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.
This.
Do you know what also helps combat global warming? Higher albedo, the reflectivity of the Earth’s surface.
The reason why scientists have been crapping all over the news about how bad the polar ice caps melting will be is because it’s lowering the Earth’s albedo.
Sea water = DARK = ABSORBS SUNLIGHT & RETAINS MORE HEAT.
Ice & snow = PALE = REFLECTS SUNLIGHT & HEAT AWAY FROM THE PLANET.
Not with 100% efficiency in either case, but it has a massive impact.
This is literally why, when I owned my own home, I got a metal roof that was white, to reduce the heat coming into my house on hot summer days.
You know what’s dark and raises the temperature in cities & towns? Asphalt. Tarmac. Whatever you wanna call it, it’s dark and it absorbs and retains heat in an area. So do composite roof tiles, since for the most part they’re medium gray to dark gray (and sometimes other colors, but in general they’re dark).
Now, would I recommend this whitest-of-white paints for Alaska? Maybe not. Sunlight thermal energy is actually pretty important up there for most homes & businesses. But would I recommend it for places between 30 degrees north and south of the Equator, where heat is a genuine year-round concern? And in hot locations such as Texas or Arizona? In a heartbeat!
(via durnesque-esque)
