Researchers at the University of Sydney in collaboration with start-up Dewpoint Innovations, have developed a nanoengineered, paint-like coating that both cools buildings and collects water from thin air without the use of energy. The invention is a porous polymer coating that reflects up to 97% of sunlight, radiating heat away, keeping coated surfaces up to 6°C cooler than the surrounding air, even under direct sun. As the surface cools, atmospheric water vapour condenses into droplets the same way steam builds on a bathroom mirror, allowing the coating to harvest the resulting dew.
In field trials on the roof of the Sydney Nanoscience Hub, the team collected condensation over 32% of the year. Under ideal conditions, the system produced up to 390 mL of water per square metre each day, enough that a 12 m² area could meet one person’s daily drinking water needs.
Unlike conventional cool paints that rely on UV-reflective pigments, this formula uses a porous internalstructure to achieve reflectivity, improve durability and reduce environmental impact. The team is now scaling the technology into a water-based formulation that can be applied using everyday rollers or spray tools.
This innovation not only offers a passive cooling solution to reduce urban overheating but also provides a sustainable, low-cost, decentralised source of fresh water — a potentially transformative design for climate resilience and water security.
