Revolutionary Paint That Cools Roofs and Harvests Water
Researchers at the University of Sydney in Australia have engineered a special type of paint that can lower the temperature of a roof by up to 6^{\circ} \text{C} below the ambient air temperature. What’s more, this innovative coating can also harvest potable water from the air, offering a solution for cooling homes and mitigating water scarcity.
With heatwaves becoming increasingly frequent and deadly due to global climate change, this new paint utilizes “Passive Radiative Cooling” (PRC) technology, offering a pathway to keep interiors cool during hot weather.
How the Dual-Action Coating Works
The breakthrough research was led by University of Sydney Professor Chiara Neto.
Exceptional Cooling: The newly discovered paint coating reflects nearly 96% of the sun’s radiation. This prevents the roof from absorbing sunlight and keeps it cool. The paint also has very high thermal emissivity, allowing it to easily radiate heat into the atmosphere, especially on clear skies.
Professor Neto stated: “Even in direct sunlight, the roof painted with this coating stays cooler than the surrounding air.”
Water Harvesting: The cooling effect causes water vapor in the air to condense as dew on the cold surface. While dew usually forms for four to six hours at night, this special coating can sustain condensation for eight to ten hours.
Testing and Commercial Potential
Researchers tested the coating for six months on the roof of the Sydney Nanoscience Hub. They applied an ultraviolet-resistant layer on top of the coating to aid in collecting the dew droplets.
• Yield: The tests showed that the paint can collect up to 390 milliliters of water per square meter per day for approximately one-third of the year.
• Real-World Impact: For a standard 200 square meter roof, this could potentially yield about 70 liters of water per day on a favorable day.
Professor Neto believes this technology can significantly help mitigate the effects of heat in urban areas. “Where insulation is poor, a reduction in the roof temperature will lead to a significant drop in the indoor temperature,” she noted.
The researchers are now working on developing a commercial version of the paint, which they anticipate will be priced similarly to good-quality standard paint.
Professor Sebastian Faucher of Western Sydney University commented that while “Cool Coating” technology has been under development for a decade, it has not yet reached the mass market. He speculates that this may happen before 2030.
