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Meadows in the sky : contemporary applications for eco-roofs in the Vancouver region

University of British Columbia

In Vancouver, British Columbia, Canada, issues once thought isolated to large metropolitan areas such as Los Angeles, Tokyo, and Mexico City—increased storm water runoff, the urban heat island effect, deterioration of air and water quality, and loss of habitat and biodiversity—now threaten a region once described as "lotus-land" (Wynn and Oke, 1992, xi). European research supports the ability of green roofs to mitigate many of these ill effects of urbanization. The investigation undertaken by this thesis explores the role green roofs might play in the Greater Vancouver's transition to sustainable design and development. The thesis limits the scope of its investigation to inaccessible, extensive systems, alternately known as eco-roofs, which are relatively lightweight and low-maintenance. The paper reviews the historical and contemporary development of eco-roofs, including past and present motivations for their use and the evolution of construction methods. It then summarizes the potential impacts—aesthetic improvements, increased biodiversity, protection of the roof membrane, meso and microclimate mitigation, improved building insulation, and stormwater management—currently attributed to green roof implementation. The remainder of the thesis evaluates which of these potential impacts apply to Vancouver, in light of the city's physical contextual setting, and the ambient influences of the Greater Regional District The reported benefits of green roofs are numerous, and incremental contributions to improving environmental conditions should not be discounted or trivialized, however, in Vancouver and its region, eco-roofs' greatest impact, and consequently financial feasibility, resides in the mitigation of stormwater volumes. Eco-roofs' detain rainfall and slow runoff from the roof during and immediately following a storm event. This reduces peak flows, and corresponding CSO and flooding problems, and encourages a more natural hydrology by increasing the chances for stormwater infiltration. Storm runoff, and issues related to it, constitutes a persistent and growing problem in the GVRD. The ability of an eco-roofs even thin profile to mitigate this pressing issue could result in widespread, and even unforeseen, positive ramifications.

Thesis/Dissertation

application/pdf

2009-07-29

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http://hdl.handle.net/2429/11448

Architecture

University of British Columbia

UBCV

DSpace