Crowned with "green roofs," Swarthmore's new residence halls have attracted widespread attention for their pioneering approach to environmental sustainability.It took a generous alumnus, an inventive horticulturist, a determined professor of engineering, and a little bit of luck to make it happen.
Green roofs use vegetation to provide energy-saving insulation and manage storm water runoff. Swarthmore's first green roof, a turnkey system installed in 2003 on a shed behind Papazian Hall, became the focal point of an environmental studies course taught by engineering faculty Carr Everbach and Art McGarity, along with Jeff Jabco, director of grounds and coordinator of horticulture for the Scott Arboretum. They began to consider green roofs for other campus buildings.
Watch the Scott Arboretum's videos about the building of the green roof on Kemp hall.
Luckily, no extra cost was involved, and the engineer made last-minute changes to the specifications. "If I'd waited one more day," Everbach said, "it would have been too late."
Now, Swarthmore had a design that would support a green roof. The next step was to install it. Rather than use another turnkey package, the College acted as its own general contractor, producing both a cost savings and some innovative thinking.
Swarthmore's green roofs are constructed in layers, including fabric to protect the roof structure and provide filtration, a drainage layer, a growing medium, and a crowning layer of plants. Sedum is preferred because it thrives in rooftop conditions: high temperatures, no shade, wind, and drought.
The cost of planting sedum by hand is considerable. Encouraged by a consultant, Jabco simply spread sedum cuttings across the roof instead. "After about three weeks, the cuttings took root," he said. "After a few months, we had plants."
Everbach turned his attention to the drainage layer. Some of the best drainage materials come from Germany, where green roof technology is advanced, and have to be imported—at no small expense. Instead, Everbach said, "I thought Solite® might work. So I called John Roberts."
John Roberts '39, an engineering major, and his wife, Jane Martin Roberts '39, are long-time supporters of engineering at Swarthmore. In 1947, he founded the firm now known as Northeast Solite Corporation. Using shale excavated near New York City and Lexington, Kentucky, Northeast Solite manufactures a lightweight aggregate which is formed into blocks and used in construction. It had also been used successfully in another green roof.
"We said 'yes' to Carr," Roberts said, "because we wanted to make a meaningful contribution to Swarthmore that would also provide a learning experience."
He sent a bag of Solite® to Everbach, who in turn sent it to Germany to be tested against the high-quality products used there. The verdict: Solite® was better. The company donated truckloads, and the project was a go.
The granular Solite® makes the roof looks like "gray frozen peas with plants growing up between them," Everbach said. "It provides good drainage and the right level of moisture. It's light in weight, so it doesn't add much to the load on the building."
In August 2008, as the finishing touches were being placed on the David Kemp Residence Hall, Everbach placed another call for another donation of Solite®.
"I called John on a Thursday, and I said, 'Can you deliver it by Monday morning?" Everbach said. "He did. John is an incredible patriot for the College."
Today, Jabco is a leading expert on green roofs, and Alice Paul and David Kemp halls serve as rooftop classrooms for architects, designers, horticulturists, and roofers from around the country.
No fewer than 695 have toured the roofs in 2008 alone.
Northeast Solite has a burgeoning business in green roofs (and in another product, a curing agent that makes concrete more sustainable). In part, Roberts credits his years at Swarthmore.
"The impetus came from Swarthmore, which gave me a unique opportunity to study engineering in a liberal arts environment," he explained. "It helped instill in me the desire to leave this world a better place than it was when I came into it 90 years ago."