Scientists develop 'smart paint' that reflects 97% of sunlight and could reduce AC use during heatwaves

As heatwaves become more frequent and intense around the world, scientists are exploring new ways to keep buildings cool without increasing energy consumption. Researchers at the University of Sydney, working with startup Dewpoint Innovations, have developed a nano-engineered coating that reflects up to 97% of sunlight and stays significantly cooler than conventional surfaces. The experimental "smart paint" is designed to reduce heat absorption, lower indoor temperatures and potentially decrease reliance on air conditioning. It also has another unusual feature: the ability to capture moisture from the atmosphere and turn it into water droplets without using electricity.The coating uses a specially engineered polymer known as polyvinylidene fluoride-co-hexafluoropropene (PVDF-HFP), which contains microscopic pores that scatter sunlight and minimise heat absorption.Unlike traditional surfaces that absorb solar energy and become hot during the day, the coating reflects most incoming sunlight and radiates heat away from the building. This process, known as passive daytime radiative cooling, allows surfaces to remain cooler even under direct sunlight.Many commercially available cool-roof paints rely on reflective pigments to reduce heat absorption. The new coating uses a porous nano-structure that researchers say can achieve even higher solar reflectance.Laboratory and field tests showed that the coating can reflect up to 97% of sunlight. In some situations, coated surfaces were found to be more than 25°C cooler than dark-coloured roofs exposed to the same conditions.Researchers also reported that surfaces coated with the material could remain up to 6°C cooler than the surrounding air.The technology is designed to lower the amount of heat entering buildings through roofs and walls. Cooler building surfaces can help reduce indoor temperatures, which may lessen the demand for air conditioners and fans during hot weather.While the paint is not intended to replace air conditioning entirely, researchers believe it could contribute to lower energy consumption and reduced electricity costs, especially in regions that experience prolonged periods of extreme heat.One of the coating's most unusual features is its ability to harvest water from atmospheric moisture.Because the surface remains cooler than the surrounding air, water vapour condenses into droplets that can be collected. The process requires no external power source and functions similarly to dew forming on a cool surface.During a six-month rooftop trial at the Sydney Nanoscience Hub, the coating collected moisture for roughly one-third of the year and produced up to 390 millilitres of water per square metre per day under favourable conditions.Researchers believe the coating could have applications beyond residential housing.Potential uses include commercial buildings, warehouses, agricultural facilities, remote communities and urban areas affected by the heat-island effect. The technology may be particularly useful in regions facing both rising temperatures and increasing water stress.Countries such as India, where extreme heat and water shortages are becoming more common, could potentially benefit from cooling technologies that also help capture atmospheric moisture.Not yet. The coating remains in the testing and development stage, with additional rooftop trials continuing in Australia.Dewpoint Innovations is working with industry partners to develop a commercial version that can be applied using standard rollers and spray equipment. Although the company is preparing for market deployment, no official launch date has been announced.Researchers expect further testing will be needed before the technology becomes widely available.As cities around the world grapple with rising temperatures, innovations that reduce heat without increasing electricity use are attracting growing attention. The new smart paint combines passive cooling and atmospheric water harvesting in a single coating, offering a glimpse of how future buildings may be designed to cope with a warming climate. While more testing is required before commercial rollout, early results suggest the technology could become a valuable tool in efforts to reduce energy consumption and improve resilience during extreme heat.