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More city buildings cultivate savings by covering roofs with plants
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Part of the green roof at Carnegie Mellon University's Posner Center. -
This green roof can be found atop the Heinz 57 Center on Sixth Avenue, Downtown.
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Perhaps the most interesting parts of some Pittsburgh buildings are best seen from the roofs.
Actually, they are the roofs.
Green roofs, specifically, covered with plants growing in absorbent material to reduce storm water runoff, cut energy use, cool the urban core and lengthen the lifespan of the roof itself.
They look good, too, but most are not visible to the public except when gazing down from a higher floor of a nearby structure.
Green roofs got a big boost to their public image last week when Allegheny County Executive Dan Onorato announced plans to install one on top of the County Office Building as a demonstration project. The county will keep half the roof as it is and measure the difference in storm water runoff between the two sides.
It will be at least the third green roof Downtown, joining the Highmark Blue Cross/Blue Shield building at Fifth Avenue Place and the Heinz 57 Center (formerly Gimbels), which was featured in the 2009 Greenroofs of the World Calendar by Greenroofs.com.
Pittsburgh's biggest cluster of green roofs is in Oakland: six on the Carnegie Mellon University campus and one more under way; one at the University of Pittsburgh and two in the planning stages; and one at Phipps Conservatory.
There are also green roofs on the Giant Eagle Market District building in Shadyside, the Children's Museum on the North Side, the Pittsburgh Zoo & PPG Aquarium in Highland Park and the new Children's Hospital building in Lawrenceville.
Conservation Consultants Inc. on the South Side also installed a green roof as an educational and demonstration project on the four-story building it occupies. Several private homes have green roofs as well.
"Pittsburgh is really coming along and could be a national leader on this issue," said Janie French, watershed programs manager for 3 Rivers Wet Weather Demonstration Project, created in 1998 to help Allegheny County municipalities address the deteriorating sewer infrastructure and comply with the Clean Water Act.
"Over the last 10 years there have been quite a few green roofs installed," she said, "and there are going to be a lot more in the future. Some are in the planning stages right now."
These spaces are not generally intended as parks or gardens where people go to soak up nature, although some may also serve that function. Rather, they are built to soak up rainfall that otherwise floods antiquated, overtaxed sewage systems, a growing problem in American cities. What the green roofs don't absorb (usually they take in 60 percent to 70 percent of the rainfall) they delay, slowing the flow to a more manageable amount.
Green roofs also insulate against ultraviolet rays that cook the temperatures inside and out, cutting heating and cooling costs and counteracting the "urban heat island" effect that makes cities warmer than surrounding areas.
It's all part of a growing movement to mitigate some of the environmental damage caused by building on green spaces that once helped the earth maintain its ecological balance. Controlling storm water overflows that pollute rivers and streams with raw sewage is a major goal. So is combatting global warming by reducing energy consumption.
In an interesting twist, the first green roof Downtown, installed in 2001 on the penthouse terrace of the Heinz 57 Center, was never intended to address environmental concerns. That it turned out to do so was just a happy coincidence.
"This was before many people were thinking that way," said Jess Wieland of McKnight Properties, the building's landlord.
"Heinz wanted to put its executives up there on the 14th floor," Mr. Wieland said. "They would have been looking out from their glass windows onto a black rubber roof and a nine-foot brick parapet. The sole purpose for us in putting in the roof garden was aesthetics, to give the heavy hitters something to look at."
Eight years later, the Heinz roof is 15,000 square feet of flowering meadow, a colorful riot of 18,000 plants growing in felt-like fabric, drainage and growth media. And it never has to be watered.
"It absorbs a lot of water, and it will far outlast the life of a traditional roof," said Mr. Wieland. "But that's not why we did it. Any environmental benefit wasn't even a selling point at the time."
The cost was $250,000, he said, or about six times the cost of replacing a plain rubber roof. The space also has some patio seating so that executives can sit outside in the garden.
An even larger green roof is atop the fourth floor of Highmark at Fifth Avenue Place, an L-shaped surface along Fifth Avenue Extension and Penn Avenue. Planted in June 2008, it's now almost a year old. And unlike its predecessor, its planners had ecological concerns at the front of their minds.
"The building was 20 years old, and we were looking to replace the roof," said Phyllis Barber, Highmark's sustainability coordinator.
"We researched the benefits of green roofs, and this was a good opportunity to try it."
At 22,000 square feet, the Highmark green roof holds 180 tons of growth media -- mostly light volcanic rock and ash -- and 25,000 plants, including 12 types of sedum, or drought-resistant succulents that absorb 60 percent to 70 percent of the rainfall.
The plants, including day lilies, cone flowers and dianthus, are hardy perennials that create a flowering meadow with different colors in spring, summer and fall. And, as with the Heinz building, there's no watering necessary.
The roof is visible, but not accessible, from several of Highmark's adjacent glass-walled conference rooms.
A conventional roof lasts about 20 years, Ms. Barber said, but a green roof lasts twice as long because it is protected from the ultraviolet rays. And the insulation cuts heating bills in winter and air-conditioning bills in summer.
The roof cost $600,000 to install. Highmark figures it saved $330,000 in 2008 from all its green initiatives but has not broken out which portion of that was from the roof.
"We're hoping our roof will be a catalyst for other green roof development Downtown so we can all realize the benefits together," said Ms. Barber.
Carnegie Mellon University art professor Bob Bingham and his students were involved in designing the campus green roofs.
"Hamerschlag Hall is the best model," he said of the school's first effort, in 2005. "Two-thirds of the plants are sedums, with eight to 10 species. It's almost at ground level and can be seen by people walking by."
Mr. Bingham ticked off the other campus locations: Posner Center, Porter Hall, Mellon Institute and Doherty Hall. In addition, he said, workers are now loading the growth media onto the roof of the new Gates Center for Computer Science.
At Pitt, the green roof is on Benedum Hall, which houses the engineering school. University spokesman John Fedele said another is planned for the Benedum plaza and one more for the new addition to the K-8 Falk Laboratory School on Allequippa Street.
"The concept is really catching on in a short amount of time," said Ms. French. "It's to everyone's benefit. When we keep storm water out of the sewers the cost of rehabilitating them decreases."
The green roof movement began in Germany in the 1970s and migrated to North America in the 1990s, said Steve Peck, president of Green Roofs for Healthy Cities, a nonprofit industry association headquartered in Toronto.
The first North American green roof is believed to have been in Portland, Ore., where a city engineer built one on his garage to see what would happen. About the same time, Chicago Mayor Richard Daley toured Europe, where green roofs were becoming increasingly popular (they now account for billions of square feet). Having just been through a brutal summer of power failures, Mr. Peck said, Mr. Daley decided to put a green roof on city hall and began offering inducements for others to follow suit. That city, he said, is aiming to have 6,000 green roofs installed by 2020.
As interest grew, so did Mr. Peck's organization -- from six companies to 1,700, including individuals and corporations. Members, he said, installed an estimated 5 million to 6 million square feet of green roofs in North America in each of the past two years.
"We're seeing a growth rate of 30 percent," Mr. Peck said. "Cities are recognizing the public benefits and governments are providing more financial incentives. New York City has a tax abatement program of $100,000 per project, and there's a similar program in Philadelphia."
One other sign that the movement is getting serious: Green Roofs for Healthy Cities has devised the first-ever exam for certifying "green roof professionals," to be administered at its seventh annual conference in Atlanta from June 3-5. The certification, Mr. Peck said, will establish best practices and help consumers find qualified professionals.
Ms. French of 3 Rivers Wet Weather said the main barrier to green roofs is cost, which varies greatly depending on the site size, location, materials and aesthetics.
"I probably get two or three calls a week asking where businesses and individuals can find funding," she said.
She's hoping some of President Barack Obama's stimulus package can be put toward green roof cost abatement, but in the meantime, the only available help is from state and federal programs such as the Pennsylvania Energy Harvest grants.
"There's no local incentive right now, but there could be," Ms. French said. "We have to look at how to create them.
"Pittsburgh is such a sports-oriented city. Wouldn't it be great if it put out a challenge to other cities to see who could do the most green roofs in the next five years? Maybe we could challenge Cleveland!"
First Published May 19, 2009 12:00 am
