An interesting article popped up via LinkedIn today about the green roof trend. From the Engineering News Record:
'Green roofs are gaining acceptance in dozens of countries, joining
other forms of green infrastructure that are being used to mitigate
environmental problems of urban centers.
For example, vegetated
roofs “are very good at managing stormwater. Most extensively planted
green roofs will hold the first inch of rainfall and slow any additional
rainfall, thus reducing peak flows and lowering the stress on combined
sewer overflows,” says Steven Peck, founder and president of Green Roofs
for Healthy Cities (CRHC).
The group is a professional
association with both corporate and individual members, ranging from
large manufacturers to contractors, nurseries, landscape architects,
structural engineers, roofing consultants and horticulturalists.
"Stormwater management has been a driver [of green roof construction] in
the U.S.," adds Peck.
"The Environmental Protection Agency is
working on rulemaking for municipal separate stormwater sewer systems
(MS4s). It's very clear there is going to be a very significant green
infrastructure component (green roofs and green streets)," says Nancy
Somerville, executive vice president of the American Society of
Landscape Architects.
Many cities throughout the U.S. and Europe
have green-roof mandates or incentives in place. Stuttgart, Germany,
requires green roofs on all new flat-roofed industrial buildings. In
2007, Pittsburgh enacted an law establishing stormwater volume reduction
standards for properties greater than 10,000 sq ft, including on-site
retention of the first inch of rainfall through any combination of
infiltration, evapotranspiration and rainwater harvesting. Portland,
Ore., requires new city-owned buildings and existing buildings in need
of a roof replacement to install a green roof on at least 70% of the
roof area.
Green Roofs for Healthy Cities' annual survey of its
corporate members found that the green roof industry in the U.S. and
Canada increased 115% between 2010 and 2011. The annual growth rate is
derived by averaging the square footage of green roofs installed by a
representative sample of corporate members.
"Increasing numbers of
building owners in the public and private sectors are recognizing they
can design, build and maintain green roofs profitably with a good return
on investment," says Peck.
"Green roofs have a higher cost up
front, but the payback over time is significant, not just in energy
savings. It's protecting your roof membrane—you can skip one or two or
three roof replacement cycles," says Somerville.'
The full article from ENR can be found here. Check out more great photos of the largest green roof projects in the world:
http://enr.construction.com/buildings/sustainability/2012/0709-10-largest-green-roofs.asp
It's an encouraging trend to see cities across the US, including Oakland, promoting urban greening strategies to mitigate serious environmental issues, including the urban heat island effect and waterway contamination from stormwater runoff. Cities may never be carbon sinks, but green roofs are just one example of the many creative ways urban areas are becoming more climate conscious and aesthetically pleasing places to live.