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Monday, 10 August 2020
Raw materials & technologies, Raw materials, Coatings pigments

Cool roof! Thanks to a blue pigment

Wednesday, 22 August 2012

Just by chance, but even more impressive: A blue pigment reflects about 40 % of infrared heat.

Blue might now become common for energy saving pigmentation for roofs

Source: LianeM/Fotolia

Blue might now become common for energy saving pigmentation for roofs

Source: LianeM/Fotolia

The researchers call it "cool blue". It is a compound of a new type of durable, environmentally-benign blue pigment discovered at Oregon State University (OSU).

The compound, which has now received patent approval, was discovered about three years ago almost by chance, as OSU scientists were studying some materials for their electrical properties.

Some manganese compounds came out of a 2,000 degree Fahrenheit oven transformed into a beautiful blue, which researchers later determined was due to an unusual "trigonal bipyramidal coordination” of their molecules that changed when exposed to extreme heat.

Huge reflection performance

Its potential use to help reduce heat absorption on the roofs and walls of buildings – which is an evolving field of considerable interest in warm regions where cooling is a major expense – adds another role for the material, which is now being considered for various commercial applications. Therefore "cool blue" might become important for new approaches to save energy in buildings.

In general, any darker color of the type often used for roofs, houses, automobiles or other applications will tend to absorb more heat. But some compounds, like the one discovered at OSU, have dark tones but also the ability to reflect heat in the infrared spectrum, which is responsible for most of the heat energy absorbed from sunlight.

"This pigment has infrared heat reflectivity of about 40 percent, which is significantly higher than most blue pigments now being used,” said Mas Subramanian, an OSU professor of chemistry who discovered the compound.

Environmental-friendly construction building

"Cool roofing,” in which paints are used to reflect significant portions of the sun’s heat and thereby reduce cooling costs, is an important new trend in "green” construction and energy efficiency, experts say. Such reflective coatings also are more aesthetically pleasing, have less thermal degradation, reduce the "heat island” effect in cities, lower peak energy demand, and reduce air pollution due to lower energy use and power plant emissions.

Research will continue at OSU on the heat reflectance capabilities of the new compound and the underlying molecular structure responsible for it, scientists said.

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