3M
Roof Shingles
Granules have been a part of our business since the 1930s,” says Gayle Schueller, 3M’s chief sustainability officer. “This is not a new business to be in, and it’s not a new material for us.” Traditionally, granules are used in roof shingles construction to coat rooftops and provide an extra layer of protection from UV rays.
They also help buildings remain cool and less dependent on air conditioning. They also make roofs more fire-resistant. Around 10 years ago, 3M developed “cool roof shingles” granules that reflect sunlight and help buildings comply with roofing standards like the 2014 Los Angeles ordinance mandating new residential projects be built with additional rooftop insulation to keep them cool.
Instead of reflecting the sun, though, 3M’s new smog-reducing granules use it. The photocatalytic coating on these granules, designed for asphalt roof shingles, is activated by the sun’s UV rays. That generates radicals that bind with the chemical compounds in smoggy air and transform them into water-soluble ions that eventually wash away.
3M Testing
While 3M conducted its own internal testing of the granules, it also sent samples for external validation to Lawrence Berkeley National Lab, which evaluated how effectively the granules absorbed different gases and pollutants. They found that an average-sized roof coated in granules removes around as much pollution from the air as three trees could.
“When we innovate, we start with an understanding of where there is a problem, and we identified the issue of smog in cities,” Schueller says. Around 10% of 3M’s 90,000-person staff are scientists, she adds, and they collaborated on both developing the photocatalytic coating and testing its environmental impacts.
The runoff from the ions, they found, does not contribute significantly to water quality issues–the impact is minimal, Schueller says, and the smog would’ve infiltrated the water from the air anyway if it hadn’t first been absorbed by the roof shingles granules.
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