PITTSBURGH - The next big thing in green-building design might be to turn an existing idea on its side.
PNC Financial Services Group Inc. recently installed a "green wall" the size of two tennis courts on one side of One PNC Plaza, the company's headquarters in downtown Pittsburgh.
Like green roofs, green walls are covered in vegetation, providing natural insulation and removing air pollutants. PNC estimates it will be 25 percent cooler behind the wall than the ambient summer temperatures.
Green walls also can be visually engaging.
The PNC wall features more than 15,000 ferns, sedum, brass button, and other plants that create a swirling pattern in varying hues of green above the company's logo. They are divided among hundreds of 2-by-2-foot aluminum panels that were anchored onto the building's frame after part of the granite facade was removed.
"We think it's the right thing to do for our community, for our customers and our shareholders," said Gary Saulson, head of corporate real estate for PNC. "We wanted to add greenery to an area that didn't have any. . . . We really view the green wall as public art."
Steven Peck, president of Green Roofs for Healthy Cities, a Toronto industry association, said interest in green walls was growing, though the group has not kept statistics. He estimated that green-roof installations have increased about 30 percent a year over five years.
Green Living Technologies of Rochester, N.Y., designed the wall at PNC. Chief executive George Irwin said the company also has installed walls in New York City, Los Angeles, Chicago, and Seattle.
PNC bills its green wall, which covers nearly 2,400 square feet, as the largest in North America. PNC officials declined to give a precise estimate of its cost. Irwin said that, on average, green walls cost about $100 to $125 per square foot.
The structure at PNC requires 15 minutes a week of watering during peak growing season - less in winter - provided through the building's plumbing system.
