absorb precipitation rather than letting it flow down a storm drain. They also support biodiversity, improve air quality and act as a carbon sink.
Green roofs have long been popular in Europe for more than 30 years, cities like Stuttgart Germany have millions of square feet of green roofs comprising 20 to 25 percent of the city’s flat roofs. Overall approximately 10 percent of the roofs in Germany are green. Cities such as Stuttgart and Copenhagen have mandated green roofs on most new construction. Now Toronto Canada has also introduced such mandates.
A 2005 study calculated that if 75 percent of the flat roofs in Toronto were green, it would save the city $37 million a year on storm water management, energy bills, and costs related to urban heat island effects.
Green roofs are also seeing tremendous growth in cities like Chicago, Portland, Manhattan and Washington DC, which has set a goal of 20 percent green roof coverage by 2020.
According to Green Roofs for Healthy Cities, an industry association, roughly 10 million square feet of green roofs were built in 2009, compared to a million in 2004.
As reported in Planet Save, in 2010, despite a very weak economy, the U.S. green roof market grew 30%. Approximately 8-9 million square feet of green roofs were reportedly added last year, largely in large cities like Chicago, New York, and Washington, D.C. that have implemented good green roofing policies.
According to the results of Green Roofs for Healthy Cities (GRHC) 2012 Annual Industry Survey of Corporate Members the green roof industry grew by 115 percent over the course of 2011, up significantly from 28.5 per cent growth recorded in 2010,” said Steven W. Peck, GRP, President of GRHC.
Although green roofs have expanded exponentially in the US, there are still “huge opportunities for expansion,” said Steven Peck, Founder and President of Green Roofs for Healthy Cities.
The major obstacle to the spread of green roofs is the initial cost, which can be anywhere from $15 to $35 per square foot. Although green roofs are two to three times the cost of a non-green roof, they last two to three times as long as conventional roofs.
The growth of green roofs makes sense from an environmental and an economic perspective. Although Chicago is a city that has built up its green roof infrastructure without government incentives, tax abatements, and regulations, such government support will help green roofs to expand even further.
© 2012, Richard Matthews. All rights reserved.
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