A roof paint blocks 97% of sunlight and pulls water from the air.
Researchers at the University of Sydney and commercial start-up Dewpoint Innovations have created a nano-engineered polymer coating that not only reflects up to 97% of the sun’s rays, but also passively collects water. In tests, it was able to keep indoors up to 6 °C (~11 °F) cooler than the air outside.
That temperature differential results in water vapor condensing on the surface – like the fogging on a cold mirror – producing a steady trickle of droplets.
In trials on the roof of the Sydney Nanoscience Hub, the coating captured dew more than 30% of the year, generating as much as 390 mL of water per square meter (roughly 13 fluid ounces per 10.8 square feet) daily. This might not sound like a lot, but a 12-sq-m (about 129-sq-ft) section of treated roof could produce around 4.7 L (around 1.25 US gallons) of water per day under optimal conditions.