How Reflective Paint Brings Down Scorching City Temperatures
Communities fight urban heat islands with technologies shielding roofs and pavement
3 min
Cities across the U.S. have found relief from this summer’s record-setting heat with the help of technologies that shield roofs, pavement and other surfaces from the sun’s scorching rays.
Some of these technologies have been around for more than a decade but are experiencing greater demand as global temperatures rise. Washington, D.C., for example, has built more than 3,200 green roofs covering 9 million square feet—up from about 300,000 square feet in 2006, according to federal and city officials.
Other technologies, such as super-reflective coatings for pavement, streets and windows, are just now becoming effective and affordable enough for widespread use.
The Los Angeles neighbourhood of Pacoima, a densely packed location sandwiched between freeways and an industrial area, has created a partnership with GAF, a New Jersey-based roofing manufacturer, to paint a basketball court, local park and neighbourhood streets with a reflective coating.
“There’s a lot of asphalt and lack of investment for tree canopies,” said Melanie Paola Torres, 24 years old, a community organiser with the group Pacoima Beautiful. “Given the fact that we are in an industrial zone, that contributes to the urban heat-island effect.”
The reflective coating has reduced air temperatures in the test area at 6 feet above ground by 3.5 degrees Fahrenheit during extreme heat days, and surface temperatures by 10 degrees, according to Jeff Terry, GAF’s vice president of corporate social responsibility and sustainability.
Sweltering conditions are worse in urban heat islands, which can be 10 degrees hotter than surrounding suburbs and occur as buildings, roads and other infrastructure absorb and re-emit the sun’s energy.
Cooling technologies mitigate this. Green roofs absorb heat before it penetrates the buildings beneath. Super-reflective coatings reflect the sun’s visible light and invisible infrared radiation away from surfaces to keep them cooler. And an ultra-white paint developed at Purdue University promises even more protection, although the product isn’t commercially available yet. Each strategy helps reduce energy use.
“The important thing is to help people cool their homes and workplaces affordably,” said Jane Gilbert, chief heat officer for Miami-Dade County, which experienced a record 46 straight days of a 100-degree-plus heat index this summer. “The more efficient we can make both the buildings and the AC systems themselves, the less we’re contributing both to greenhouse gases and also waste heat that goes to our urban heat islands.”
Miami is one of the most vulnerable cities to the urban heat-island effect, along with San Francisco, New York, Chicago and Seattle, according to an analysis by Climate Central, a New Jersey-based nonprofit that researches the effects of climate change. Its analysis found that 41 million people living in 44 cities face an urban heat-island effect of at least 8 degrees. Nine U.S. cities had at least one million people exposed to urban heat of 8 degrees or higher because of the local built environment.
To fight the heat, some cities are leveraging federal money and other incentives to persuade local builders to turn office buildings greener and cooler.
In Miami-Dade County, officials used federal funds to outfit 1,700 public housing units with new low-energy air-conditioning units. Local officials also offered a successful amendment to the Florida state building code requiring cool reflective roofs on all new commercial buildings beginning in 2024, and enrolled 150 structures in a voluntary energy-audit program to track improvements to cut energy use and keep temperatures down.
New York, Chicago, Philadelphia, Toronto and other cities are pushing green roofs with tax breaks and other incentives in an effort to lower energy bills and reduce ambient temperatures, according to Steven Peck, president of Green Roofs for Healthy Cities, a Toronto-based green-roof and -wall industry association. Peck said green roofs can be 30 to 40 degrees cooler than a similar-size blacktop roof, while also cutting waste heat from air-conditioning units.
In the Los Angeles neighbourhood of Pacoima, Torres says residents tell her the streets and playgrounds feel cooler since the reflective coating was completed in August 2022.
“The number-one thing that always comes up is the heat waves when you’re looking down the street,” Torres said. “They don’t see those anymore.”
The next step is to install reflective roofing material on a handful of homes as part of the neighbourhood cooling effort. “We want to keep stacking the solutions to overall create a cool community with multiple strategies,” Torres said.
Altering the urban landscape to adapt to extreme heat requires money and technical know-how, according to city leaders and academic experts. But they also acknowledge the need to keep people safe as global temperatures rise.
“Any one solution is not going to necessarily be able to address the entire problem, but by systematically applying solutions that work in each individual location, we can make a dent in the urban heat-island effect,” said David Sailor, professor of geographical sciences and urban planning at Arizona State University.
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From making unpopular decisions to learning when to listen, leaders from five businesses reveal what nobody prepared them for — and how running a company has challenged their expectations.
Technology and semiconductor shares fell sharply as investors questioned the debt financing the AI infrastructure boom and confronted higher rates and Chinese competition.
Elon Musk is exploring a potential merger between Tesla and SpaceX, a deal that could reshape the future of AI, robotics, autonomous vehicles and space technology. With a combined valuation potentially reaching $3.5 trillion, the move could bring Musk’s vision of an interconnected technology ecosystem closer to reality, although a deal remains uncertain.
5 min
Elon Musk has engineered ties between Tesla TSLA 3.41%increase; up pointing triangle and SpaceX SPCX 7.79%increase; up pointing triangle that are hard to break, and now he wants to fuse them together permanently.
Musk has run both Tesla and SpaceX concurrently over the past two decades, using a schedule that dictated which days he spent focused on each business.
The companies have often shared resources and personnel, signaling their close ties. Last year, SpaceX looked into creating a spacesuit for Tesla’s humanoid robot Optimus, a person familiar with the matter said. Tesla last week showed off its new Roadster, a vehicle featuring SpaceX rocket thrusters that it hopes to soon bring to market.
And in recent months, Musk has repositioned both companies by expanding beyond their core operations toward a shared mission centered on artificial intelligence.
The world’s richest man on Tuesday signaled his interest in tying up SpaceX and Tesla, marking what would be the biggest corporate merger of all time. Because he serves as chief executive of SpaceX and Tesla, Musk said committees of independent directors at both companies are evaluating a possible deal, adding that a transaction might not come to fruition.
The committees will likely evaluate, with lawyers and bankers, how each company would fare in a potential deal and how a deal might best be structured. They then present their conclusions to their respective boards, who typically vote on whether to proceed.
“It’s an odd Kabuki dance where two groups of people are talking and I can’t be in the conversation,” Musk told SpaceX investors on Tuesday in response to an analyst’s question about a potential deal.
For Musk, the merger supports his vision of a world full of autonomous cars, humanoid robots and weekly rocket launches, as well as the data centers and satellites required to keep the whole thing running.
Some investors and analysts said they expect a transaction would be structured as an all-stock deal, with SpaceX potentially paying a modest premium for Tesla shares.
SpaceX, which has a market value of about $2 trillion, said it is seeing sharp growth in revenue across its businesses, which include operating data centers, launching rockets and operating satellite networks such as the internet service Starlink. Tesla is valued at about $1.5 trillion and is expanding its operations beyond its automotive and energy business. Shares in both companies traded higher following the news Tuesday.
Musk’s substantial ownership stakes in both companies, along with voting control at SpaceX, has enabled him to set the deal in motion. Analysts and investors said the deal will probably face regulatory scrutiny internationally, though some see Musk’s close relationship with the Trump administration as an asset to getting approval.
Blurred lines
The companies haven’t said which directors are on the special committees evaluating a potential deal. Several SpaceX and Tesla board members have either personal or business ties to Musk. And like Musk, venture capitalist Ira Ehrenpreis sits on both boards.
In a filing this week, Tesla outlined millions of dollars in business agreements with SpaceX and its subsidiaries last year, including $143 million in car sales to SpaceX, $3.3 million in advertising that it bought on the social-media platform X and $430 million in revenue from the sale of Megapack batteries for SpaceX’s data centers.
The companies also split the cost of resources including the use of Musk’s SpaceX jet and the bill for his personal security, which he runs through a private company.
Employees at both companies routinely move between companies to work on special projects, and some executives have dual roles, including Charles Kuehmann, vice president of materials engineering at both SpaceX and Tesla, and Ashok Elluswamy, the vice president of AI software at Tesla who runs a joint venture with SpaceX called Digital Optimus.
Over the years, Musk has launched new startups within his empire, including brain-implant company Neuralink, underground-tunnel developer the Boring Company and xAI, the AI startup that merged with SpaceX in February.
It is that AI business that Musk thinks can serve a market worth tens of trillions of dollars, justifying the need for a merger.
The business case goes like this: Tesla is developing robotaxis and robots, which it calls “physical AI.” SpaceX is working on the back end of physical AI: the data-center capacity and internet connection required for those robotaxis and robots to operate continuously.
“I don’t see what the value of Tesla is if it’s not merged with SpaceX,” said investment adviser Ross Gerber, a former Tesla bull turned critic invested in both companies. “If they don’t merge, the brains of everything that runs Tesla is owned by another company.”
On top of it all, both companies face constraints on the supply chains they need to make this world a reality, particularly when it comes to chips. To address this, Musk earlier this year announced a joint venture between Tesla, SpaceX and Intel to design and manufacture chips in Texas. “The most epic chip-building exercise by far,” he has said.
Musk at the wheel
For Musk, a merger would also solve two problems: demands on his attention and his lack of control at Tesla.
Tesla for years was Musk’s only public company, a status that came with greater scrutiny. There, Musk reports to a public board, as well as individual investors who make up around 30% of Tesla’s voting power, according to FactSet.
The question of Musk’s attention became a particular focus for investors and the board in recent years after he acquired Twitter in 2022 and launched xAI in 2023, and again in 2025 as he spent time in Washington, D.C., running the Department of Government Efficiency in the early months of President Trump’s second term.
As Tesla’s car business suffered in 2025, Musk threatened to take his AI ambitions outside the company if he wasn’t granted 25% voting control. Last November, Tesla shareholders approved a new pay package for Musk, which created a path for him to vastly expand his stake.
As of Sept. 30, Musk owned a roughly 20% stake in Tesla, according to the company’s proxy filing.
The SpaceX IPO gave Musk a different path. When SpaceX went public in June, the deal’s structure enabled him to have more than 80% voting power at the company—so much that he can’t be fired and decisions can’t be made without his support.
If SpaceX acquires Tesla, he will likely stay in control.
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