By: Deborah Johnson Wood
Vegetative roofs are increasingly popular in the push to build green, sustainable buildings. But do they really reduce storm water runoff and thereby prevent pollution from fouling our rivers and streams? Lab studies show green roofs work in principle; mockup systems prove it. But there are far fewer studies in the real world to prove their effectiveness.
Clinton Boyd, senior scientist at Sustainable Research Group is about to change all that.
Metro Health enlisted Boyd to conduct the first-ever three-year study of a green roof in a natural environment—on top of Metro Health's new Wyoming, MI hospital. Boyd will monitor the quantity of storm water released from the roof, and the effectiveness of the parking lot rain gardens - or bioswales - in removing pollutants from the runoff.
"With a conventional roof, the storm water picks up heat from the roof and pollutants as it runs across other surfaces," Boyd says. "The theory of a green roof is that it retains the rainwater, and over time, the plants use the water and release it through their leaves (evapotranspiration), lessening the quantity of storm water generated from the roof."
Boyd has installed a digital data management system to measure water discharge, and a weather station that calculates the amount of rain that hits the roof.
To test the bioswales, Boyd is designing a way to capture samples of storm water before and after it enters the bioswales. He'll test both samples for the same pollutants, such as, metals, greases, oils, nitrates, and phosphates.
At 48,000 square feet, the roof is the second largest green roof in Michigan. Ford Motor Company's Rouge Plant is the largest.
Source: Clinton Boyd, Sustainable Research Group
Deborah Johnson Wood is development news editor for Rapid Growth. She can be contacted at [email protected].
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