Materials - Rooftop Gardens/Planted Roofs
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Global Summary Building Summary Design Options Materials Stone Glass and Plaster Metals Earth Wood Strawbale Planted Roofs Ventilation Energy Savings Building Config. Room Layout Solar Orientaion Cooling/Heating Water Heaters Water Conservation Landscaping Rainwater Waste Water Readings Examples
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A roof garden alone does not denote environmental architecture, but it
addresses such issues as energy savings from improved insulation, air quality,
and aesthetic beauty. Roof gardens can be found in the architectural history
of the American Pueblos, and Tibetan mountain villages. LeCorbusier
stated in 1923 that ‘the roof garden is becoming the favourite place to
be in the house and means furthermore for the city, winning back of the
whole of its developed area.” There is also the potential for urban
agriculture providing us with fresh fruit and vegetables.
Université Laval’s Horticultural Research Centre started a roof garden project in 1994. It now provides research findings that have determined which plant species had good adaptability to the Canadian climate, as well as minimum thickness and type of growing medium for each species, in order to minimise winter damage. Their research further illustrates that roof gardens improve urban air quality by regulating carbon dioxide and producing more oxygen. Urban heat islands can be reduced by the capacity of large areas of vegetation to absorb the sun’s rays. In regions susceptible to flooding, green roofs are used to control storm runoff through their capacity to retain between 70% and 100% of precipitation. Roof gardens also create an increased biodiversity of plants, animals, and insects. There are also energy savings from reduced heating costs (raising of winter roof temperatures by up to 15c) and reduced cooling costs (lowering summer roof temperatures up to 40c). The life of the roof is also extended. In Québec, there are two companies that offer roof garden expertise for not only flat roofs, but also roofs with slopes up to 40% (Soprema of Québec City and Hydrotech of Montréal) Both of these companies produce the necessary membrane that protects the roof structure from organic and water penetration. 
Section through a planted roof, indicating the measures needed to retain moisture to allow the plants to grow, to provide insulation, and prevent moisture entering the building. |
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