A roof coating developed at the University of Sydney does something most building materials don't: it makes things cooler while generating drinking water, using no energy at all.
The nanoengineered polymer paint reflects 97% of sunlight and radiates heat directly into space. On hot days, surfaces coated with it stay roughly 6°C cooler than the surrounding air. That temperature drop triggers condensation — water vapor in the air turns to liquid droplets that can be collected and drunk.
Over six months of testing on the Sydney Nanoscience Hub, the coating captured dew on more than one third of days, producing up to 390 milliliters of water per square meter. Scale that to a typical Australian roof of 200 square meters, and you're looking at around 70 liters of drinking water on favorable days — enough for a household's daily needs.
We're a new kind of news feed.
Regular news is designed to drain you. We're a non-profit built to restore you. Every story we publish is scored for impact, progress, and hope.
Start Your News DetoxWhy This Matters Now
The timing is pointed. As global temperatures rise, air-conditioning becomes both more necessary and more destructive — it's energy-intensive, which drives emissions, which drives warming. In the regions that need cooling most, though, air-conditioning often isn't an option. Many hot, water-stressed areas can't afford the electricity or don't have reliable grids to run it.
This coating addresses both problems at once. It costs roughly the same as premium paint. It requires no power. And it works even in arid regions where you might not expect water collection — dew forms at night in semi-arid climates as humidity rises, and the researchers found the coating captures it reliably.
"It's not about replacing rainfall," said Chiara Nieto, the chemistry professor who led the work, "but supplementing it — providing water where and when other sources become limited."
The researchers are now scaling up through a startup called Dewpoint Innovations, developing a water-based version that can be applied with standard rollers or sprayers — the kind of equipment already used for regular roof paint. That means installation won't require specialized training or equipment.
The next phase is real-world testing beyond Sydney's climate, particularly in the hot, dry regions where the technology could make the biggest difference.
