A joint effort by University of Sydney researchers and startup Dewpoint Innovations resulted in a nano-engineered polymer coating that reflects up to 97% of sunlight and maintains surfaces up to 6°C cooler than ambient under direct sun. The cooler surface creates favorable conditions for atmospheric water vapor to condense, enabling this coating to harvest up to ~390 mL of water per square meter per day in optimal conditions, tells Tech Xplore.
During a six-month outdoor study on the roof of the Sydney Nanoscience Hub, the team collected dew over 32% of the year, demonstrating the potential for a predictable water supply even in the absence of rainfall. The coating is based on a porous polymer (polyvinylidene fluoride-co-hexafluoropropene, or PVDF-HFP) rather than ultraviolet-reflective pigments such as titanium dioxide, giving it both high reflectivity and durability under harsh sun exposure.
Beyond providing water, the coating has implications for building efficiency, urban heat-island mitigation, remote water capture, and infrastructure in water-stress or arid regions. The research team emphasizes that dew formation is possible even in semi-arid conditions where night-time humidity rises, challenging assumptions that such technologies only work in humid climates.
The key innovation lies in integrating passive radiative cooling with atmospheric water harvesting in a scalable coating that can be applied like paint using standard rollers or sprayers. Scaling this technology could turn rooftops, external walls, and remote installations into dual-purpose systems: lowering cooling loads while producing potable or process water.
The study points to a novel material solution that addresses both energy- and water-efficiency challenges through one multifunctional surface treatment.