Case studies - Living Roofs in Integrated Urban Water Systems - page 145

3 LIVING RooF ASSEmBLy
The roof's undulating planes simulate rolls and hummocks with gentle slopes of 5
percent to near vertical grades. Due to these various roof proiles, different systems
were used to make the planting of the roof possible. These systems include engi-
neered pockets for growing media retention and erosion control; waterproofed
shear barriers built into the steep areas of the structure to keep the system from
slipping; and interlocking, honeycomb-shaped modules to hold the growing media
in place on areas of extreme slopes. The system throughout also consists of a
mechanical root barrier; anti-shear geotextile protection mat growing media reten-
tion modules; a custom growing media mix developed in collaboration with a spe-
cialist living roof company and the local supplier; and a two-ply SBS membrane, in
addition to a leak detection system, root barrier cap sheet and drainage mat.
4 RAINWATER CoLLECTIoN
The roof is the cornerstone of the project's water conservation strategy with six
individual undulating roof petals: two blue roofs for water collection and solar
hot water tubes, and four planted petal-shaped living roofs. Runoff from the
living roof is directed to the existing stream, enhanced iniltration beds and wet-
lands in addition to an underground cistern. The rainwater collection cistern is a
134,000 liter tank beneath the building. The greywater is iltered and used in
toilets and urinals.
Despite City requirements for both water and sewer systems to be connected
to the city service, the Visitor Centre is one of the irst buildings in Vancouver in
more than 45 years to treat blackwater on-site (using a bioreactor wastewater
system). Blackwater from toilets and urinals is reclaimed and sent to the bioreac-
tor for treatment, directed to a percolation ield, and then returned to the sur-
rounding garden wetlands. Through this comprehensive process, the project
shines as a truly net-zero example of an off-grid water system.
5.2.2 Single lot: Port of Portland Headquarters, Portland, Oregon, USA
5.2.1.1 Project overview/objectives
Located between two active airplane runways, the Port of Portland Headquarters
is a ten-storey structure that serves as a long-term Port of Portland Headquarters
ofices and parking garage (see Table 5.2 and Figure 5.2 ). Incipient primary
design objectives included adherence to Portland's pursuit of sustainable develop-
ment practices. To accomplish this goal, the Port sought a highly functional build-
ing with a minimum LEED- NC (LEED - New Construction) Gold rating, while
targeting LEED- NC Platinum rating, which was achieved in 2011. Achieving this
standard of LEED certiication mean incorporating many eco-friendly systems,
including the effective use of daylighting and daylight harvesting, exterior glazing
and sun- shades, geothermal heating and cooling, near Net- Zero (90 percent)
waste diversion, low-low water ixtures, a highly visible and prominently fea-
tured living machine, and two living roofs, all of which would help the facility
save energy and reduce operating expenses. As such, the building has been the