What if paint could replace your air conditioning?
The idea of using white paint to cool buildings is thousands of years old. Now, one professor and his team at Purdue University have created the whitest paint ever. It’s so white it even made the Guinness Book of World Records.
When it reaches the market, Utahns could become less reliant on air conditioning in the hot summer by at least 40 percent. It could also have a profound impact on combating the effects of increasingly hot temperatures.
“Right now there are already what are called cooling paints out there,” said Emily Barber, a PhD student at Purdue University. “They have approximately 80 % reflectance within the solar spectrum. All that means is that all the incoming solar radiation is about 80 % of that going back out, whereas our paints have as much as 95-98 % reflectance.”
Barber has been working on the team led by Dr. Xiulin Ruan. In the spring of 2021, the Purdue engineers unveiled an ultra white paint that can make surfaces as much as eight degrees Fahrenheit cooler than ambient air temperatures at midday, and up to 19 degrees cooler in the evenings.
The engineers also created an ultra-thin formula that is known for its light weight and has good applications for airplanes and automobiles.
“These aren’t just any normal pigments. You can’t just grab some limestone and say let's make calcite, let's go make some paint from this. They are processed in a specific way that basically turns them into nano particles," explained Barber. "These are incredibly small particles that allow them to have this high reflectiveness.”
According to an article released by Purdue, there are two features that give the paint its extreme whiteness. The paint has a very high concentration of a chemical compound called barium sulfate, which is also used to make photo paper and to make cosmetics white.
The second feature stems from the ability of barium sulfate particles to be different sizes in the paint. The variation in particle sizes allows the paint to scatter more of the light spectrum, according to the researchers.
While the new paint sounds expensive, the engineers say it will be cheaper to manufacture than regular paint, and could save about a dollar per day on air conditioning for a one-story house.
“From the beginning when we were developing this paint, we made a lot of attempts to make the process of the paint development very similar to the commercial process,” Barber said. “A lot of the materials and processes are the same and we are hoping for an easy conversion there."
While Barber couldn’t share many details on the commercialization of the paint, she did note that several companies have already had access to the paint. The companies are looking to potentially develop multiple versions of it, depending on which climate the paint will be used in.
“Our lab is also looking at how we can make the paint self-cleaning,” Barber said. “Because such an important part of the paint is its reflectivity. Any sort of soiling, dust, dirt, debris is going to damage that. We want to be able to make it so that it can just wash it away.”
There’s no exact date for when the paint will come to market; however, when it does, Utahns will not only have an easy way to save on their energy bill but Barber said it will also combat climate change from a local level.
“The ultimate conclusion here is that there’s a lot of different ways to combat our changing climate even at a local scale or a global scale and we are just very excited that this technology can be used and help with that fight.”
