Scientists at the University of Sydney have developed a roof coating that both lowers the surface temperature by 6°C and collects water from the air. The technology uses passive radiative cooling: heat from the roof escapes into the sky, while the coating reflects up to 96% of solar radiation.
Cooling causes dew to form on the roof, where it can be collected. A 200 m² roof can yield up to 70 litres of water over eight to ten hours at night. The coating is a water-based paint that can be applied like ordinary building enamel. Its formula replaces harmful fluorinated polymers with an environmentally friendly alternative.
The coating helps tackle the urban heat island effect, in which asphalt and concrete accumulate excess heat. The technology is expected to have a particularly noticeable effect in older buildings with poor insulation. Even a partial reduction in roof temperature can noticeably improve indoor conditions, helping to save on air conditioning without compromising comfort.
