Of
all the low-impact development measures available, green roofs are getting a lot of
attention these days. They’re a novelty in many ways—a garden eight stories in
the air is inherently more interesting to most people than, say, a bioswale.
In Chicago, which Mayor Richard
Daley has declared he wants to make America’s greenest city, there’s one on top
of City Hall, as well as on a couple hundred other buildings. Baltimore
is catching up, adding about 150,000 square feet of green roofs last year.
The process of constructing them
is also featured in a video, available on this EPA
web site, called “Green Jobs
for a Green Future.” The video is narrated by the White House special advisor
for green jobs, Van Jones, who is also the author of the book The Green
Collar Economy.
Are green roofs the most
cost-effective way to limit runoff and remove pollutants? Probably not, but the
cost depends on many different things: Whether you’re adding a green roof to an
existing building, whether you’re creating an extensive or an intensive green
roof, and perhaps which continent you’re on. They’ve been more widely used in
Europe than in North America, and the costs for constructing green roofs is
lower there; some people expect them to get cheaper here, too, as the techniques
and materials become more common. As William Hunt of North Carolina State
University noted in this article
from our
October 2008 issue, “It’s simply an economy-of-scale issue.”
In addition to their stormwater
benefits, green roofs can reduce heating and cooling costs of their buildings,
and, well, they look good. Companies that want to show their commitment to the
environment often choose them for their corporate offices. There are other ways
to earn LEED
credits and achieve many of the same goals, but green roofs are here to
stay. For more information and a useful Q&A, see the Green Roofs for Healthy Cities web site.