Greening our rooftops
[ Research Review 0809 : ]
By Nerissa Hannink
With climate change predicted to bring higher temperatures and lower rainfall to large parts of Australia, researchers in the Departments of Resource Management & Geography and Forest & Ecosystem Science are investigating the potential of green infrastructure to adapt our cities and lessen these impacts.
Urban green infrastructure incorporates parks, gardens, urban agriculture, street trees and new technologies such as green roofs and green walls to reduce the energy demands of cities and create a more pleasant environment for its inhabitants.
Green roofs are roofs with vegetation growing in a lightweight designed substrate on a specialised drainage layer. They are a climate change adaptation technology that is widespread in Europe and North America, but is rarely used and still untested in Australia.
A recently awarded Australian Research Council Linkage Grant of $380,000 will develop green roofs suitable for the Australian climate. Dr Nick Williams, based at the School of Land and Environment‚€™s Burnley campus, is leading the project and says that Australian climatic conditions are different to those in the northern hemisphere, meaning that we can not easily import green roof substrates or plants from overseas and have to find our own solutions.
‚€œOur research will significantly progress the Australian green roof industry by overcoming barriers to their implementation,‚€Ě said Dr Williams.
‚€œHopefully this will lead to multiple environmental, economic and health benefits at a variety of scales.‚€Ě
Benefits of green roofs for individual buildings include greater energy efficiency, increased roof life and the attenuation of noise. Environmental benefits include biodiversity habitat, reduced volume and improved quality of stormwater flows and cooling of the urban environment through evapotranspiration. This further reduces urban energy use and greenhouse emissions, while reducing human health risks during heatwaves.
The project also involves Dr Stefan Arndt and Mr John Rayner and is co-funded by Melbourne Water, the Department of Sustainability and Environment, the City of Melbourne and the Committee for Melbourne.
The new grant will enable the development of new green roof substrates from Australian resources and will identify local plants that can survive the extreme conditions on green roofs.
The need for this research was demonstrated by the results of a pilot study at the Burnley campus which was established in July 2008.
‚€œAlmost all plant species that were planted on Australia‚€™s first experimental green roof died over the summer of 2008/2009,‚€Ě said Mr Rayner.
‚€œThe conditions were extreme this summer but our results demonstrate that further research to identify plants that can survive on Australian green roofs is a priority.‚€Ě
The research is also needed by local industries. ‚€œWe are constantly getting requests from architects and landscape architects who are keen to install green roofs on buildings. They need information on which plants work best and what substrates they can use,‚€Ě said Mr Rayner.
Other green infrastructure research being conducted by Dr Steve Livesley and colleagues in the School of Land and Environment includes investigations into the greenhouse gas balances of garden management. Studies include the measurement of carbon dioxide, methane and nitrogen dioxide fluxes in lawn versus mulched garden beds and the quantification of the environmental benefits of urban street trees.
A team led by Dr Geoff Connellan and Professor Nigel Stork at the Burnley campus has also launched a website called ‚€˜Smart Garden Watering‚€™: www.smartgardenwatering.org.au
The site helps gardeners work out the best species for their location, calculate the amount of water needed through the year and plan for water tanks to replace mains water. The website was designed by the University of Melbourne‚€™s Department of Information Systems with support from the Smart Water Fund.
This leading-edge research into green infrastructure is providing a new focus for the Burnley campus, putting it at the forefront of urban sustainability.
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