The Surprising Potential of a New White Paint

NYC rooftops that have been painted white in order to reduce the amount of heat absorbed into the buildings (NASA)

Author: Devon Seifer

School: Brooklyn Technical High School

Publication Date: August 22, 2023

This summer, a startling 130° temperature recorded in California broke the record for being what is perhaps the hottest day ever recorded. This comes as the planet is just reaching a similarly unsettling record high global average temperature of 62.9° F. There is no denying that Earth is getting hotter and hotter, and yet many still aren’t prepared for the coming heatwaves. Whether air conditioning is too expensive or someone simply doesn’t have an air conditioner at all, not being able to efficiently and affordably cool down in the summer is a real problem. As of now, there aren’t many effective alternatives to air conditioning, but that may soon well change. In 2020, researchers at Purdue university came up with a new technology that could revolutionize the future of staying cool: white paint.

Specifically, they used barium sulfate (BaSO4) to develop the whitest paint ever to exist. Now this may not sound very revolutionary at first, but its cooling capacity is truly groundbreaking. You may have heard that dark colors absorb heat and that light colors reflect it, and this paint takes the latter to the extreme. Scientifically, BaSO4’s wider range of particle sizes allows it to more broadly scatter a greater portion of the sun’s light spectrum, making it extremely effective at rejecting heat. According to the Purdue research team, “the new whitest paint formulation reflects up to 98.1% of sunlight … and sends infrared heat away from a surface at the same time.” This is a major improvement from the previous norm for reflective paints, which are generally designed to reflect “only 80%-90% of sunlight and [are unable to] make surfaces cooler than their surroundings.”

(WSJ)

Barium sulfate therefore presents itself as a practical measure to keep structures cool. According to more research done by the Purdue team, “if you were to use this paint to cover a roof area of about 1,000 square feet, … you could get a cooling power of 10 kilowatts… [which] is more powerful than the central air conditioners used by most houses.” BaSO4 can also be used on public infrastructure in order to try to cool down large urban regions. The city of Los Angeles has previously tried comparable programs where streets are painted white in an attempt to curb sweltering heat, and although those initiatives were before the invention of barium sulfate paint, they show the paint’s potential and the government’s willingness to engage with it.

This paint is especially appealing for potentially wide commercial use by households and cities alike for its attainability and feasibility. The compound it relies upon for its properties, barium sulfate, is an abundant compound that can be obtained for an affordable cost and is easy to produce. For reference, a 500 g bottle of BaSO4 costs only $25, whereas a similar reflective paint made of Spectralon®, which reflects 99% of light, costs $385. The paint further provides little to no safety concern for the environment or any organism exposed to it (In fact, although it's ill advised, it’s even safe for humans to digest). These factors enable it to be used liberally on homes and in public spaces, ensuring that the paint can be reapplied continuously to ensure its durability.

On a larger scale, the greenhouse gasses emitted by heating and cooling account for 7% of the 51 billion tons of total greenhouse gas emissions every year; that’s 3.57 billion tons of greenhouse gasses. BaSO4 could certainly make a dent in that. Not only would its widespread use mean cutting down on the amount of greenhouse gasses emitted by air conditioning, but it would also mean actively helping cool the Earth. Since the paint reflects light, it would reflect more of the sun’s rays, which would ordinarily absorb into the surface and further heat the planet, back into space. This is a strategy known as negative emissions, by which global warming is fought not by lessening man-made emissions of carbon, but rather by actively removing carbon from our atmosphere. Nevertheless, it should be noted that in order for the paint to actually have any real environmental impact, it would have to be established on a larger and likely global scale, covering somewhere in the range of 1-2% of the earth’s surface.

Xiulin Ruan, professor of mechanical engineering, presents a sample of the seemingly inconspicuous Barium Sulfate paint, the whitest paint on record (Purdue University/Jared Pike)

Unfortunately, unless there is some pivotal change in the political landscape or a drastic increase in the public’s concern towards climate change, the making of barium sulfate paint into a commonplace measure likely won’t come within a few years. More likely, it will be a slow conversion to reflective paint from air conditioning, as many will probably be initially hesitant to break from the tradition of air conditioning, and air conditioning companies themselves will certainly push back with vigor against this shift away from their product. However, the practicality of this paint and its few downsides give it a good chance of being embraced by the public, and, depending on the success of governmental and private efforts to promote its use, may very well become a leading method of cooling within a few decades.

RESEARCH, NOTES, OR BIBLIOGRAPHY:

Purdue News Service. “The Whitest Paint Is Here – and It's the Coolest. Literally.” Purdue University News, Purdue University, 15 Apr. 2021, https://www.purdue.edu/newsroom/releases/2021/Q2/the-whitest-paint-is-here-and-its-the-coolest.-literally..html

Bushwick, Sophie. “'Whitest White' Paint Beats the Heat.” Scientific American, Scientific American, 21 May 2021, https://www.scientificamerican.com/article/whitest-white-paint-beats-the-heat/

Guinness World Records. “How the world's whitest paint could help stop global warming” November 03, 2021, By Sanj Atwal https://www.guinnessworldrecords.com/news/2021/11/how-the-world%E2%80%99s-whitest-paint-could-stop-global-warming-681444

Knighton, Nick, and Bruce Bugbee. “A Mixture of Barium Sulfate and White Paint Is a Low-Cost Substitute Reflectance Standard for Spectralon®.” DigitalCommons@USU, https://digitalcommons.usu.edu/cpl_techniquesinstruments/11/#:~:text=A%20500%20g%20bottle%20of,and%20easily%20rubs%20off%20surfaces

Hotz, Robert Lee. “To Offset Climate Change, Scientists Tout City Trees and Ultra-White Paint.” The Wall Street Journal, Dow Jones & Company, 4 June 2021, https://www.wsj.com/articles/to-offset-climate-change-scientists-tout-city-trees-and-ultra-white-paint-11622822424

How Much Does an Air Conditioner Cost?, 1 June 2022, http://www.thisoldhouse.com/heating-cooling/reviews/air-conditioner-costs/

Venditti, Bruno. “Hotter than Ever: 2023 Sets New Global Temperature Records.” Visual Capitalist, 14 July 2023, www.visualcapitalist.com/charting-global-temperature-records/#:~:text=As%20local%20heat%20records%20are,C%20(62.9%C2%B0F).

Andrius. “Los Angeles Is Painting the Streets White, and There’s a Good Reason Why.” Demilked, 24 Aug. 2017, www.demilked.com/white-streets-heat-climate-change-los-angeles/.