Paints that reflect infrared light to reduce heat absorption
AkzoNobel Deco’s “Keep Cool” technology pays off
In some places of the world, temperatures above 40 degree Celsius in the summer are common. That means even a thick-walled building will heat up like an oven, and air conditioners work overtime. AkzoNobel Decorative Paints has developed exterior wall paints that reflect more infrared light to reduce heat absorption and reduce energy consumption.
A research program in the UK to explore strategies to increase the solar reflectivity of exterior paints has already led to the development and launch of Dulux Weathershield SunReflect exterior paint in India and Dulux Weathershield KeepCool exterior paint in Singapore and Malaysia.
Normally IR radiation is absorbed through the paint and transferred to the interior of the building through conduction. Tests conducted by the Center for Energy Studies and Research, an Indian government agency, showed the new paints reflect up to 90 percent more infrared radiation than comparable exterior paints. When two identical panels were placed in the sun, measurements indicated that the surface temperature of the panel coated with SunReflect™ was up to five degrees Celsius lower than a panel painted with the same shade of a competitive product.
With the SunReflect technology, the interior will be considerably cooler, and that can actually lead to significant power savings on air conditioning. According to Building System and Diagnostics Pte. Ltd., an independent consultancy in Singapore, energy savings may be as much as 10 percent for a typical 15-story building and 15 percent for a bungalow.
About half of all sunlight is in the infrared spectrum, so the main focus of the research was to eliminate pigments that absorb IR radiation. The approach taken was to increase solar reflectivity by carefully selecting the best combination of pigments. Easier said than done however; you have to reformulate the paint in order to achieve the same shade. Getting the same color with alternative pigments required clever science, aided by some pretty sophisticated predictive software.
The idea that paint is just something to slap on a wall to add some color may soon be rather passé – AkzoNobel’s coatings scientists are hard at work exploring the potential of paints that will extend their functionality far beyond their traditional decorative and protective functions.