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Green Roofs
History
The history of green roofs date back thousands of years. The most famous green roofs were the Hanging Gardens of Babylon, considered one of the Seven Wonders of the World. These terraced structures, constructed around 500 B.C. were built over arched stone beams and waterproofed with layers of reeds and thick tar. Soil, plants and trees were then planted.
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Roofgreening.ca
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The most recognizable green roofs in North America were installed in the 1930's on Rockefeller Center in New York City.
In Renaissance Italy, garden terraces were popular form of green roof, later spreading across Europe. In Germany, vegetated roofs emerged in late 19th century as pioneering plants established on roofs that had tar and gravel applied in order to reduce fire risk.
German use of green roofs for stormwater management began in the late 1960’s . Significant research began in the 1970’s on storm water retention, growing mediums, plant types, drainage boards and root repellents. By 2001, annual construction of vegetated roofs equated to 13.5 million m2 and total green roof area accounted for 14 % of total roof coverage.
Green roofs emerged on the North American prairies with sod roof homes in mid 19th century. Recently, green roofs have re-emerged in North America for both their aesthetic and technical benefits. A number of vegetated roof research centers have been established since 2003 at Michigan State University (MSU), British Colombia Institute of Technology (BCIT), Pennsylvania State University and Institute for Research Construction Center in Ottawa. - Roof Greening.ca
Until the mid-20th century, green roofs were
viewed mainly as a vernacular building practice.
However in the 1960’s, rising concerns about
the degraded quality of the urban environment
and the rapid decline of green space in urban
areas, renewed interest in green roofs as a
"green solution" was sparked in Northern
Europe. New technical research was carried
out, ranging from studies on root-repelling
agents, membranes, drainage, lightweight
growing media, to plant suitability.
Green Roofing Canada-US
Canada and the United States are at least ten years behind Europe in investing in green roof infrastructure as a viable option for solving many quality of life challenges facing our cities.
In Canada, landscape architect Cornelia Hahn Oberlander, architects Doug Pollard and Charles Simon, and engineers Greg Allen and Mario Kani, are some of the people who have helped to establish the first green roofs. These include the Boyne River Education Centre in Southern Ontario and Robson Square in Vancouver. More recently, a volunteer group called the Rooftop Gardens Resource Group and an industry group called Green Roofs
for Healthy Cities have been working to develop the green roof market in North America.
A partnership of the National Research Council’s Institute for Research in Construction (IRC), Environment Canada , the City of Toronto, and Green Roofs for Healthy Cities has spearheaded research projects in Toronto, including the publicly-accessible roof of the City Hall.
At Laval University in Quebec, the roofing company Soprema is studying plant survivability in support of its Sopranature green roof product. A flurry of green roof-related research and demonstration activity is underway in Chicago, Portland, Winnipeg, and Ottawa.
At IRC’s Ottawa facilities a roof has been retrofitted to determine more detailed technical data on the performance of green roofs in areas such as energy efficiency and membrane life extension among others.- Steven Peck and Monica Kuhn
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Green Roofs Types
There are three basic types of roof garden and these three types relate to the amount of maintenance they require, the depth of soil and the types of plants the area will support. The three types are:
Extensive living roofs - Easy to maintain and use shallow soils. Extensive roofs are lightweight so tend to be used on sheds, garages and small extensions. They tend to be quite harsh environments so plants suitable are often ones found on cliffs and other harsh environments. However, whilst these roofs are easy to maintain they can also lack visual appeal.
Semi-Extensive living roofs - These roofs have deeper soils and can therefore support a greater number and wider variety of plants, making them more decorative. However their depth makes them heavy so they require a strong structure to support them. They can combine the relatively low maintenance of Extensive roofs with a more aesthetic appearance.
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IGRA
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Intensive living roofs - Intensive roofs are big old things capable of supporting full gardens and trees. As such they require large and strong support structures and are not suitable for the majority of domestic buildings. The Environmental Site
Advantages
Green roofs have four basic advantages:
They reduce the heat island effect that the building throws off into its local environment.
They help in storm water management – the water that hits the roof, stays on the roof.
They reduce energy costs because the building is not heating up in the summer very often, which reduces need for air-conditioning.
They create a new environment on sites where there was no green space, which helps to reduce smog and the replacement of green space that previously occupied a building footprint.
While there is an initial cost to put up a green roof, there is a definite energy savings. Daily Commercial News>
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The Rise of Urban Agriculture
Urban agriculture is the practice of cultivating, processing and distributing food in, or around, a village, town or city.
Urban agriculture contributes to food security and food safety in two ways: first, it increases the amount of food available to people living in cities, and, second, it allows fresh vegetables and fruits and meat products to be made available to urban consumers. A common and efficient form of urban agriculture is the biointensive method. Because urban agriculture promotes energy-saving local food production, urban and peri-urban agriculture are generally seen as sustainable practices.Wikipedia Although still relatively new in Canada, urban agricluture and rooftop food gardens are becoming more and more popular. Here is a sample of diffrent Rooftop Food Gardens in Canada:
From Rooftop to Restaurant - A University Cafe Fed by a Rooftop Garden City Farmer
Grow Veggies and Herbs From Your Condo City Farmer
Urban Agriculture Reaches New Heights Through Rooftop Gardening IDRC
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