Polymer paint-like coating cools buildings, captures water from air

Researchers from the University of Sydney and Dewpoint Innovations have developed a nano-engineered polymer coating that passively cools buildings and captures water from the air without requiring energy input. This porous polymer paint-like material reflects up to 97% of sunlight and radiates heat, keeping surfaces up to six degrees Celsius cooler than the surrounding air under direct sunlight. The cooler surface promotes condensation of atmospheric water vapor, enabling the collection of dew even in dry conditions. In a six-month outdoor trial on the Sydney Nanoscience Hub roof, the coating collected dew on over 32% of days, harvesting up to 390 mL of water per square meter daily under optimal conditions—sufficient for meeting the drinking water needs of one person with a 12-square-meter surface. The coating achieves high solar reflectivity through its internal porous structure, avoiding UV-absorbing pigments that limit traditional cool roof coatings and cause glare. This design balances performance with visual comfort and durability, maintaining robust functionality without degradation under harsh sunlight