Will green roofs be the next hot trend? |
| By Cliff Bowden • Bankrate.com |
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If the term "green roof" evokes an image
of a few potted plants arranged tastefully on the top of a building,
then the time seems ripe to rethink that definition. Green roofs
may be the next hot trend to cool down the urban landscape and lower
the cost of controlling temperatures in the average suburban home.
Green roofs are generally categorized by one of two
forms. Extensive green roofs, also known as eco-roofs or low-profile roofs, are
made with a few thin layers of soil, are lightweight, relatively less expensive,
and require very little maintenance. Extensive green roofs are the correct choice,
the experts say, when the primary desire is for an ecological cover with limited
human access. Intensive or high-profile green roofs, on the
other hand, look like traditional roof gardens because a much wider variety of
plant material is usually included. They have soil depths ranging from 8 to 12
inches, with growth that can extend upward of 15 feet. They can include such architectural
features as waterfalls, ponds and gazebos. Their construction and maintenance
is much more costly.
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New
to the U.S.
Tristan Roberts, an executive with BuildingGreen
in Brattleboro, Vt., says that while interest in green roofs within the U.S. has
only taken root in the past decade, green roofs as a phenomenon have a long history.
"They go back for hundreds, if not thousands, of years,"
he says, "as sod houses in this country and as living roofs in Europe. The
modern equivalent has been around for quite a few decades and is much more prevalent
in Europe, particularly Germany." BuildingGreen, which
bills itself as an independent operation dedicated to distributing information
to building-industry professionals and policymakers, sees green roofs as one way
to improve the environmental performance and reduce the adverse impacts of traditional
buildings.
Bill Retzlaff, chair of biological sciences at Southern
Illinois University-Edwardsville and coordinator of the research
cooperative Green Roof Environmental Evaluation Network, or G.R.E.E.N.,
says the green-roof industry in the U.S. is very new. "While
Europeans have been doing them for a long time, our climate is different,
so there's not much useful data on their performance here."
The G.R.E.E.N. cooperative was established two years
ago to evaluate green-roof technology in the Midwest, says Retzlaff. In
addition to the university, members include several commercial suppliers
and Greenroofs.com,
an international resource and online information portal for the
green-roof industry.
"Our
longest-running project has been on the ground since September 2005," says
Retzlaff. "We now have seven specific green-roof projects at our field site.
We're evaluating storm-water runoff and temperatures, comparing those results
with the results we get with a flat membrane roof." While
green roofs don't necessarily require a lot of care, it's a misconception to suppose
that they will just take care of themselves. G.R.E.E.N. researchers are working
with systems that don't require a lot of maintenance, but there's no such thing
as a no-maintenance green roof. "You must water them
for the first 10 weeks or so," Retzlaff says. "They have to get established,
just like any other garden. And at minimum, you need to add some plants, fertilize
and weed a couple of times a year." | 
