Dark-colored roofs are major heat absorbers, making buildings harder to cool, which requires more energy. For years now, the idea of white roofs has been promoted as a way to cut building energy demand, but for some, darker-colored roofs are just more aesthetically pleasing.
For those people, researchers at Oregon State University have found a solution -- an environmentally-safe "cool blue" pigment that has darker tones, but reflects a huge chunk of infrared heat that could be used in energy-saving coatings for buildings.
“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.
“The more we discover about the pigment, the more interesting it gets. We already knew it had advantages of being more durable, safe and fairly easy to produce. Now it also appears to be a new candidate for energy efficiency.”
The compound, which has now received patent approval, was discovered about three years ago when OSU scientists were studying materials for their electrical properties. Researchers noticed that some manganese compounds came out of a 2,000 degree Fahrenheit oven transformed into a beautiful blue, which they figured out was due to an unusual “trigonal bipyramidal coordination” of their molecules that changed when exposed to extreme heat. This discovery led them to develop the blue pigment.
The material is now being considered for various commercial applications that could see it applied to roofs and walls of buildings to increase energy efficiency. Widespread use of reflective coatings, like what this "cool blue" pigment could be used for, could reduce the heat island effect in cities, lower peak energy demand, and reduce air pollution due to lower energy use and power plant emissions.
“We’re seeking licensing partners for this invention right now,” said Mary Phillips, associate director of the Office for Commercialization and Corporate Development at OSU. “We believe it can contribute to new energy efficiency solutions around the world.”