Case studies - Living Roofs in Integrated Urban Water Systems - page 144

5.2.1.3 Resource use and management
Water : net zero via rainwater catchment and on-site blackwater treatment. An
Integrated Stormwater Management Plan (ISMP) was developed to meet both
the LBC and LEED Platinum. The requirements, respectively, meant that 100
percent of the site stormwater and building water discharge was designed to be
integrally managed on site, and where the following credits were to be achieved:
Credit 6.1: Stormwater Management (Rate and Quantity) and Credit 6.2: Storm-
water Management (Treatment).
Energy : net zero via solar hot water, photovoltaic panels, geothermal bore-
holes. The project's natural ventilation was made possible by a solar chimney in
the roof, which converts sun's rays to convection energy.
5.2.1.4 Key living roof design features
1 PROCESS
Adhering to the Rooing Contractors Association of British Columbia (RCABC)
warranty was an example of a practical construction policy for the project's com-
prehensive design process. As per the requirements of the RCABC, the project's
living roof, rooing membrane and roof installation were submitted as one com-
plete tender. Together with the supplier, both the envelope consultant and struc-
tural engineer extensively reviewed and approved the shear barrier design,
locations and installation.
Due to its lightweight media speciication with 150 mm, on average, and
unique curvilinear shape, special coordination was required between the suppli-
ers and the landscape architecture and architecture teams. The roof is designed
to support about 220 kg/m 2 . A custom grid shell of sustainably harvested (FSC) ir
individually-shaped, glulam members support the roof, and shear barriers are
integrated within the roof deck and membrane systems to prevent the living roof
system from slipping off the roof.
2 LIVING RooF PLANT SELECTIoN AND SITE CoNNECTIVITy
Shaped like the petals of an orchid, the roof relects the Paciic Northwest Coastal
grassland community and includes over 20 species (approximately 14,000 in
quantity) of in-situ plants, native perennial bulbs, together with custom fescue
hydro-seed grass mix. The site grading brings the existing botanical garden onto
the roof to create key sightlines between the main arrival bridge, upper terrace,
restaurant and street, and throughout the gardens - reinforcing the seamless
building/site relationship. The continuous green space also creates a wildlife cor-
ridor. The low-growing fescue requires minimal mowing and fertilization, and is
dormant in the winter. The roof has no artiicial irrigation system (nor does the
at-grade garden landscape). Therefore, the survival of the roof vegetation relies
on plant selection optimally suited to the local climate and a specialized mainte-
nance program that has been developed with the Botanical Garden Horticulture
Maintenance team.