What is a ‘Green Roof’?

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As it has been mentioned in our Greenest Place in America article, the city is not known for its environmental friendliness.  But, this perception is  uninformed.  There is a great deal of work that has gone into making city life, and city planning, into a pursuit that is not only sensitive to the environment, but is actually active in addressing environmental issues like better air quality, greater energy efficiency,  and global climate change.

One method which has been in place for a number of years in urban settings  is ‘green roofing’.  But, what is that, exactly?

MEC´s green roof among othersGreen roofs  are designed to incorporate the physical placement of living vegetation into a building’s design, most often planted in soil that is bedded in the roof itself.  Green roofs are designed  to allow for self-contained growth, complete with drainage systems to sustain vegetation, and to manage storm water runoff.  They have a number of benefits which have an impact on the reduction of harmful factors and promotion of green building best practicees, such as:

  • Natural insulation which allows for greater energy efficiency and heat retention in winter months
  • Overall temperature reduction in summer season, reducing need for HVAC cooling systems
  • Reduction of rainwater runoff, and promotion of rain harvesting
  • Natural pollutant filters that contribute to better air quality
  • Natural filters that remove heavy metals in rainwater

The scale of green roof technology varies from farmhouses in Iceland that use green roofs to retain heat, to green roofs in the United Kingdom that incorporate them to provide greenery to urban dwellers who otherwise don’t have access to natural green space.  And some green roofing projects have been legislatively  mandated, as they are in Toronto, for many residential and industrial buildings.

Recently, a green roof was installed in one of the tallest buildings in the world, The Willis Tower in Chicago, formerly the Sears Tower.  And yet many other high-profile green roofs, like Chicago City Hall,  Canary Wharf In London, and the Dearborn, MI Ford Motor company plant, have shown that green roofs are viable elements in city planning and green building in a number of contexts.

Along with the other benefits of city life that make green living a matter of course (widespread public transit use, local consumerism that encourages walking and biking to access amenities, greater use of resources through apartment living, and more), green roofing is a green building technique that has been used for centuries in rural settings, but seems to be an indicator of where we should be heading in 21st Century urban development, too.

Although green roofing has its pros and cons, the benefits they present seem significant enough to hope that city planners, designers, and local politicians to take a look at the viability of roof gardens.



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