Researchers Find the Whitest Shade of Paint. It Could Slow Global Heating


Apr 16, 2021


Image Credit: Istock

Researchers have developed the lightest shade of white paint, and hail this finding a major victory in the fight against the climate crisis. When applied to buildings, the paint has a cooling effect, reduces the need for air conditioners, lowers the level of carbon emissions, and slows the process of global warming.

“Our paint can help fight against global warming by helping to cool the Earth – that’s the cool point,” Xiulin Ruan, study co-author and a professor of mechanical engineering at the University of Purdue, said in a statement.

Published in the ACS Applied Materials & Interfaces journal, the study shows that this particular shade of white paint reflects up to 98% of sunlight, and also sends away infrared light — energy that we feel as heat — from a surface back to space. As part of the electromagnetic spectrum, infrared light from the sun accounts for 49% of the Earth’s heating.

Basically, instead of absorbing heat, the paint is deflecting it in a way. These properties make the paint a valuable tool to help cool buildings — its use can positively impact areas most affected by rising temperatures, a result of global warming.

“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,” Ruan said. Experts have previously noted that cutting down the use of air conditioners would be a major win for the planet, as carbon emissions from air conditioners are responsible for depleting the ozone layer and contribute to global warming.

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Three factors are responsible for the paint’s cooling performance. First, barium sulphate, a compound of barium mineral, was used as the pigment which, unlike conventional titanium dioxide pigment that is usually used for developing paints, does not absorb the sun’s ultraviolet light and thus promotes a cooling effect. Second, a high concentration of the pigment was used – almost 60% — making it more reflective than average commercial white paint.

“We found that [via] using barium sulfate, you can theoretically make things really, really reflective, which means that they’re really, really white.” Xiangyu Li, study co-author and a postdoctoral researcher at the Massachusetts Institute of Technology said in a statement.

Another factor that made the paint hyper-reflective was the different sizes of barium sulfate particles in the paint. “A high concentration of particles that are also different sizes gives the paint the broadest spectral scattering, which contributes to the highest reflectance,” Joseph Peoples, a Purdue Ph.D. student in mechanical engineering, said in a statement.

As researchers now work to file patents and move towards mass production of the paint, this research shows the potential of unique interventions, such as the production of paint color, in becoming valuable in the fight against climate change. Though using paint for cooling is not a new phenomenon, it remains to be seen if this highly reflective paint can work in large-scale, practical situations yet.


Written By Aditi Murti

Aditi Murti is a culture writer at The Swaddle. Previously, she worked as a freelance journalist focused on gender and cities. Find her on social media @aditimurti.


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