Cool Paint That Harvests Water From Thin Air
Researchers from the University of Sydney and start-up company Dewpoint Innovations have developed a nano-engineered, paint-like coating that can passively cool buildings and capture water directly from the air – without any energy input. The invention could help address global water scarcity and provide cooling for buildings while reducing the need for energy-intensive systems.
Researchers from the University of Sydney and start-up Dewpoint Innovations have developed a nano-engineered product—a paint-like coating—that can passively cool buildings and capture water directly from air, and without energy input. This discovery could help combat global water scarcity and enable building cooling by reducing the need for energy-intensive systems.
A research team led by Prof. Chiara Neto created a porous polymer coating that reflects up to 97% of sunlight and radiates heat into the air, allowing surfaces to remain six degrees cooler than the ambient air even in direct sunlight. This process creates ideal conditions for water vapour in the atmosphere to condense into droplets on the cooler surface, much like condensation forming on a bathroom mirror.
Prof. Neto from the Sydney Nanoscience Institute and Faculty of Chemistry at the University of Sydney said the findings could have broad implications. "This technology not only advances the science of cool roof coatings, but also opens the door to sustainable, low-cost and decentralised fresh water sources—a critical need in the face of climate change and growing water scarcity," she said.
In a six-month outdoor trial conducted on the roof of the Sydney Nanoscience Hub, water was collected 32% of the year, providing sustainable and predictable water supply even during periods without rainfall. Under optimal conditions, the coatings can collect up to 390 mL per square metre per day—enough for a 12-square-metre surface to meet one person's daily drinking water needs.
The study, published in Advanced Functional Materials, demonstrates that passive cooling and atmospheric water harvesting can be integrated into a paint-like material for large-scale use.
Larger collection areas mean the paint could have diverse industrial applications: water for livestock, horticulture for valuable plants, spray cooling, or hydrogen production. (Electrolysis requires approximately nine litres of water per kilogram.)
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