laws, building codes and regulations that discourage or inhibit use of solar panels, green roofs, tree cover and so on in 18,000 cities and towns.
    • For example: "lowest first cost" procurement rules often require that municipalities buy the least expensive surfacing materials — even if they're harmful from a heat perspective.
  • The group helped form the Cool Roadways Partnership of about 30 U.S. cities — a dozen of which (like L.A. and Phoenix) are resurfacing roads in pilot projects of up to 200 blocks.
    • "They're actually measuring a couple degrees ... ambient temperature reduction in adjacent residential areas — so it's starting to happen," said Kats, a noted environmentalist and clean energy investor.
  • It also offers a free online tool for cities to conduct a cost/benefit analysis of converting "hot" surfaces to "cool" ones.

When it comes to smart surfaces, "a lot of interesting stuff is happening on government property" like libraries, schools and city halls, said Amy Turner, a senior fellow at Columbia Law School's Sabin Center for Climate Change Law who leads the Smart Surfaces Coalition's regulatory mapping initiative.

  • "There’s a lot of potential for the local government to use its own buildings or land to promote these policies," she said. "It can help really prove the market for these technologies."

Of note: Smart surfaces are an environmental justice issue. The "urban heat island" effect disproportionately harms low-income neighborhoods, where there's less tree cover — and where cool surfaces are particularly important (yet scarce).

  • A sample project: In Los Angeles' Pacoima neighborhood, GAF, the waterproofing and roofing manufacturer, is coating 10 square blocks with a water-based epoxy pavement coating called StreetBond.
  • GAF anticipates that the project "will offset the greenhouse gas emissions from all of the cars in the neighborhood (roughly 700 vehicles) for nearly three years."

What they're saying: Even though Europe is way ahead of the U.S. in efforts like solar panels, public transportation and reflective surfaces, it still doesn't have a single city that "treats all of its surfaces as one single integrated strategy, as one system for cooling and managing water," Kats said. "Until you do that, it's a bit hodgepodge."

The bottom line: It'll take a lot of political will and concerted effort to legislate and execute bolder and more coordinated smart surfaces plans, but momentum is building.

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