Green Roofs for A Wide Brown Land - the University of Melbourne

Green roofs for a wide brown land?-Research required to develop a successful Australian industry

Nicholas S.G. Williams, John P Rayner and Kirsten J Raynor

Department of Resource Management and GeographyGraduate School of Land and Environment

The University of Melbourne

Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

Green Roofs are SexyIn recent months there have been media stories in:• The Age• Sydney Morning Herald• Daily Telegraph• Horticulture Australia• Gardening Australia• Radio 2SER• Radio National: By Design• Moreland Leader• Queensland Property and Lifestyle magazine • Business Week

Highrise horticulture ... the rooftop garden at M Central in Pyrmont.Photo: Lee Besford SMH


Most Australian examples are intensive green roofs

Private home Sydney. Photo: Gardening Australia

Converted car park, Sydney. Photo: Gardening Australia

30 cm + substrate depth


Marine Discovery Centre, Queenscliff,

Most Australian examples are intensive green roofs

Crown CasinoMelbourne


• relatively nutrient rich, deep substrate (> 30 cm)

• allows for establishment of greater range of plants: trees, shrubs and conventional lawns.

• require high level of maintenance, regular irrigation and applications of fertiliser

• weight can be considerable requiring substantial reinforcement of an existing roof or extra building structural support

• Therefore $$$$ and difficult to retrofit

Intensive Green Roofs

Freshwater Place, Melbourne (Photo: Fytogreen)


• Shallow, low-nutrient light substrates 2-15 cm deep

• low maintenance, usually no irrigation or fertilisation (may be required initially)

• Potentially provide greater biodiversity benefits than intensive roofs, - ‘Ecoroofs’

• planted with, or colonised by, mosses, succulents, some wild flowers and grasses

• Few (None?) in Australia

Very Few Extensive Green Roofs

Semi-extensive green roof on CH2 building, Melbourne

Substrate 20-29 cm deep


Extensive vs Intensive

In North America, most of industry growth is for extensive or semi intensive green roofs

• Overall 30 % industry growth in 2007 • Number of extensive green roofs

increased by 40% in 2007• Number of intensive green roofs

decreased by 247% in 2007

Green Roof Industry Survey 2007


Why are there no extensive green roofs in Australia?


• A major barrier is the lack scientific data available to evaluate their applicability to Australian conditions.




• Relying on northern hemisphere experience and technology is problematic due to significant differences in rainfall, temperature, available substrates and vegetation.





• This may introduce unacceptable levels of risk and unnecessary expense to projects





• This may introduce unacceptable levels of risk and unnecessary expense to projects

• Basic research is needed to objectively evaluate the performance, cost and environmental benefits of green roofs in Australia


Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008 http://www.greenroofmaps.com/

Indicative World distribution of Green roofs


http://ag.arizona.edu/~lmilich/pe.html

The Australian Climate is different


International Green Roof Research

• Europe: 30-40 years• Nth America: 15-20 years• United Kingdom: 10-12 years• New Zealand: 3-4 yearsMany universities have independent green roof

research and testing facilities– University of Sheffield http://www.thegreenroofcentre.co.uk/index.html

– Michigan State http://www.hrt.msu.edu/greenroof/

– BCIT http://commons.bcit.ca/greenroof/

– North Carolina State http://www.bae.ncsu.edu/greenroofs/– Penn State http://hortweb.cas.psu.edu/research/greenroofcenter/


• Europe: 30-40 years• Nth America: 15-20 years• United Kingdom: 10-12 years• New Zealand: 3-4 yearsMany universities have independent green roof

research and testing facilities– University of Sheffield http://www.thegreenroofcentre.co.uk/index.html

– Michigan State http://www.hrt.msu.edu/greenroof/

– BCIT http://commons.bcit.ca/greenroof/

– North Carolina State http://www.bae.ncsu.edu/greenroofs/– Penn State http://hortweb.cas.psu.edu/research/greenroofcenter/

International Green Roof Research


University Research Facilities

• Replicated green roof modules or experimental plots

• Monitored for runoff quantity and quality, plant performance, energy use

• Funded by green roof component suppliers, government or companies wanting to build a green roof

• Establishing facilities at University of Melbourne, Burnley Campus

Penn State University

Oregon State University

University of Sheffield


Key Questions – Substrates

• Northern hemisphere substrates are well established but transport costs and materials differences necessitate that local substrates be developed.

• Unlike the green roof industry in North America and Europe, the few Australian proprietary products available have not been independently tested.

• May need to develop different mixes for different locations based on availability and cost


Key Questions – Substrates

• What substrates are available?• How do various substrate materials and

mixes perform under Australian roof conditions?– Temperatures can be as high as 90 C

• What depth of substrates are required for plants in the Australian climate?

• What are the lifecycle costs (sustainability) of substrate components


Key Questions - Plants• In temperate Northern hemisphere sedum

species are typically planted on extensive green roofs. – Collapse and die in extended periods of hot

weather– may not be suitable for Mediterranean or sub-

tropical climates in Australia’s major cities• Very little is known about the suitability of

Australian plants for green roofs. • Overseas interest in potential of drought

adapted Australian species.


Key Questions - Plants• Are there native plants that will survive on

extensive green roofs in Australian climates• Or do they require supplementary irrigation? • What is the minimum depth of substrate

required for survival?• What is the performance of Australian plants

relative to species used in the Northern Hemisphere?


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More likely to be a Brown Roof?

Brenneisen S. 2006. Space for Urban Wildlife: Designing Green Roofs as Habitats in Switzerland. Urban Habitats 4: 27-36.

Kangaroo and Wallaby grasses with everlastings


• What are the stormwater volume and peak flow reductions in Australian climate conditions?

• How does this vary with substrate depth and planting palette?

• How do various substrates affect water runoff quality– Some mixes / components may leach N

• Can we use grey water on green roofs?

Key Questions - Water


• What is the potential impact on building energy performance

• Can green roofs cool the urban landscape?– providing 50 % green roof cover in New York

would lead to an average 0.1-0.8°C reduction in surface temperatures.

– for every 1°C reduction 495 million kWh saved– Will only work if irrigated- can’t use potable H2O

• What are the full environmental costs and benefits of different types of green roofs over their lifecycle?

Key Questions – Energy and lifecycle


Green Roof Research @The University of Melbourne

• Established a 20m2 experimental extensive green roof at the Burnley Campus

Using it to:1. Select plants that will survive and look good

in Australian climatic conditions2. Develop a locally produced light weight

substrate3. Investigate the effect of the green roof on

building energy budgets


• Investigating the drought tolerance of selected succulents, grasses and herbs

• Evaluating the properties of substrate components and mixes

• Determining the effect of recycled water on green roof substrates


Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008 Source:Zinco Planning Guide, 6th edition

• Green Roof system donated by ZinCo

• Used the FloraDrain40 system

• 125 mm of substrate



125 mm

• Green Roof system was donated by ZinCo

• Used the FloraDrain40 system

• 125 mm of substrate 40 mm

Source:Zinco Planning Guide, 6th edition



Root resistant water proofing


Fitting eaves to frame


Rolling out protection layer


Adding drainage layer



• Adding substrate and initial planting mid July

• Need to finalise plant selection• 10 individuals of 32 species• 20 cm plant spacing• Upright succulents, herbs

spreading succulents and grasses in separate quadrants

• Irrigation to establish only



• Attractive• High tolerance to light• High ‘drought’ tolerance• Robust and moderate to high vigour• Easily maintained• Tolerate seasonal water logging?• Possum proof? • Available

Plant Selection Criteria


Habitat Templates

Gibber Chenopod ShrublandsImage: Rob Jung

Alpine rocky slopes

Native grasslands. Photo Georgia Garrard


Potential Plant Species

Lomandra multiflora subsp. dura

Wallaby Grasses(Austrodanthonia sp)

Rounded Noon Flower(Disphyma crassifolium)


Enchylaenatomentosa


Sedum mexicanumRhodanthe floribunda


Pigface (Carpobrotusrossii)

Blue Chalk Sticks(Kleinia mandraliscae)

Dianellarevoluta Phormium

‘Thumbelina’



Pigface (Carpobrotusrossii)

Blue Chalk Sticks(Kleinia mandraliscae)

Dianellarevoluta Phormium

‘Thumbelina’


XX

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Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008 Semi-intensive green roof @ CH2. Media 20-29 cm deep


CH2 East Core Roof – February 2008


Conclusions

• Extensive green roofs have great potential as a climate change adaptation strategy– Less expensive– More easily retrofitted

• Few extensive green roofs in Australia• Many candidate native plant species• Need research for Australian conditions


Conclusions

• Extensive green roofs have great potential as a climate change adaptation strategy– Less expensive– More easily retrofitted

• Few extensive green roofs in Australia• Many candidate native plant species• Need research for Australian conditions• Hopefully our work we can help fill this

information gap


Acknowledgements

• John and Kirsten• Funding provided by The University of

Melbourne-CSIRO Collaborative grant scheme

• Materials provided by ZinCO• Peter May• Ross Payne

Education

Green Roofs for A Wide Brown Land - the University of Melbourne