New course at Iowa State digs into green roofs


Jennifer Bousselot is teaching an online course on the design, installation and maintenance of green roofs. Larger image. Photo by Tom Slabe.

AMES, Iowa – A new online course beginning Sept. 3 at Iowa State University will offer up the dirt on green roofs, the high-rise gardens that are fast becoming fixtures of U.S. skylines.

The one-credit, eight-week course will cover the design, installation and management of green roofs and will be taught by Jennifer Bousselot, a lecturer in horticulture. The online course will be open to anyone, and those interested may register online, Bousselot said.

She broadly defined green roofs simply as vegetation on elevated surfaces that help to alleviate some of the environmental difficulties inherent in heavily populated cities. For instance, she said rain that falls on city concrete tends to create rapid runoff, but green roofs filter rainwater and slow down peak flows.

Pavement also absorbs heat during hot and sunny weather, pushing roof temperatures to 170 degrees. But plants on green roofs mitigate some of the trapped heat, which lowers both utility and maintenance costs, Bousselot said. The online course will cover the basics of green roofs, including how they’re designed and maintained. The curriculum also will include case studies of real green roofs.

“This will be a good place for people who are unfamiliar with green roofs – and even for people who already have some familiarity with the topic – to discuss and learn more,” she said. “Green roofs are in cities across the country, and it’s a trend on the upswing that isn’t going away.”

Modern green roofs first took root in Europe about 40 years ago, and they’ve been springing up in U.S. cities in recent years. She said Chicago’s City Hall boasts rooftop gardens, and the rest of the city has followed suit. Chicago now has around 6 million square feet of green roofs, Bousselot said. Portland, Oregon, has adopted green roofs as part of a strategy to reduce the runoff of storm water, she said.

They can also be found dotting the landscape of the Iowa State University campus.

Kerry Anne Dixon, a facilities project manager and coordinator for sustainable design and construction for ISU Facilities Planning and Management, said there are nine green roofs at Iowa State that range from the King Pavilion in the College of Design to a smaller one atop a bus stop near Coover Hall, and Dixon said the university plans to install another green roof in 2014.

She said Bousselot’s course is taking off at an opportune time as interest in green roofs among students has grown in recent years. The idea to plant a green roof on the Memorial Union, for instance, originated with a group of horticulture students, she said.

“We have a generation of students right now who are interested in sustainability and green ideas, and it’s important that we support them,” Dixon said.

Bousselot will teach the course from Colorado after spending just over two years on campus from 2010 to 2012. During that time, she taught horticulture courses and served as the master gardener coordinator for ISU Extension and Outreach.