INCREASING the number of trees in an urban area can have a big impact in reducing heat according to University of Technology Sydney researcher Dr Brent Jacobs.
At the December 12 Council meeting, councillors voted to receive a report on ways to naturally cool down the Hawkesbury, and that will involve looking at Dr Jacobs’ work.
Dr Jacobs is an associate professor and research director working at the Institute for Sustainable Futures, and some of his research has been done in the Penrith and Leichhardt.
Dr Jacobs and his team created heat maps with Google maps to look for hot spots, or heat islands, in those areas, and then visited each site to see exactly why they were so hot.
The research led to Penrith Council’s Cooling the City Strategy. Blacktown Council has a similar strategy called Cool Streets and Hawkesbury Council will potentially emulate these strategies.
One of the conclusions Dr Jacobs has drawn from his studies is increased tree cover over an entire suburb can effectively keep it cooler.
“All vegetation, provided it is well supplied with water, will have some effect on cooling the environment because it dissipates heat when water evaporates from leaves,” he said.
“Trees are particularly useful because they provide shade for the ground surface and other vegetation that is beneath their canopy as well as keeping themselves cool by through evapotranspiration.”
Dr Jacobs said recent research suggested introduced trees were the best because they had denser shade cover, less chance of leaves falling and were decidious, meaning sun hit the ground in winter among other benefits.
Sometimes it is impossible to plant more trees, and Dr Jacobs said there were solutions to this problem too.
He said light coloured materials reflected, rather than absorbed, heat, while permeable concrete let water cool an area in an effect similar to evapotranspiration.
Planning laws could also be altered to encourage the planting of green spaces across a neighbourhood he added.
“Trying get developers to embrace the need to incorporate vegetation and water sensitive urban design into green fields sites is difficult when there is pressure for ‘affordable’ housing,” he said.
“The upfront costs may be less but there are long term costs of urban heat islands that aren’t factored in – such as energy use, human health and well being benefits.”
He said parks only cooled an area locally, whereas increased tree canopy across a large area had a greater and more wide spread effect.
“Finally, people vary in their views on trees – some love them and value the benefits they bring, others see only leaf drop, loss of parking spaces, and security problems and resist when Councils undertake tree planting programs,” he said.