Could a White Paint Produce Cooling Power?

You may have heard of the blackest black paint known as Vantablack which absorbs 99.96% of light and can turn 3D objects into visually flat, black holes - now learn about its counterpart. University of Purdue Professor of Mechanical Engineering, Xiulian Ruan, has created a ultra-white paint becoming the whitest paint to date.

The paint, which reflects up to 98.1% of sunlight, can keep surfaces cool enough to eliminate the need for air conditioning. Ruan states, “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 how does it work?

Most white paint only reflects 85% of sunlight and does not cool the surface. The whitest paint, which uses a high concentration of barium sulfate with different sized particles at the broadest spectral scattering, results in the highest reflectance. The paint was even tested during the colder months and with a temperature of 43 degrees Fahrenheit, the paint lowered the temperature by 18 degrees. It can even handle potential outdoor conditions much like commercial paint.

An infrared camera shows how a sample of the whitest white paint (the dark purple square in the middle, on the right) actually cools the board below ambient temperature, something that not even commercial “heat rejecting” paints do. Credit: Purdue University/Joseph Peoples

While the paint isn’t readily available for you to remove the thermostat and cover your house just yet, a patent application for the formulation was filed through the Purdue Researching Foundation Office of Technology Commercialization in October of last year.