The Centre was established in 2003 with the construction of a dedicated research facility at the Great Northern Way campus. As part of its polytechnic stream, the Centre's mandate is applied research and education. The Centre also works with industry for direction on education and policy mechanisms, and conducts third party testing of industry products to help optimize system designs according to the local climate.
The first phase of research (2002-2007) produced results describing the effects of stormwater mitigation and thermal efficiency by extensive green roofs in the climate of coastal B.C. In addition to the Green Roof Research Facility, a regional infrastructure network evaluates performance green roof performance in other parts of the province. The next phase of research (2007 - 2010) will broaden to include native plants on the Elevated Research Platform, living walls, and sound transmission characterization of green roofs.
The Centre for Architectural Ecology supports the academic, design, and construction communities to understand and advance green roof and living wall technologies in this region. BCIT students (building science, architecture, environmental science, engineering technology and trades programs), as well as students from regional universities and other institutes, are involved in various research projects based on their area of study. The green roof courses are popular for practicing professionals, too, and qualify for learning units by the Architectural Institute of B.C., the B.C. Society of Landscape Architects, and the Planning Institute of B.C.
Mailing Address
Centre for Architectural Ecology - Collaborations in Green Roofs and Living Walls
NE3 - 3700 Willingdon Ave.,
Burnaby, BC V5G 3H2
Green roofs are engineered roofing systems incorporating the use of vegetation that make environmental, economic, and social contributions to urban areas. The Green Roof Research Facility focuses on extensive green roofs.
Green roofs have limited impact in short span construction. The weight of a 3" green roof is approximately equal to gravel ballast use in inverted roof systems. For long span construction, load considerations may require structural engineering.
There are three types of green roofs:
1. Extensive Green Roofs - designed for environmental solutions
- 3- 6" of light weight growing medium.
- low-maintenance ground-cover plants.
- ideal for large flat-roof buildings and apartments.
- suitable for low-sloped residential roofs and retrofits.
- desert grasses and succulent plants.
- after one year, they do not require watering.
- annual spring weeding of tree seedlings & weeds - brought in by birds and wind.
2. Intensive Green Roofs - also known as rooftop gardens
- 8-12 inches, or more, of growing medium.
- fully landscaped roof top garden.
- require regular maintenance -similar to an at-grade garden.
- diverse plants and trees can be planted (avoid plants with invasive root systems).
- walkways, railings and lighting.
- parks, playgrounds or vegetable gardens are possible.
3. Semi-intensive Green Roofs - elements of both extensive and intensive systems
Semi-intensive roofs, combinations of both extensive and intensive green roofs, are typically adopted to harness both the environmental benefits of a green roof, as well as a diverse garden within a manageable maintenance budget.
Planting the rooftops of urbanized areas brings many benefits to public, private, economic and social sectors, as well as to the local and global environments. While all green roofs have similar functions, each installation is unique, so technical performance will vary by region, climate, building and green roof type and design. The benefits described below can be achieved by virtually all green roof systems and designs.
Benefit: Green roofs reduce stormwater runoff
During heavy or continuous rain, runoff can overwhelm stormwater infrastructure and potentially damage waterways and fish habitat.
Benefit: Green roofs are energy efficient
Green roofs reduce the heat flux through the roof, and less energy for cooling or heating can lead to significant cost savings. Shading the outer surface of the building envelope has been shown to be more effective than internal insulation.
Benefit: Green roofs improve air quality
Plant leaves trap dust particles from the air, and evapotranspiration cools ambient temperatures.
Benefit: Green roofs can serve as habitat
As undisturbed areas, rooftops can serve as refuge for creatures that struggle for survival. Ground-nesting birds, such as Killdeer, use green roofs for nesting and raising their young.
Benefit: Green roofs last longer
Green roofs cover the waterproofing membrane, protecting it from UV rays and extreme daily temperature fluctuations. This protection extends the lifespan of the waterproofing twice as long as conventional roofing, meaning that membranes under green roofs last twice as long as those on traditional roofs.
Benefit: Life cycle costs are competitive
The initial installation cost of a green roof is more than a traditional roof; however, the life cycle cost is competitive. Try out Green Roofs for Healthy Cities' Green Save Calculator.
Benefit: Green roofs provide 'extra' space
Green roofs make the most of unused space within the increasing density of our cities. Rooftops can be developed into social and recreational spaces and used for urban agriculture.
Benefit: Job creation
A new industry represents a new market that will provide employment opportunities:
Other Benefits
Green roofs offer so many benefits, it's hard to imagine listing them all. Here are a few more:
Extensive green roofs are lightweight adaptations of sod roofs, like those found in Scandinavia during the Viking and Middle Ages. In fact, reconstructions of Norse sod houses dating from 1000 A.D. are protected as a UNESCO World Heritage Site in L'Anse aux Meadows, Newfoundland, and commemorate the earliest known European settlement in North America. Green roofs are an old idea!
During the oil crisis of the 1970s, West Germany explored lightweight adaptations of sod roofs for the purpose of energy conservation. Since that time, extensive green roofs have been lauded for their many benefits as cost-effective solutions for urban environmental problems. By 2005, an estimated 13 million m2 roof area in Germany was covered with plants.
As cities in other parts of the world learn about the benefits of extensive green roofs, adoption of this lightweight technology has been growing worldwide. In North America, the industry association Green Roofs for Healthy Cities was founded in 1999, and has organized annual green roof conferences every year since 2003. Cities that have adopted programs and/ or policies which promote extensive green roofs include Chicago, New York, Toronto, Portland, and Washington D.C.
Extensive green roofs were originally developed, tested and evaluated in the temperate climate of western Europe, which is typified by warm summers with frequent rains and cold winters. Eastern North America shares a relatively similar climate, if somewhat more extreme. The climate of the Pacific North-West, however, is dramatically different from both of these regions. Here, our summers are hot and dry, and our winters mild and wet.
In Vancouver and within the greater Georgia Basin and Puget Sound bioregion (ranging from Whistler in the north to Puget Sound in the south), population growth is yielding problematic runoff issues and unsustainable rates of energy consumption. In 1960 the region was home to 2.6 million people living and working in an area connected by sea, rivers, forest and mountains. By 1996, the population had risen to over 6 million, and by 2020 there may be an additional 3 to 5 million people. Fortunately, people are beginning to recognize that green roof technology can help address the problems associated with impervious urban growth. (Source: GVRD Livable Region Strategic Plan (1999))
Green roofs and photovoltaic panels are complementary technologies that improve each other's performance. The PV functions more efficiently thanks to the cooler ambient temperatures above the green roof, and the green roof benefits from the areas of shade. Read more about the synergistic relationship between green roofs and solar panels here:
Appl, R. and W. Ansel. 2004. Future oriented and sustainable green roofs in Germany. In: Proceedings from the 2nd annual Greening Rooftops for Sustainable Communities conference, awards and trade show. Portland. OR. Green Roofs for Healthy Cities.
Koehler, M. et al. 2002. Photovoltaic panels on greened roofs: Positive interaction between two elements of sustainable architecture. In: Proceedings from Rio 02-World Climate & Energy Event.
The first step in considering a green roof for an existing building is to have its structural loading capacity assessed by a structural engineer. With this figure, which must include both live and dead loads, you can then decide what kind of green roof system the roof will support.
Depending on the system used, extensive green roofs weigh between 60 and 240 kg/ m2 (Kolb & Schwarz, 1999). If you wish to retrofit a ballast roof, the weight of the ballast may match the loading required for an extensive green roof. The structural engineer will provide you with this important information. For details about regionally-available green roof systems, components, and/ or services, visit our industry products page.
Reference:
Kolb, W. and T. Schwarz. 1999. Dachbegrünung: Intensiv und extensive. Eugen Ulmer, Stuttgart.
