As springtime progresses and temperatures rise, one rooftop at Penn is getting a little greener.

The rooftop at Kings Court English College House is the University’s first extensive green roof, in which a typical rubber membrane is replaced with a growing medium and plants. Completed late last fall, the plants were dormant over the winter, but now are beginning to flourish in the sunshine.

“The green roof is part and parcel of good design,” says Dan Garofalo, senior facilities planner in the Office of the University Architect.

In addition to any aesthetic benefits, the green roof offers several tangible ones as well. It retains or slows down storm water and helps to prevent excess water from flooding the city’s supply. Garofalo says that green roofs can also aid in keeping buildings cool in the summer by as much as 15 to 20 degrees on the top floors, and insulate the building from icy winds and below-freezing temperatures in the winter.

Vegetation also absorbs the sun’s UV rays, preventing the rubber roof membrane from quickly degrading. “The green roof actually protects the actual roof membrane so it lasts much longer—40 to 50 years, at least for the parts that are covered,” says Mariette Buchman, director of design and construction for Facilities and Real Estate Services.

The greenery also provides a habitat for beneficial birds and insects and reduces what’s known as the “heat island effect,” where cities with little to no foliage are often 7 to 10 degrees hotter in temperature than leafy outskirts.

The plantings, which stretch around the perimeter of the roof, are comprised of sedums—a high-altitude, hearty plant—and drought-resistant grasses planted in S-shaped curves. The plants sit in a soil medium that lies atop drainage, root-permeable and, closest to the deck itself, waterproofing layers. This spring, crews will likely replace about 10 percent of the plants that did not survive the winter. “We’re very encouraged that there’s going to be a lot of growth over this spring and summer,” says Buchman.

The green roof at this College House, managed jointly by Housing and Conference Services and Facilities and Real Estate Services, is a good fit. Not only was Kings Court English in need of a roof repair at the time of the green roof installation, but the house is known for its numerous green thumbs: The lush courtyard garden has garnered an award from the Pennsylvania Horticultural Society and the house offers a living-learning program, where a few students live in a “biosphere” and embrace all things green.

Jorge Santiago, an associate professor of engineering in SEAS and faculty master of the house, says the small succulent plants will brighten up the roof top deck, and offer a pleasant view to students at work (or play) in the glass-enclosed rooftop cafe. “It will be just a wonderful green color at the chartreuse end of the spectrum,” he says of the plants. “And it will be a great way of keeping that floor fresh during the summer and warm during the winter.”

Garofalo says this project fits squarely in with Penn’s focus on sustainability, and special attention to greenhouse gas reduction. With President Gutmann’s signing in February 2007 of the American College & University Presidents Climate Commitment, the University is drafting an action plan by 2009 to achieve long-term climate neutrality. Garofalo says groups are exploring ways to do this in transportation, energy and utility recycling and buildings and grounds, including recommendations for new building standards. He adds, “green roofs are definitely a component of that.”

Originally published April 24, 2008