A new ultra-white paint developed by a team of researchers from Purdue University in the US is the coolest. Literally. The whitest and coolest paint ever made reflects 98 per cent of sunlight and radiates infrared heat back into space.
The paint is a few shades whiter than snow and safe for humans to look at. Its unique pigment means it is capable of cooling surfaces to 4.5C below the ambient temperature, something that no other refelctive paint on the market is able to do. Existing white paints can reflect 80-90 per cent of sunlight and absorb UV, but can't lower the ambient temperature of surfaces.
The researchers behind the ultra-white paint believe their product could provide an affordable and environmentally friendly solution for cooling buildings. The concept of using white paint to cool buildings in not new, but with global temperatures rising, products like this one could help buildings reduce their reliance on air conditioning and associated emissions.
"Our paint can help fight against global warming by helping to cool the earth," lead researcher professor Xiulin Ruan told the Guardian. "Producing the whitest white means the paint can reflect the maximum amount of sunlight back to space."
Painting a 1,000 square foot (93 square metre) area of roof would provide a cooling power of 10 kilowatts.
"That's more powerful than the central air conditioners used by most houses," Ruan explained.
So how does it work? The paint uses a highly concentrated barium sulphate pigment (which reflects UV) instead of the titanium dioxide pigment used in regular paint (which absorbs UV). The paint also uses different sized pigment particles to more effectively scatter the spectrum of light coming from the sun.
While additional testing of the product's durability and scalability is needed, researchers say it could be on the market in less than two years.