Sep 16, 2021 |
The world's whitest paint might drastically reduce your air condition bill
(Nanowerk News) Want to save big on your air conditioning bills? Wait a few years to coat your home with the world’s whitest paint, which may dramatically reduce or even eliminate the need for air conditioning.
|
The paint, developed at Purdue University, has earned a Guinness World RecordsTM title. The record appears in the 2022 edition of Guinness World Records.
|
Breaking a record for the whitest paint wasn’t a goal for the researchers – curbing global warming was.
|
“When we started this project about seven years ago, we had saving energy and fighting climate change in mind,” said Xiulin Ruan, a professor of mechanical engineering at Purdue, in a podcast episode of “This Is Purdue.”
|
|
Xiulin Ruan, a Purdue University professor of mechanical engineering, and his students have created the whitest paint on record. (Purdue University photo/John Underwood)
|
Ruan invented the paint with his graduate students. The idea was to create paint that would reflect sunlight away from a building. Making this paint really reflective, however, also made it really white. The formulation that Ruan’s lab created reflects 98.1% of solar radiation at the same time as emitting infrared heat. Because the paint absorbs less heat from the sun than it emits, a surface coated with this paint is cooled below the surrounding temperature without consuming power.
|
Typical commercial white paint gets warmer rather than 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.
|
Using this new paint formulation to cover a roof area of about 1,000 square feet could result in a cooling power of 10 kilowatts, Purdue researchers showed in a published paper (ACS Applied Material Interfaces, "Ultrawhite BaSO4 Paints and Films for Remarkable Daytime Subambient Radiative Cooling"). “That’s more powerful than the air conditioners used by most houses,” Ruan said.
|
This white paint is the result of research building on attempts going back to the 1970s to develop radiative cooling paint as a feasible alternative to traditional air conditioners. Ruan’s lab had considered over 100 different materials, narrowed them down to 10 and tested about 50 different formulations for each material.
|
Two features make this paint ultra-white: a very high concentration of a chemical compound called barium sulfate – also used in photo paper and cosmetics – and different particle sizes of barium sulfate in the paint. 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.
|
There is a little bit of room to make the paint whiter, but not much without compromising the paint.
|
The researchers have partnered with a company to scale up the paint and put it on the market.
|