What Is Reflective Cooling Paint and Why It Matters
Reflective cooling paint is a nano-engineered, paint-like coating designed to reflect nearly all incoming sunlight and release heat into the sky, keeping building surfaces significantly cooler than the surrounding air without using any electricity. Developed by researchers at the University of Sydney in collaboration with startup Dewpoint Innovations, this heat reflecting coating bounces back up to 97% of sunlight instead of absorbing it. At the same time, it uses passive radiative cooling to send heat away from roofs and walls. Tests show that coated surfaces can stay up to 6°C cooler than the ambient temperature under direct sun. For households facing hotter summers and rising cooling demand, this type of energy efficient paint points to a future where comfort depends less on air conditioners and more on smart, passive cooling technology built directly into the building envelope.
How the Nano-Engineered Heat Reflecting Coating Works
The new reflective cooling paint relies on passive radiative cooling, a natural process where surfaces emit heat as infrared radiation into the atmosphere. Unlike conventional paints and roofing materials that absorb solar energy and warm up, this coating reflects 97% of sunlight, sharply limiting heat gain. At the same time, it is engineered to radiate thermal energy away so that the painted surface can drop below air temperature. According to the research team, “the surface can stay up to 6°C cooler than the surrounding air under direct sunlight,” a performance that stands out among passive cooling technologies. Because it is applied like conventional paint, it can be added to existing roofs and walls without complex installations, turning everyday surfaces into active cooling elements that work continuously, without power, fans or refrigerants.
Cutting Cooling Bills with Passive Cooling Technology
By preventing buildings from heating up in the first place, reflective cooling paint could reduce how often air conditioning runs during hot periods. Lower roof and wall temperatures mean less heat flows indoors, so air conditioners can be smaller, run for fewer hours, or be turned off altogether during milder days. In many regions, cooling already uses a large share of electricity, and demand is expected to climb as heatwaves become more frequent. A widely deployed heat reflecting coating would ease pressure on power grids during peak afternoon hours and help households and businesses cut cooling expenses. While exact savings will vary with climate, building design and insulation, the principle is straightforward: every degree of passive cooling provided by an energy efficient paint is a degree that mechanical cooling does not need to supply.
Bonus Benefit: Harvesting Water from Warm Air
Beyond cooling, the coating’s ability to run cooler than the surrounding air creates conditions for water to condense on its surface. When the painted surface cools below the dew point, moisture from the air turns into fine droplets that can be collected, similar to early-morning dew on grass. Tests cited by the researchers show that the coating collected up to 390 milliliters of water per square meter per day in favorable conditions, and they estimate a 200-square-meter roof could yield up to 70 liters on good days. The study also reports that the paint can extend the dew collection period by several hours. This will not replace full water supply systems, but it could provide a useful supplementary source of clean water in areas facing intermittent shortages or unreliable infrastructure.
From Lab Roof to Real-World Energy Efficient Paint
To move beyond theory, the team tested the coating outdoors on the roof of the Sydney Nanoscience Hub for six months, exposing it to shifting weather, sunlight and humidity. The extended trial showed that the material maintains its cooling and water-condensing performance in real conditions, not only in controlled experiments. Equally important, the researchers have designed the material as a paint-like product, which makes large-scale use more realistic than more complex cooling devices that can be expensive or difficult to install. If commercialised, this passive cooling technology could be rolled out on homes, warehouses, factories, schools and public buildings to cut heat gain and provide modest water collection. While it will not eliminate the need for air conditioning everywhere, it offers a practical, low-energy tool to improve summer comfort and resilience as temperatures continue to climb.