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Green – arguably the biggest buzz-word in 2007. Green has been used in the context of food, fashion, travel and most notably in the design and construction of commercial and residential buildings.
The latest innovation in the world of green is green roofs–rooftops that are covered all or in part with vegetation and soil. The rooftop of a residential or commercial building includes a light weight growing medium (such as volcanic rock), a filter layer, a drainage layer, a root resistance layer and a waterproof membrane. Green roofs are often planted with drought-resistant plants such as sedums, grasses or wildflowers which grow in a six-centimetre thick layer of a growing medium. Winter green roofs are often composed of juniper shrubs that grow in a much thicker soil.
While a green roof certainly looks like it’s playing an important role in the protection of the environment, it’s doing a lot more than just that. Benefits of green roofs are being felt in industry, government, public space and private life – they beautify; they reduce the use of air conditioning in small buildings; they retain a large amount of storm water and keep it from inundating the city’s water-management system; they reduce air pollution; they cut down noise pollution; and create a refuge for insects and wild birds.
The green roof is a trend that has spread from Europe to North America, where cities like Chicago, New York, Toronto and Vancouver are all vying for the title of the greenest city. A relatively new trend in Canada and the United States, green roofs have been common in Europe for years, since the continent has embraced the technology required in its effort to combat climate change. This has been the direct result of government legislative and financial support, at both the state and municipal levels. Such support recognizes the many tangible and intangible public benefits of green roofs.
Unfortunately, at this early stage in the development of green roof technology, the benefits of green roofs are poorly understood and the North American market remains immature, despite the efforts of several industry leaders.
In the United States, the vast majority of green roofs are found in commercial buildings and public spaces like community centres. According to DC Greenworks, a Washington D.C. nonprofit organization, there has recently been a shift in green roof installations from mainly commercial buildings to a mix of commercial and residential.
In Canada, the focus is more on residential-use green roofs. Dozens of developers in British Columbia have plans for green roofs on their condo buildings, and the Olympic Villages are at the forefront of these. Once the Games conclude, the Villages will become models for sustainable community living with housing, parkland, office and shopping complexes. However, because these technologies are still new and largely untested, B.C.’s insurance industry and homeowner protection office is reluctant to embrace the burgeoning green-roof industry.
The concern has been water damage due to faulty membranes on rooftops – an expensive mistake for any developer or insurer. However, millions of square feet of green roofs have been installed in countries like Germany with no signs of problems beyond those common for any roofing structure. In some cases, European insurance companies give buildings with green roofs better rates because of the reduced fire risk.
While many building owners and architects and even members of the public have shown interest in retrofitting their existing buildings with green roofs, there are many factors involved that need to be considered first. Robert Boltman, O.A.L.A. Associate Landscape Architect, advises that home owners and condo boards first learn how much weight the existing or proposed roof can handle or be designed or renovated to handle by means of weight load. After that “design is key from a structural purpose,” Boltman says, “and by working with landscape architects, a condo board can offer a lot more to potential home buyers. Amenity space is hard to come by in these days of fast urban sprawl.”
The benefits of a green roof are incredible. Not only is the environment protected, but communities in rooftop gardens are created, while everyone saves money with reduced energy usage.

Environmental Benefits
+Improved Air Quality: 1 m2 (10.76 ft2) of grass roof can remove between 0.2 kg of airborne particulates from the air every year.
+Carbon Dioxide/Oxygen Exchange: 1.5 m2 (16.15 ft2) of uncut grass, produces enough oxygen per year to supply one human with their yearly oxygen intake requirement.
+More effective building insulation.

Social Benefits
+Aesthetics: Urban greening has long been promoted as an easy and effective strategy for beautifying the built environment and increasing investment opportunity.
+Health & Horticultural Therapy: studies have shown that the restorative effect of a natural view as well as the additional oxygen, air filtration and humidity control supplied by plants holds the viewers’ attention, diverts their awareness away from themselves thereby improving health.
+Urban greening has long been promoted as an easy and effective strategy for beautifying the built environment and increasing investment opportunity.
+Improved Safety: A rooftop garden on the roof is often considered safer because access to the roof is usually restricted to building tenants or employees.
+Green roofs can help to address the lack of green space in many urban areas. Those who gave up their gardens for condo-living can now return to their green spaces.
+Local Food Production: Green roofs can provide new opportunities for urban agriculture.

Economic Benefits
+Protection of the roof membrane will result in a longer material lifespan (green roofs can potentially last up to twice as long as conventional roofs), resulting in decreased maintenance and savings in replacement costs.
+Savings on energy heating and cooling costs, depending on the size of the building, climate and type of green roof.