Outlook - Living Roofs in Integrated Urban Water Systems - page 163

understanding of the mechanics, physics, biology and chemistry of living roof
systems.
Each of these components faces a number of challenges. Designers are agents
of their clients and therefore should adhere to their wishes and budgetary restric-
tions. Designers are also at the mercy of opportunities and limitations from build-
ing codes and by-laws, as well as their own motivation to express design ideas
and challenge conventional paradigms.
Accessibility is challenging in terms of life-safety responsibility and ownership
rights. In a private building, physical access to its living roof can be provided to its
residents at their own risk. Institutional and public buildings with living roofs may
offer a more universal accessibility, but as with all public space, liability associated
with rights of access are a grey area, especially as they concern, for example,
clients versus non-clients or staff versus non-staff, visibly homeless people, and
other demographic categories.
Municipal departments have the oversight of future building development,
including the provision and enforcement of living roof policies, strategies for
amenity and social space establishment, and technical requirements for manag-
ing stormwater. However, municipal by-law regulation and policy change are
generally slow processes, whose implementation is further challenged by a need
to update relevant design and construction guidelines. As only a small insight
into policy challenges, building height by-laws may require revision to prevent
new buildings from obstructing prime views from living roofs on existing build-
ings. A case in point, the City of Vancouver View Protection Guidelines explains
how different topographies and distances affect the impact of building heights
within view cones (City of Vancouver 2011). In the future, living roofs may be
considered as part of the landscape, acting as focal points for view cones. In the
meantime, living roof facilitation in general comprises a complex and continu-
ously evolving topic.
While policy can facilitate living roof implementation, policy can in turn be
supported by building owners and public investments in GI. Considering the
potential for long-term cost savings to fundamental public and private infrastruc-
ture, we believe that living roofs implemented as a component of a holistic urban
water system is a responsible and viable alternative to expensive, protracted and
often disruptive large-scale municipal infrastructure upgrades.
This topic offers a starting point for quantifying the potential stormwater miti-
gation effects induced by living roofs, based on extensive research and practical
experience. In the context of typical Western urban stormwater management
objectives and regulations, we summarize the state of the practice, identify limi-
tations and suggest future research needs. Living roofs alone cannot manage all
stormwater runoff, but when appropriately designed, constructed and main-
tained, they create a unique opportunity in the complex stormwater mitigation
system toolbox. Multiyear research campaigns are needed in all climates to quan-
tify the inluences on and evolution of the system's performance. These outcomes
must be translated into practical design advice and relevant policy.