March 14, 2023

Purdue’s ‘world’s whitest paint’ wins 2023 SXSW Innovation Award

Technology wins sustainability category for world-changing potential

WEST LAFAYETTE, Ind. – The world’s whitest paint, developed by Purdue University researchers and recognized in Guinness World Records, has been named winner of the 2023 Innovation Award in the sustainability category by South by Southwest Conference & Festivals (SXSW).

The award “recognizes the most exciting creative developments in the connected world,” and was presented to Purdue on Monday (March 13) at the 25th annual SXSW Innovation Awards Ceremony in Austin, Texas. Purdue was chosen in the sustainability category from among four finalists that included Purdue; Indianapolis-based Atarraya: Sustainable Shrimp-Farming Tech; The Trees of the Future, based in Hayward, California; and Chicago-based Natures Fynd: Fy Protein.

The paint, developed by Purdue professor of mechanical engineering Xiulin Ruan, is fighting global warming by keeping surfaces cool enough to reduce the need for internal air conditioning. SXSW is the latest to recognize the innovation, which was previously featured on PBS NewsHour and The Late Show With Stephen Colbert. Earlier this month, the paint was named winner of the 2023 Gizmodo Science Fair.

ruan-sxsw Professor Xiulin Ruan presents to SXSW attendees in Austin, Texas during the Innovation Awards Finalist Showcase. (Purdue University/Christy McCarter) Download image

In 2022 Ruan and his team innovated further by developing a new formulation of his groundbreaking paint that is now thinner and lighter – ideal for radiating heat away from cars, trains, airplanes and even spacecraft. According to Ruan and his team’s models, covering 1% of the Earth’s surface in their technology could mitigate the total effects of global warming, a fact encouraging them to continue pursuing formulas suitable for surfaces like asphalt and roadways (podcast available online).

“With this award, we are honored that SXSW joins a growing list of organizations, publications, and states that recognize Purdue University and its world-changing researchers are delivering practical solutions to today’s toughest challenges,” said R. Ethan Braden, executive vice president, chief marketing and communications officer for Purdue University and Purdue Global. “Whether it’s the world’s whitest paint to combat global warming or the workforce needed to onshore semiconductor production in the United States, Boilermakers are delivering innovative giant leaps again and again.” 

Painting the town white to go green

Typical commercial white paint gets warmer rather than cooler when subjected to sunlight or other light sources. Paints on the market that are designed to reject heat reflect only 80% to 90% of sunlight and can’t make surfaces cooler than their surroundings. 

In comparison, the world’s whitest paint reflects 98.1% of solar heat away from its surface.

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. 

Using this formulation to cover a roof area of about 1,000 square feet could result in a cooling power of 10 kilowatts, more powerful than the air conditioners used by most houses. At SXSW, researchers demonstrated the effects of the difference with two model barns sitting under direct halogen lights: one painted in commercial paint and one in Purdue’s white paint. Judges were able to compare thermometers reading the barns’ internal temperatures and to feel the difference in the roofs. The barn painted in Purdue’s technology consistently held cooler internal temperatures by 8-10 degrees Fahrenheit. The “whitest white” barn roof was also much cooler to the touch, prompting many surprised responses from judges and viewers. 

While Ruan’s original paint formula is massively efficient, it required a layer 0.4 millimeters thick to achieve subambient radiant cooling. The newer, thinner formulation can achieve similar cooling with a layer just 0.15 millimeters thick.  

The new paint also incorporates voids of air, which make it highly porous. This lower density, together with the thinness, provides another huge benefit: reduced weight. The newer paint weighs 80% less than the original paint yet achieves nearly identical solar reflectance – 97.9%, compared to the original formula’s 98.1%. 

Ruan and his team of researchers are currently working with the Purdue Research Foundation’s Office of Technology Commercialization for commercialization.  According to Ruan, “We are in discussions right now to commercialize it. There are still a few issues that need to be addressed, but progress is being made.” 

Ruan says the cost and production process is expected to be similar to commercial paint, which they’ve kept in mind from the beginning so that it would be accessible when it’s ready for market.

Patent applications for this paint formulation have been filed through the Purdue Research Foundation Office of Technology Commercialization. For further discussion on this intellectual property, contact and reference code 2022-RUAN-69542. This research was supported by the National Science Foundation with Award No. 2102645, and Andrea Felicelli was supported by a National Science Foundation Graduate Research Fellowship. The research was performed at Purdue’s FLEX Lab and Ray W. Herrick Laboratories and the Birck Nanotechnology Center of Discovery Park District at Purdue.

Writer/media contact: Trevor Peters,

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