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As global temperatures rise and water scarcity worsens, a nanoengineered paint developed by researchers in Australia aims to tackle both — with the stroke of a brush.
For University of Sydney scientists Chiara Neto and Ming Chiu, these growing pressures sparked an idea: a rooftop coating that could cool buildings and harvest water from the air.
That work evolved into startup Dewpoint Innovations, founded in 2022 with ambitions beyond cooling paint to a broader rethink of how infrastructure is designed: If rooftops across a city could reflect heat and collect water, they could become part of the climate solution.
In a warming world, cities are becoming heat traps. Concrete and rooftops absorb the sun’s energy, raising temperatures, leading to what’s known as the urban heat island effect — where cities experience higher temperatures.
That is the first challenge Dewpoint Innovations is targeting: “Our paint will significantly reduce the heat load the sun puts on cities,” said Chiu, co-inventor and chief technology officer at Dewpoint Innovations.
To achieve that effect, the specially engineered nanomaterials use a process called passive radiative cooling to reflect most of the sun’s energy and release heat back into the sky — allowing roof surfaces to stay cooler than the surrounding air without using energy.
Typical commercial white paint reflects around 70% to 80% of incoming sunlight, said Distinguished Professor Baohua Jia, a nanotech expert at RMIT University in Melbourne, Australia, who is unaffiliated with Dewpoint Innovations.
Dewpoint’s coating demonstrated solar reflectance of up to 96% in a six-month outdoor trial reported in 2025. That higher reflectivity means less heat was absorbed, keeping roof surfaces up to 6 degrees Celsius (11 degrees Fahrenheit) cooler than the surrounding air and reducing heat transfer into buildings.
In a three-month field trial in Sydney in late 2023, Dewpoint’s roof paint stayed up to 30 degrees Celsius (86 degrees Fahrenheit) cooler than a standard dark roof — translating to an estimated reduction of up to 34% in household cooling energy use.
For Jia, those results point to a broader potential. She believes Dewpoint’s roof coating offers a scalable way to curb the urban heat island effect. “This technology can potentially drastically reduce ambient urban temperatures, ease heat stress and reduce reliance on air conditioning, making it a tangible tool for climate adaptation in dense urban areas,” she said.
“One of the amazing properties of having a surface that is maintaining a cooler temperature, while the rest of the environment is increasing in heat, is that it also encourages any moisture in the air to condense on its surface,” Dewpoint chief executive officer Perzaan Mehta told CNN.
It’s the same basic process that causes water to form on the outside of a cold glass.
While still in the development phase, in early trials, the system demonstrated that it could collect 74 liters (19.5 gallons) of water per day from a 200 square meter (2,153 square foot) roof. Metha said this is roughly the amount used by a five-minute shower in areas that have more water abundance.
It cannot replace a home’s full water supply, but Mehta said it can serve as a supplemental source: “It’ll help reduce the burden, but it’s not the miracle cure.”
Through modeling data collected so far, Dewpoint has found that a minimum relative humidity of around 70% is needed for water collection to work — like that found in coastal, tropical areas such as Singapore or the Amazon Basin in South America.
“In the tropics, you’re going to get much better performance, and that’s where we’ve seen a lot of the international interest from our products,” Mehta said.
Jia said passive water harvesting is one of the most exciting, fast-growing trends in the radiative cooling field. While performance varies with humidity, wind and temperature, she said, ongoing field optimizations are improving water yield consistency, even in semi-arid regions.
Dewpoint sees its water capture system being used in a variety of ways: the water could feed into existing rainwater systems for irrigation or be filtered for drinking and household use.
Beyond human applications, the cooling technology could also help support wildlife, Chiu said, by reducing heat stress underneath animal shelters and providing water during droughts.
Between 2019 and 2020, drought and extreme heat fueled months of bushfires across Australia, devastating ecosystems and affecting around 80% of the population. During the crisis, images of firefighters giving water to dehydrated koalas helped shape Chiu’s thinking around atmospheric water capture.
“Water capture systems could be deployed as constructive features in the middle of nowhere to generate water from the air so wildlife can have access to drinking water when they need it and they couldn’t find it anywhere,” Chiu said.
“There is a future where you’d be able to purchase this paint and apply it on your roof,” Mehta said.
Dewpoint is currently preparing for more extensive trials of its paint on Australian rooftops and potentially overseas, with the goal of commercializing the product for distribution through Haymes Paint, an Australian-owned company.
Andrew Brewer, group merchandise and product manager of Haymes Paint, told CNN it is excited to bring this sustainable technology to market.
Brewer noted the barrier to entry into an already-established industry can be tough: “Project builders default to known products,” he said, adding that adoption will depend on independently validated performance, whether the energy savings justify the upfront cost and compatibility with standard application methods.
“Over the longer term, as sustainability and heat management increase in importance in construction, we foresee increased demand for products that contribute to a cooling effect,” Brewer added.
Mehta said that, “In general, we expect to be at a similar price point to functional paints, which tend to be 50-100% more expensive than regular paint,” noting that pricing will be market specific.
Other highly reflective, ultra-white paints are in development to help cool buildings and cut down on air conditioning usage. Researchers are even tapping into machine learning to create an AI-designed cooling paint — that could enable buildings to stay between five to 20 degrees Celsius (41 to 68 degrees Fahrenheit) cooler than traditional paint during midday exposure.
Radiative cooling products still face challenges like durability over time, reduced performance in cloudy or variable weather, slightly higher upfront costs and a lack of standardized testing and building codes, Jia told CNN. But these are actively being addressed, she added, with improvements in materials, design and manufacturing expected to make the technology more reliable and widely adopted.
As research and industrialization continue, Jia says the field of passive radiative cooling will play “an increasingly vital role in cooling cities, cutting carbon emissions and securing water supplies, all without consuming precious energy or relying on artificial refrigerants.”
Dewpoint’s ultimate vision is to see its paint become integral to urban planning and development: “I think it would be fantastic to see Dewpoint as part of the toolkit that city planners and architects have going forward,” Mehta said, “and have products like ours become part of the regulatory framework of how we think about cities being designed.”
