WEST LAFAYETTE, Ind. — Researchers at Purdue University say they’ve developed the world’s whitest paint that’s designed to reduce or even eliminate the need for air conditioning.
Xiulin Ruan, a mechanical engineering professor at Purdue, invented the paint with his graduate students. Their mission was to create a product that would reflect sunlight away from a building to save energy and help combat climate change.
The formulation they created reflects 98.1% of solar radiation while also emitting infrared heat. Because the paint absorbs less heat from the sun than it emits, a surface coated with the paint is cooled below the surrounding temperature without consuming power, according to Purdue.
The Indiana college says typical commercial white paint gets warmer rather than cooler in the sun, with paints on the markets designed to reflect only 80-90% of sunlight.
Researchers showed in a published paper that using their formulation to cover a roof area of about 1,000 square feet could result in a cooling power of 10 kilowatts. Ruan says that’s more powerful than air conditioners used by most houses.
Purdue says Ruan’s lab considered more than 100 different materials before narrowing them down to 10 and testing 50 different formulations for each material.
According to the university, the researchers made the paint ultra-white by using a high concentration of a chemical compound called barium sulfate, as well as using different particle sizes of the compound.
“What wavelength of sunlight each particle scatters depends on its size, so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun,” the university explained.
The school says there’s “a little bit of a room” left to make the paint even whiter, but not much without compromising the product.
Earlier this year, the product earned the Guinness World Records title “whitest paint” and it will appear in the “Guinness World Records 2022” book.
Patent applications have been filed and next, the researchers are hoping to scale up the paint to put it on the market through a partnership with a company.