Scientists develop energy-free cooling paint that produces potable water

A new roof paint could allow you to stay cool while providing water to drink. Australian researchers have developed a nanoengineered polymer coating that reduces surface temperature by up to 6 °C even on hot days, and that harvests moisture from air.

The coating should cost slightly more than premium paints, and would provide heat relief and potable water without using energy. It could be a boon for heat- and water-stressed regions of the world, and prove valuable during extreme heat events and in emergencies. As temperatures around the world rise due to climate change, energy-intensive air-conditioning adds fuel to the fire of global warming. The worst effects are being felt in already hot regions of the world.

In many of these areas, air-conditioning isn’t an options because of affordability and unreliable power grids. These are also often the regions that suffer from water scarcity. Researchers at the University of Sydney hope their new coating material could provide sustainable, low-cost source of cooling and drinking water. Ultrawhite, or colorful paints that reflect most of the sunlight falling on them are a common way to cool down buildings.

Researchers have also developed other novel paints and passive cooling materials for the purpose. But the new coating is a nanoporous film of polyvinylidene fluoride-co-hexafluoropropene. The microscopic pores scatter sunlight in all directions without glare. The material reflects up to 97% of sunlight and radiates heat directly into space through the atmosphere.

.IRPP_ruby , .IRPP_ruby .postImageUrl , .IRPP_ruby .centered-text-area {height: auto;position: relative;}.IRPP_ruby , .IRPP_ruby:hover , .IRPP_ruby:visited , .IRPP_ruby:active {border:0!important;}.IRPP_ruby .clearfix:after {content: "";display: table;clear: both;}.IRPP_ruby {display: block;transition: background-color 250ms;webkit-transition: background-color 250ms;width: 100%;opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: #eaeaea;}.IRPP_ruby:active , .IRPP_ruby:hover {opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: inherit;}.IRPP_ruby .postImageUrl {background-position: center;background-size: cover;float: left;margin: 0;padding: 0;width: 31.59%;position: absolute;top: 0;bottom: 0;}.IRPP_ruby .centered-text-area {float: right;width: 65.65%;padding:0;margin:0;}.IRPP_ruby .centered-text {display: table;height: 130px;left: 0;top: 0;padding:0;margin:0;padding-top: 20px;padding-bottom: 20px;}.IRPP_ruby .IRPP_ruby-content {display: table-cell;margin: 0;padding: 0 74px 0 0px;position: relative;vertical-align: middle;width: 100%;}.IRPP_ruby .ctaText {border-bottom: 0 solid #fff;color: #0099cc;font-size: 14px;font-weight: bold;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .postTitle {color: #000000;font-size: 16px;font-weight: 600;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .ctaButton {background: url(https://www.anthropocenemagazine.org/wp-content/plugins/intelly-related-posts-pro/assets/images/next-arrow.png)no-repeat;background-color: #afb4b6;background-position: center;display: inline-block;height: 100%;width: 54px;margin-left: 10px;position: absolute;bottom:0;right: 0;top: 0;}.IRPP_ruby:after {content: "";display: block;clear: both;}Recommended Reading:This one trick could slash cooling energy use on server farms by up to 56% When exposed to the sky, even under direct sun, the coating keeps the surface underneath 6°C cooler than ambient temperature. Because the surface is cooler, it promotes the condensation of water vapor on it, which can be collected. “While humid conditions are ideal, dew can form even in arid and semi-arid regions where night-time humidity rises,” said Chiara Nieto, a professor of chemistry who led the work, in a press release.

“It’s not about replacing rainfall but supplementing it – providing water where and when other sources become limited.” In a study published in the journal Advanced Functional Materials, the researchers tested the material for six months on the roof of the Sydney Nanoscience Hub. They painted tilted panels with the cooling paint and topped it with a UV-resistant topcoat that promotes dew droplets to roll down into a receptacle. The coating captured dew more than 32% of the year, producing as much as 390 millileters of water per square meter.

This translates to a 12 square meter roof area producing around 4.7 liters of water per day under ideal conditions. And that means, based on the researchers’ calculations, that an average Australian roof, which is about 200 square meters in area, could provide up to 70 liters on favorable days.

The researchers are now scaling up and commercializing the coating through the start-up Dewpoint Innovations. The company is developing a water-based formulation that can be applied with common rollers or sprayers. Source: Chiu, M. Passively cooled paint-like coatings for atmospheric water capture.

Advanced Functional Materials, 2025. Image: ©Anthropocene Magazine