A nanoengineered polymer paint-like coating developed by researchers in Australia performs two functions: passive cooling of buildings and collection of water from the atmosphere. As an additional bonus for sustainability, the porous polymer coating tackles this double duty without the need for eternal energy input.

The polyvinylidene fluoride-co-hexafluoropropene formula developed by University of Sydney and Dewpoint Innovations Pty Ltd scientists does not rely on ultraviolet-reflective pigments such as titanium dioxide, and reflects up to 97% of sunlight. By radiating heat into the air, it keeps surfaces up to 6° cooler than the surrounding air, even under direct sun in a process that also fosters conditions for atmospheric water vapor to condense into droplets on the cooler surface.

The water droplets formed on the surface of the self-cooling, weather-resistant film roll off to a collection point. Large collection areas could provide water for horticulture, misting systems for cooling or hydrogen production.

A six-month outdoor study conducted on a roof at the university confirmed that dew could be collected over 32% of the year and provide a sustainable and predictable supply of water even in periods with no rain. Under optimum conditions, the coating described in Advanced Functional Materials can harvest up to 390 ml of water per square meter daily; a 12-square-meter surface bearing the coating could supply the daily drinking needs of one person.