Fall 2009

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A Mile-High View of Green Roof Technology

Alumna Jennifer Bousselot conducts research on a green roof installed on the new Environmental Protection Agency (EPA) Region 8 Headquarters building in Denver. The PhD candidate at Colorado State University says, "A rooftop garden is built for beauty. A green roof is built for great utility and environmental benefits."

From her mother's garden and father's cornfields near DeWitt, Iowa, Jennifer Bousselot has come up in the world. Literally.

High above downtown Denver, the ISU alum conducts research on a green roof installed on the new Environmental Protection Agency (EPA) Region 8 Headquarters building. Over the parapet wall, she can see the front range of the Rockies. "It's a view like none other," she says.

A Ph.D. candidate in horticulture at Colorado State University, Bousselot ('01 plant health and protection, '03 MS sustainable agriculture) is the "plant person" on the EPA grant-funded research team studying the green roof.

Sedums are the popular, common choice for green roofs. Bousselot's research injected some native diversity into the mix. She selected a handful of Colorado species she believed would take to the shallow, well-drained green roof, including nodding onion, small-leaf pussytoes and brittle pricklypear. "The big deal is whether they can overwinter. So far, all but one have done very well."

Because roofs are engineered for building requirements, not necessarily for nutrient-holding and water-holding capacity, she also studies how to improve growing media for plant performance. The project examines the effects adding varying amounts of zeolite, a volcanic mineral with an affinity for hanging on to nutrients.

Sometimes Bousselot, who's worked for Colorado State Extension's Master Gardener program, has to provide science-based education for those who expect a lush paradise above their heads.

"A rooftop garden is built for beauty. A green roof is built for great utility and environmental benefits. The benefits include managing stormwater to dial down the intensity of runoff. It moderates temperatures to address cities" heat island effect - buildings soaking up heat. And it protects the roof membrane, extending its useful life by two or three times."

From her research elevation, Bousselot is amazed by the acres of rooftops she sees. "There's a lot of dead space that could be turned into something useful. City people constantly talk about a disconnect with nature. Maybe there's space above them that could help them reconnect."

Everything she knows about the science of plants began at Iowa State. "I'm honest when I say people are always impressed by that. ISU has a phenomenal reputation." Every day the lessons she learned from ISU's Deb Muenchrath, an agronomy faculty member who died in 2006, come into play. "Deb focused me. She was an incredibly inspirational and influential mentor."

For Bousselot, "green" in the broader sense is about choice. "Green means trying to be truly sustainable, to be conscious of the choices and decisions you make. It's about people trying to be environmentally conscious."

Her own choices have lifted her. Up on the roof, it's peaceful as can be (as the song goes).

"It's surprisingly quiet. You just hear the wind," Bousselot says. "Kind of what you'd imagine standing over an Iowa cornfield."

STORIES online extra:

• ISU's first green roof on the Design Center
• CSU's green roof project