This roof coating can reduce surface temperatures by 6°C
What's the story
Australian scientists have developed an innovative roof coating that can passively cool surfaces by up to six degrees Celsius. The breakthrough comes as a potential solution to combat the growing intensity and frequency of heatwaves, which are fueled by human-caused global warming. The new coating not only cools but also extracts water from the atmosphere, making it a dual-purpose technology for extreme weather events.
Technology
How the roof coating works
The innovative roof coating is a porous film that can be applied to existing roofs. It works by reflecting 96% of incoming solar radiation instead of absorbing it. The coating also has a high thermal emittance, which means it efficiently dissipates heat into outer space on clear days. This unique combination of properties is referred to as passive radiative cooling.
Effect
Coating can be cooler than surrounding air
The roof coating has the potential to significantly lower indoor temperatures during extreme heat events. "The paint, even during the day when the sun is out, can be cooler than the air around it," said Prof Chiara Neto from the University of Sydney and lead author of a study on this innovative technology. The coating's cool surface also promotes condensation from atmospheric vapor, similar to dew forming on a car overnight.
Experiment
Researchers tested prototype on Sydney Nanoscience Hub
In a six-month study published in the journal Advanced Functional Materials, researchers tested a prototype of the roof coating on the Sydney Nanoscience Hub. The team paired the cool paint with a UV-resistant topcoat that encouraged dew droplets to roll down into a receptacle. They found that as much as 390ml per square meter per day could be collected for about one-third of the year.
Benefits
Average Australian roof could provide up to 70 liters
Based on the water capture rate from their experiment, researchers estimate that an average Australian roof could provide up to 70 liters on favorable dew-collecting days. The coating could also help reduce the urban heat island effect, where hard surfaces absorb more heat than natural ones, making urban centers 1°C to 13°C warmer than rural areas.
Market
Cool coatings expected to reach commercial release by 2030
The prototype coating was made of poly(vinylidene fluoride-co-hexafluoropropene), a material with environmental issues. However, the researchers are now commercializing a water-based paint with similar properties that is suitable for widespread use. This new paint will be priced similarly to standard premium paints. Sebastian Pfautsch from Western Sydney University, who wasn't involved in the research, expects cool coatings to reach broad commercial release before 2030.