What Is Reflective Cooling Paint and Why It Matters
Reflective cooling paint is a nano-engineered, paint-like coating designed as a passive cooling technology that reflects most incoming sunlight and radiates heat away from buildings, helping surfaces stay several degrees cooler than the surrounding air without using electricity or mechanical air conditioning systems. Developed by researchers at the University of Sydney with startup Dewpoint Innovations, this heat reflective coating can reflect up to 97% of sunlight and release stored heat into the sky. Because it absorbs so little solar energy, roofs and walls coated with this energy efficient paint warm up far less under direct sun. Researchers report that coated surfaces can remain up to 6°C cooler than the ambient air, lowering indoor temperatures and easing demand for air conditioning. In a warming climate, that kind of passive cooling could become a practical tool for keeping homes comfortable in hot seasons.
How the Nano-Engineered Coating Cools Buildings
The new reflective cooling paint works through a process called passive radiative cooling. Instead of absorbing solar energy like conventional dark roofs and walls, the coating reflects the vast majority of visible and near-infrared sunlight. At the same time, it emits the heat it does absorb as infrared radiation toward the sky, where it can escape into the upper atmosphere. Because of this dual action, a coated surface can drop below the surrounding air temperature under clear skies, even in direct sunlight. According to researchers at the University of Sydney, the coating reflects up to 97% of incoming sunlight and can keep a surface up to 6°C cooler than the ambient air. For homeowners, that temperature difference can translate into noticeably cooler rooms, less reliance on air conditioners and lower energy use during hot afternoons.
Cutting Cooling Bills With Passive Technology
For households and businesses, the appeal of this heat reflective coating lies in energy savings and resilience. Buildings typically absorb large amounts of heat during the day, driving up indoor temperatures and forcing air conditioners to work harder. As global temperatures rise, this demand strains power grids and raises energy costs. By adding a highly reflective, energy efficient paint layer to roofs or exterior walls, property owners could reduce peak indoor temperatures before turning on any mechanical cooling. That means air conditioners, if still used, run for fewer hours and at lower intensities. Over time, lower electricity use could reduce bills and cut emissions linked to cooling. Because the coating behaves like conventional paint, it avoids the heavy installation costs that limit uptake of many advanced cooling systems, making it a practical passive cooling technology for homes, warehouses, schools and public buildings.
A Surprising Bonus: Harvesting Water From Air
Beyond cooling, the reflective cooling paint can also pull small amounts of clean water from the air. When the coated surface cools below the surrounding air temperature, water vapour in the air condenses into droplets on the surface, similar to morning dew forming on grass. Tests show that, under favourable humidity and temperature conditions, the coating can collect up to 390 millilitres of water per square metre per day. Scaled to a 200-square-metre roof, that could mean as much as 70 litres of water on good days. This is not a complete answer to water shortages, because yields depend heavily on climate, weather and surface size. However, it could offer an extra source of potable water for remote buildings or water-stressed communities, working in tandem with its main role as a passive cooling technology.
From Lab Roof Tests to Real-World Homes
To move from theory to practice, the research team tested the energy efficient paint outdoors for six months on the roof of the Sydney Nanoscience Hub. The long trial allowed them to observe performance in real weather, including swings in temperature, sun angle and humidity. Results showed that the coating did not only keep the surface cooler than ambient air but also extended dew collection periods by several hours, increasing the window for water harvesting. Designed to apply like ordinary paint, the material is meant to be compatible with common roof and wall surfaces, which could speed up adoption compared with complex mechanical systems. The partnership between the University of Sydney and Dewpoint Innovations signals an intent to bring the heat reflective coating to market, with potential applications in homes, factories, warehouses, schools and other large buildings that face intense summer heat.
