If one climbs through a third-floor window in the new Molecular Plant Sciences Building, one will arrive on the roof — a roof carpeted with short flowering plants and grasses: A green roof.
Brad Rowe, professor in the Department of Horticulture, was instrumental in getting the green roof installed last fall, and has been working with green roofs for about 12 years.
“When we first started doing this like 12 years ago, no one really knew what a green roof was.” he said. “And now I think most people do at least have some idea what a green roof is. And they’re becoming more and more common.”
Rowe became interested in green roofs when Ford Motor Company approached him when it was in the process of designing a 10.4-acre green roof for its Dearborn plant. The green roof there is among the largest in the U.S.
“They gave us good funding to get the platforms built and get some graduate students to start working on it to figure out how much storm water would they would save, what plants to use, what systems to use — we did all that, and we just kept going,” Rowe said.
Rowe has been doing research on green roofs using raised platforms in the Horticultural Teaching and Research Center, as well as on the roof of the Communication Arts Building and Plant and Soil Sciences Building. The Physical Plant has also has installed green roofs on Brody Hall and the new addition of Wells Hall.
“You can put almost any type of plant on a roof,” Rowe said. “There are roofs with trees and shrubs and that on it, but the media has to be very deep, like several feet.”
Those are known as intensive green roofs, but they are less common because they require buildings that are strong enough to hold that weight. Extensive green roofs, with six inches or less of media, are more common.
“The majority of the roofs have a lot of succulents like sedum, which can go for months without water,” Rowe said.
Green roofs are fairly popular in Germany, where 25 percent of the buildings in some cities have green roofs, Rowe said.
Green roofs help absorb or slow down water runoff, which prevents storm water and sewage systems from overflowing. They also absorb carbon dioxide from the atmosphere and help insulate the roof from rapid temperature changes that take place particularly during the summer. And because green roofs are insulated from temperature changes that can cause them to crack and leak, they can last two or three times longer than typical roofs, he said.
“A study we did on the roof here showed the heat flux was reduced up to 167 percent during the summer, and so that has an impact on the energy required to heat and cool that individual building,” Rowe said.
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