Researchers at Purdue University say their ‘ultra-white’ paint reflects more than 98% of sunlight, and could be used to help keep houses cool instead of air conditioning. Commercial white paint typically gets warmer instead of cooler. Paints on the market that are designed to reject heat reflect only 80%-90% of sunlight and can’t make surfaces cooler than their surroundings. According to (opens in new tab)’s Xiulin Ruan, a Purdue professor of mechanical engineering, ‘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. That’s more powerful than the central air conditioners used by most houses.’ But what makes it so white? The paint has a very high concentration of barium sulphate, the same chemical compound that turns photo paper white. They also used different sized particles in the paint to scatter the light more efficiently.  Not only is it the whitest white paint ever, it’s also the coolest. The paint can keep surfaces 19°F cooler than their ambient surroundings at night. It can also cool surfaces 8°F below their surroundings under strong sunlight during noon hours. See: Decorating with white – 10 pure, fresh and oh-so sophisticated ideas A report by the BBC (opens in new tab) says that ‘cool’ white roofs are already being used in New York in a bid to help fight climate change, and more than 10 million square feet of rooftops have been painted white. California has also updated its building codes to push cool roofs. See: 5 secrets to choosing the best white paint shade – the experts advise The report adds that researchers are now working with a company to produce and sell the paint commercially, and that it would be a similar price to paints that are currently available. So it could be appearing on the walls of houses and decorating white kitchens in the not too distant future. See more about eco home improvements in our dedicated guide.