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

1. 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 Geography
Graduate School of Land and Environment
The University of Melbourne

2. Green Roofs are Sexy
In 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 Highrise horticulture ... the rooftop garden
at M Central in Pyrmont.
• Moreland Leader Photo: Lee Besford SMH
• Queensland Property and Lifestyle magazine
• Business Week
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

3. Most Australian examples are
intensive green roofs
Private home Sydney. Photo:
Gardening Australia
Converted car park, Sydney.
Photo: Gardening Australia
30 cm + substrate depth
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

4. Most Australian examples are
intensive green roofs
Marine Discovery Centre, Queenscliff,
Crown Casino
Melbourne
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

5. Intensive Green Roofs
• 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
Freshwater Place, Melbourne
• Therefore $$$$ and difficult to retrofit (Photo: Fytogreen)
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

6. Very Few Extensive Green Roofs
• 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, Semi-extensive green roof on
some wild flowers and CH2 building, Melbourne
grasses Substrate 20-29 cm deep
• Few (None?) in Australia
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

7. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

8. Why are there no extensive
green roofs in Australia?
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

9. 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.
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

10. 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.
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

11. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

12. 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
• 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

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

14. The Australian Climate is different
http://ag.arizona.edu/~lmilich/pe.html
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

15. International Green Roof Research
• Europe: 30-40 years
• Nth America: 15-20 years
• United Kingdom: 10-12 years
• New Zealand: 3-4 years
Many 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/
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

16. International Green Roof Research
• Europe: 30-40 years
• Nth America: 15-20 years
• United Kingdom: 10-12 years
• New Zealand: 3-4 years
Many 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/
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

17. 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 Oregon State University
a green roof
• Establishing facilities at University of
Melbourne, Burnley Campus
University of
Sheffield
Penn State
University
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

18. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

19. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

20. 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.
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

21. 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?
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

22. 35 rain
evaporation
30
reservoir
Available water (mm)
25 0.2E
20
15
10
5
0
0 20 40 60 80 100 120 140
Nov Dec Jan Feb
Days since Nov 1st 2007
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

23. 35
rain
30
evaporation
Available water (mm)
25 reservoir 0.4E
20
15
10
5
0
0 20 40 60 80 100 120 140
Nov Dec Jan Feb
Days since Nov 1st
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

24. More likely to be a Brown Roof?
Kangaroo and Wallaby grasses
with everlastings
Brenneisen S. 2006. Space for
Urban Wildlife: Designing Green
Roofs as Habitats in Switzerland.
Urban Habitats 4: 27-36.
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

25. Key Questions - Water
• 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?
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

26. Key Questions – Energy and lifecycle
• 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?
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

27. 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 conditions
2. Develop a locally produced light weight
substrate
3. Investigate the effect of the green roof on
building energy budgets
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

28. Green Roof Research @
The University of Melbourne
• 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

29. Green Roof Research @
The University of Melbourne
• Green Roof system
donated by ZinCo
• Used the FloraDrain
40 system
• 125 mm of substrate
Source:Zinco Planning Guide, 6th edition & Environment
Dr Nick Williams, Melbourne School of Land Green Roofs Australia Brisbane June 2008

30. Green Roof Research @
The University of Melbourne
• Green Roof system
was donated by
ZinCo
• Used the FloraDrain
125 mm
40 system
• 125 mm of substrate 40 mm
Dr Nick Williams, Melbourne School of Land & Environment Source:ZincoRoofs Australia Brisbane June 2008
Green Planning Guide, 6th edition

31. Root resistant water proofing
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

32. Fitting eaves to frame
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

33. Rolling out
protection layer
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

34. Adding
drainage
layer
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

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

36. Green Roof Research @
The University of Melbourne
• 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

37. Plant Selection Criteria
• Attractive
• High tolerance to light
• High ‘drought’ tolerance
• Robust and moderate to high vigour
• Easily maintained
• Tolerate seasonal water logging?
• Possum proof?
• Available
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

38. Habitat Templates
Gibber Chenopod Shrublands
Image: Rob Jung
Alpine rocky slopes
Native grasslands.
Photo Georgia Garrard
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

39. Potential Plant Species
Lomandra multiflora subsp. dura
Rounded Noon Flower
(Disphyma crassifolium)
Wallaby Grasses
(Austrodanthonia sp)
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

40. Potential Plant Species
Rhodanthe floribunda
Sedum mexicanum
Enchylaena
tomentosa
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

41. Potential Plant Species
Pigface (Carpobrotus Blue Chalk Sticks
rossii) (Kleinia mandraliscae)
Dianella
Phormium
revoluta
‘Thumbelina’
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

42. Potential Plant Species
? √
Pigface (Carpobrotus Blue Chalk Sticks
rossii) (Kleinia mandraliscae)
X Dianella
revoluta
X Phormium
‘Thumbelina’
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

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

44. CH2 East Core Roof – February 2008
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

45. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

46. 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
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008

47. Acknowledgements
• John and Kirsten
• Funding provided by The University of
Melbourne-CSIRO Collaborative grant
scheme
• Materials provided by ZinCO
• Peter May
• Ross Payne
Dr Nick Williams, Melbourne School of Land & Environment Green Roofs Australia Brisbane June 2008