Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
South Australian Government Incentive Program:
Bushtops for Green Roofs and Walls
The South Australian Government, through its planning arm Planning SA, is leading the
development of an innovative green roof and living wall incentive program to bring the
Australian “bush” into the city of Adelaide – “Adelaide’s innovative green wall and roof
incentive policy set to be a model for other Australian cities” heads up an article in the
Winter 2008 issue of the North American Living Architecture Monitor.
This incentive program encourages Government agencies to implement green roofs and
walls, but also demonstrates the complexity and interdependency of the interaction
between ecosystems. There are four components that make up this program: what are
bushtop roofs and walls, creating stepping stone corridors, integration into green
infrastructure, and increased residential density.
First of all, we need an understanding or an explanation of what these components are
and how they integrate with each other to create a sustainable environment.
Bushtops
Bushtops are a series of living walls and green rooftops, that mimic the endemic
ecosystems of the original landscape of the city, in this particular case the City of
Adelaide. Bushtops are not just the physical structure of habitats or ecosystems, they
introduce the relevent animal species into this type of green roof and living wall from the
early design and implementation stages. Particular emphasis is placed on providing
habitat for species that were once common in the Adelaide Plains, by planting selected
native grasses, sedges and flowering plants. Bird boxes will be installed into the various
ecosystems, as well as bat boxes that attract micro-bats, useful in the control of
mosquitoes and flying ants.
Bushtop ecosystems allow natural systems to operate processes such as: stormwater
retention, improving water quality, evaporative cooling from plants, bio-filtration of airbourne pollutants, and increased carbon dioxide/oxygen exchange through
photosysnthesis or carbon sinks. A good example of this process is creating a
constructed wetland ecosystem as a bushtop roof or wall to treat the grey water from the
building and then returning the water back to the building as recycled water or even as
potable drinking water.
Stepping Stone Corridors
The plan is to linked individual projects together, based on patch dynamics and
metapopulation theories, to form stepping stone wildlife corridors across the central
business district to restore the original migration patterns of birds, insects and certain
animals.
Green walls will connect the bushtops to the ground and allow the passage of animals
and insects between the vertical and horizontal planes. The projects will be carefully
integrated with current research at the School of Urban Ecology at the University of
South Australia and it is expected that Planning SA’s program will be a major platform
for the reintroduction of species back into Adelaide’s urban environment.
Green Infrastructure
Green infrastructure is a process of designing natural systems into the urban
environment, or using natural systems to replace or augment existing services that
support the built infrastructure systems. The city is an urban ecosystem, with natural
systems being smaller ecosystems within the overall urban ecosystem. These systems
utilise the complex interactions of the earth’s natural cycles (hydrologic, nitrogen,
Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
oxygen, carbon and others). These elements in the natural systems provide processes
that repair, transform and transport matter, clean water and break down pollutants.
These processes are vital for a healthy sustainable urban ecosystem.
Green roofs and walls become part of a multi-layered corridor by bio-mimicking natural
sytsems to create green infrastructure throughout the city. This green infrastructure
adapts to the changing conditions caused by climate change. Green roofs and walls are
one of many tools to be used in the urban environment affected by climate change. For
instance they have an important role to play in stormwater management at the source,
reducing the heat island effect, and providing carbon sinks.
The green roofs and living walls mimic natural systems in many ways, but are
particularly important for the removal of pollutants through capturing pollutant particles
on plant leaves and deposits on the roots, where micro-organisms feed to convert this
into water, carbon dioxide and nutrients. This process provides water and water vapour
as an end product. The green roofs and living walls have all the same natural systems
as the ground level environment, but are set up artificially.
The stormwater chain in a natural system is the capture and retention of stormwater at
its source, and its reuse or infiltration. In green infrastructure this natural process is
mimicked by using green roofs and living walls to capture and retain the rainwater that
falls on them, thus eliminating a large volume of stormwater at its source.
Increased Residential Density
The SA government has a policy of increasing the population, especially in the inner
metro areas through infill programs. This increased density development is usually to
the detriment of open space or the landscape bio-mass. The increased built form can
be offset by using green roofs and walls integrated into the design of the built form. By
employing living wall methodolgy, the backyard or courtyard can be tilted up vertically,
creating both extra space for another building and also retaining the same amount of
landscape or bio mass.
Green roofs and walls to preserve biomass
Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
This concept can be taken further by adding another dwelling to the site and
incorporating a green roof and living wall to increase the landscape/biomass along with
the built form density. Developing this process even more, it is possible to increase the
built form density and create more landscape/biomass than the site had in the predevelopment stage.
The advantages of this building technology are an increase of biomass and biodiversity,
together with the expected environmental benefits to the building interior, and an
increased capacity in stormwater retention and detention of the site via the bushtop
roofs and walls. The downside is a loss of deep root zone for large trees and ground
infiltration of stormwater. Some of the landscape/biomass areas may not be usable for
active open space as it is vertical or an extensive (and therefore non-accessible) roof
system, the need for recreational open space will have to be accommodated elsewhere
in the development or as part of an integrated public open space system.
Program
South Australian Government buildings or projects and projects financed by the State
Government can access design services for concept design and development for
bushtop green roofs and walls. This will be a free professional design service for these
projects.
Planning SA’s program includes unique green roof and living wall incentives for
Government buildings and projects. Often with many Government agencies, monies for
incentive programs are limited and very competitive, so a pioneering idea may have very
little leverage to attract funding. However, under this new incentive program,
Government projects can now access design and development services via Planning
SA’s Principal Urban Designer's expertise in green roof and living wall design. This is a
free service for government projects to encourage the inclusion of green roofs and walls
into their sustainable projects; an effective way to incorporate this green technology into
new buildings or revitalisation projects.
This concept design and development service may range from informed advice at the
conceptual stage of a project through to the full conceptual design and development
documentation of a green roof or living wall system prior to construction documentation.
The construction documentation will be carried out by the Government agency or their
consultant. Technical advice may be provided during the construction documentation
stage and the implementation of the bushtops.
The unique nature of this incentive program is that Government agencies/client groups
have no additional costs for concepts and designs, and that Planning SA has no extra
costs, this depends on that Planning SA has the technical knowledge to provide this
service.
The Government can lead by example by developing demonstration projects without a
design cost penalty. A major spin off from the demonstration projects is the influence
that this will have on the private sector in the competitive sustainable green building
market. As Government projects push the boundaries in the sustainable world and
demand higher green ratings for their leased spaces then the commercial sector with
respond with green building advancements.
Current Projects
A stepping stone corridor is being planned to build on from the successful Hocking Place
Bushtop project on a State Government housing development and the neighbouring
private development of the Christies Walk rooftop. By linking a series of green roofs
Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
across the city to connect with the surrounding parklands, habitat opportunities will be
provided for a range of species.
Planning SA is investigating the technology of bushtop roofs and walls to maintain or
increase open space and landscape/biomass in the increased residential infill density
program. This techology will become one of the many techniques used to increase
density and livability in the inner metro. The bushtop roof and wall program will become
the most visible and environmentally important of all the techniques employed.
The bushtop for green roofs and walls program has already been implemented in
several other Government city-wide projects that are in the conceptual development
stage, including the new State Government Margery Jackson-Nelson Hospital featuring
green roofs and walls integrated into various levels, as part of the sustainable design
content required by Government.
A high profile project that has State and Federal Government funding and incorporating
the bushtop program, is the New Entry and Administration complex to Adelaide Zoo that
features a long living wall leading into the Entry and transitioning from a living wall into a
series of green roofs. This complex is being designed by Hassell.
Adelaide Zoo new development designed by Hassell
Flow-on Effect in Government and Local Government
There is a natural flow-on effect from this incentive program to other levels of
Government, such as Local Government. Like all organisations Local Government
wants to be seen at the cutting edge and providing the best outcome for their rate
payers. So as Government encourages the bushtop program, Local Government takes
up the concept as well. An example is the development of a green infrastructure project
for University of South Australia and partnered by Adelaide City Council, which was
developed and brokered by Planning SA using this incentive program. This project
would not have developed without the incentive program, which has provided expertise
Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
and time developing this multi-layered green infrastructure, with living walls and green
roofs forming a vital component of this urban ecosystem.
Adelaide City Council has already produced a Fact Sheet on Green Roofs for Medium
Density Housing and, combined with the bushtop program, these devices can be
targeted to Government housing in the Adelaide City Council area to encourage the
further development of green technology.
Adelaide City Council fact sheet
Catalyst for Private Sector
These Government incentives are creating a catalyst for private development of green
roofs and walls. By Government providing incentives it demonstrates that it is taking
seriously the benefits of this technology for urban development, and this will gradually
infiltrate into mainstream design of sustainable green buildings. Also this gives these
projects a competitive advantage in their position in the sustainable green building
market, including benefits to the Government leasing policy.
Developers are starting to see advantages of these green technologies and are
incorportating them into their buildings, as evidenced by the College Street Apartments
at the Adelaide beachside suburb of Glenelg, designed by Woods Bagot for Urban
Construct.
Graeme Hopkins Hopkins.Graeme@saugov.sa.gov.au
May 2008
South Australian Government Incentive Program: Bushtops for Green Roofs and Walls
New development at Glenelg designed by Woods Bagot
Conclusion
It is important that Government takes on a leadership role in these new technologies in
the sustainable green building industry. This leadership, especially by example, sends a
powerful message to the community and industry that Government is serious about
sustainability and climate change. This program is innovative in the way it uses avaliable
resources within Government, and especially by not requiring extra capital expenditure.