Researchers create ultra-white paint that can cool your home​

The new BaSO4 paint can cool 4.5o C below the ambient surroundings.

Researchers from Purdue University in the U.S. have developed an ‘ultra-white’ paint, which when painted onto buildings, can reflect the sunlight falling on them and lower the temperature indoors by 4.5o C than the surroundings. They say this can alleviate global warming on two counts; by reducing carbon emissions from air conditioners, and driving the sun’s incoming heat away to outer space – a principle called radiative cooling. The able to achieve this by adding Barium sulfate(BaSO4) to acrylic paint, imparting a reflectance of 98.1%. This marked an improvement over the team’s earlier work last year that made use of Calcium carbonate(CaCO3) as a filler material to produce a paint that boasted 95.5% reflectance. To lend context, heat-reflective commercial white paints in the market possess reflectance ranging from 80 - 91%. But they are unable to maintain a temperature consistently lower than the surroundings throughout the day. Speaking to The Hindu over email, Xiulin Ruan, who headed the team, says “Our previous CaCO3 paint could consistently cool 1.7 o C below the ambient temperature. The new BaSO4 paint can cool 4.5o C below the ambient surroundings.” The findings were published recently in the journal .