Scientists have developed a paint that reflects more than 98 percent of sunlight, which they say makes it more effective than some air conditioning units. Your energy saving credentials could help tackle the climate crisis.
American engineers have created a paint so white that, they say, coating buildings with it could one day reduce the need for air conditioning. Reducing energy use in buildings is vital to tackling the climate crisis.
Purdue University in Indiana built on efforts to develop a ‘radiative cooling paint’ dating back 50 years.
After six years of research and after studying more than 100 materials, they have developed a paint so effective at reflecting sunlight that it cools surfaces below the surrounding ambient temperature.
How cool is that? Well, they put a number on it. Purdue Studios showed that at the height of the noon sun, the surfaces coated with the paint were 4.5 degrees Celsius cooler than their surroundings. At night, that became 10 degrees Celsius colder.
“If you used this paint to cover a ceiling area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners most homes use, ”said Xiulin Ruan (lead image), a Purdue professor of mechanical engineering.
His team found that commercial ‘heat-rejecting’ paints only reflect about 80-90 percent of sunlight, and actually become warmer than cool.
White paint has long been used on buildings in Greece to reflect sunlight. Image: Clark Van Der Beken
His paint, which reflects the percentage, uses high concentrations of barium sulfate particles, the same chemical compound used in photographic paper, to achieve its dazzling shine. A wide variety of particle sizes means that more of the sunlight spectrum is scattered, including infrared heat.
Purdue scientists believe it is possible to achieve an even whiter shade by increasing the concentration of particles, although they will have to overcome the increased brittleness that this entails.
Main image: Professor Xiulin Ruan with a sample of the whitest paint on record. Credit: Prudue University / Jared Pike