Purdue’s ‘world’s whitest paint’ wins 2023 SXSW Innovation Award - Purdue University News
Why this is so important:
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%.
This could be an important piece in fighting global warming. Imagine if the city of New York City repainted all the skyscraper roofs with a paint that cools down buildings.
