The world’s whitest paint can now be used on cars and planes. The paint reflects 98% of the sun’s light, which could help cool vehicle’s interiors saving energy by reducing the need for air conditioning while helping to fight climate change, according to the World Economic Forum (WEF).
The paint was invented by scientists at Purdue University. It’s secret ingredient is a chemical called barium sulphate, which reflects UV light and infrared heat when added to the pigment. Standard white paint only reflects eighty to ninety percent of the sun’s rays, and it absorbs UV light. This prevents heat radiating away, so a surface can never cool below its surrounding temperature.
“If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts,” said Xiulin Ruan, a Purdue professor of mechanical engineering. “That’s more powerful than the central air conditioners used by most houses.”
According to the WEF, Purdue’s product repels infrared heat from a surface and reflects up to 98.1% of sunlight. This outperforms 80%-90% of comparable products and beats the 95.5% of sunlight reflected by the researchers’ previous ultra-white paint.
The Purdue scientists originally formulated the super-white paint for use on buildings, where it can lower surface temperatures by up to 4.5 degrees Celsius providing an energy-efficient way to keep cool. But the paint was too thick for applications where size and weight are important. The new paint, at 0.15 mm, is more than twice as thin as the original. It could even be used on spacecraft.
In an outdoor demonstration, the team showed the paint was able to keep surfaces 19° Fahrenheit (10.5°C) cooler than the ambient surroundings at night. It can also cool surfaces by 8° Fahrenheit (4.4°C) under strong sunlight during noon hours.
Painting walls and roofs white to deflect heat has been done for centuries. Since the 1970s, there have been attempts to develop radiative cooling paint as a workable alternative to traditional air conditioners. This new paint is the result of six years of research.
This month, the team behind the paint announced that they’d made it thinner and lighter, making it suitable for use on vehicles like airplanes and cars.
With global temperatures rising, more and more people are relying on cooling to stay safe and comfortable. The International Energy Agency projects that energy demand from air conditioners will triple by 2050 – equivalent to adding 10 new air conditioners every second for the next 30 years.
The power needed to keep air conditioners and electric fans running accounts for 20% of global electricity use, according to the IEA’s Future of Cooling report.
The WEF reports that in LA some streets and pavements have been painted with a white coating called CoolSeal to help reduce temperatures in the city. This resulted in the streets being 10 to 15 degrees Fahrenheit (5.5C – 8.3C) cooler on average than others, according to the city’s Bureau of Street Services.
Rising temperatures in California’s Death Valley have broken new records recently. In 2020 weather experts recorded the highest ever reported temperature when the mercury climbed to 130 degrees Fahrenheit or 54 Celsius.