Engineers at Purdue University have created the whitest paint ever to coat buildings with it so that they will one day cool enough to reduce the need for air conditioning.
According to Xiulin Ruan , professor of mechanical engineering and lead author of the study describing this finding:
If you used this paint to cover a ceiling area of approximately 1,000 feet (333 meters) square, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners that most homes use.
Paints on the market that are designed to reject heat reflect only 80% to 90% of sunlight and cannot make surfaces colder than their surroundings .
But the researchers believe that this white may be the closest equivalent of the blackest black, "Vantablack," which absorbs up to 99.9% of visible light. The new whiter paint formula reflects up to 98.1% of sunlight , compared to 95.5% of sunlight reflected by researchers’ previous ultra-white paint, and sends infrared heat away from a surface at the same time.
Two characteristics give the painting its extreme whiteness:
- paint’s very high concentration of a chemical compound called barium sulfate that is also used to make photographic paper and cosmetics white.
- Barium sulfate particles have different sizes in paint. The amount of light that each particle scatters depends on its size so a wider range of particle sizes allows paint to disperse more than the spectrum of sunlight.