Green Roofs

The urban environment is an environment in crisis. Development shrinks the natural environment with impervious surfaces, mainly roads, buildings and parking lots, negating the processes that regulate natural environmental response to stress. This puts additional stress on the physical environment, watersheds and grey infrastructure. Ambient temperature rises during hot summer months, additional stormwater runoff occurs, and building energy efficiencies plummet. The interconnected problems of the urban heat island effect, stormwater management and inefficient buildings will be exacerbated by global warming. A green roof strategy can help mitigate these interconnected problems, and also produce many other benefits such as open space, cleaner air, food production, increased biodiversity and increased property values.

Issue 1

A green roof is a roof that bears vegetation. Over thousands of years, whether called green roof, eco-roof, living roof or sod thatch roof, the idea has been the same: A dynamic, living environment of plant material on a rooftop. If green roofs help reduce negative urban environmental impacts, why is everyone not installing them? Many people are not aware of them, and others are deterred by costs. Benefits can be difficult to measure because they are long-term economic and public benefits. Thus, while a green roof’s initial cost is about double that of a traditional roof (due to the design, engineering and installation costs), it will pay for itself over time in savings by avoiding replacement, and in lower heating and cooling costs over the life of the green roof. Public benefits include stormwater retention, mitigation of urban heat island effects, gains in building energy-efficiency and increased biodiversity, among others. These public benefits are not fully realized by the party bearing the cost of the green roof installation, thus they justify public intervention, such as public green roof policies.

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In 2000, a 20,300 square foot City Hall rooftop garden was installed, part of the City’s Urban Heat Island Initiative. In 2003, The Chicago Department of Planning and Development begin actively encouraging green roofs through their “green roof policy matrix”: any project that receives public financial assistance or is in a Planned Development or Lakefront Protection Ordinance Development has to contain certain design elements, including a green roof. In 2005, the Chicago Department of Environment began awarding $5000 grants to residential and small commercial building (less than 10,000 sq. ft.) owners who installed a green roof. Since 2005, 72 green roof grants have been awarded. Although the program has been exceptionally successful, it is no longer being funded because of City budget constraints.

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Although policy is important, creating awareness and promoting advocacy at the grassroots level is a vital step in progressing green roofs as an ordinary and accepted practice in the roofing industry. Green Roofs for Healthy Cities, a non-for-profit association, is working diligently in promoting green roofs throughout North America. Local chapters work within individual communities to promote and install green roofs while simultaneously educating people through a variety of means to the many benefits green roofs provide a community. Artist Maureen Hearty is making mini garden-friendly green roofs out of recycled materials to increase awareness about green roofs. Green roofs have entered the public discourse to the point that they can now be referenced in art and the artist can take for granted that the viewer is aware of concept of green roofs. Conversely, the use of green roofs in popular culture adds to the public knowledge of such things. The artwork below represents a potential for dialogue between what happens on a larger scale and a smaller, grassroots scale.

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Chicago has been the North American leader in green roof square footage because of the policies, advocacy and support at the grassroots level. Whether we continue to lead the nation depends on us. So too does our quality of life. A green roof strategy poses important questions: Do we agree? Will we educate? Who else will join our advocacy and what creative methods will they employ? ◊

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Sources:

Berkshire, Michael. Personal Communication, 14 March 2010.

Weiler, Susan K., and Katrin Scholz-Barth. Green Roof Systems: A Guide to the Planning Design, and Construction of Landscapes over Structure. Hoboken, NJ: John Wiley & Sons, 2009.