A cool change is coming to city streets

Our cities are heating up and we need to find innovative ways to lower urban temperatures, or life will become increasingly harder for residents. In Adelaide, the number of days when outdoor temperatures soared above 40°C increased from only two days per year in 2000 to six days per year in 2020.

Green Urban Futures is a multidisciplinary team of researchers from all five faculties who have united under the umbrella of the Environment Institute at the University of Adelaide, to investigate a range of ways to reduce urban heat, including increasing urban greenery.

Dr Ehsan Sharifi of the School of Architecture and Built Environment said their modelling showed that increasing Adelaide’s inner city tree canopy by 30% will reduce surface temperatures by 3°C in summer.

“This will lead to a reduction of around 140,000 tone of total carbon emission annually compared to a business-as-usual scenario.” Dr Sharifi added.

A similar study in the New South Wales suburb of Parramatta, involving Dr Carlos Bartesaghi-Koc also from the School of Architecture and Built Environment working with researchers from The University of New South Wales found a combination of increasing greenery and different design and building approaches will reduce ambient temperatures by up to 3.3°C and surface temperature by 30.9°C.

“Our findings show that a combination of increasing greenery, using reflective materials, employing spray systems, and applying shading structures is an effective strategy,” says Dr Bartesaghi-Koc, “it provides a very significant reduction of ambient temperature in CBD areas like Parramatta.”

But increasing greenery to mitigate urban heat is not without challenges. So, Dr Ehsan Sharifi, together with Professor Bob Hill, Director of the Environment Institute and Dr Kate Delaporte, Curator of the Waite Arboretum, have been working with Professor James Hayter, School of Architecture & Built Environment and President of the International Federation of Landscape Architects, to develop a multiple-criteria street tree selection database.

“The tool helps practitioners make informed decisions on what trees to plant where in the Greater Adelaide Metropolitan region,” says Dr Delaporte. “It takes into account factors such as maintenance, tolerance to drought, allergenicity, weed potential, as well as the tree and root structures.”

Planning and designing buildings that better address urban heat is another necessary step to achieve green urban cities. Buildings contribute around 20% of total greenhouse gas emissions, caused by the energy use for cooling/heating spaces and water.

Smarter site planning, more green space around buildings and well-designed buildings can help reduce cooling energy as well as improve the comfort, health and well-being of the occupants. This is particularly critical for people who are more vulnerable to extreme temperatures, such as older people, people with disability and people with low socio-economic status.

A recent ARC Discovery Project led by Professor Veronica Soebarto of the School of Architecture and Built Environment, found a significant correlation between temperatures and the perceived health and well-being of older people in South Australia.

“Indoor temperatures above 28°C and below 15°C are perceived to reduce older-people’s health and well-being,” says Professor Soebarto. “Our guideline to improve the thermal comfort in housing of older people in South Australia is due to be made publicly available by the end of 2021.”

The research has highlighted that the community needs to be part of discussions and decision making, in particular those at higher risk of the impact of extreme temperatures.

Critically, Professor Melissa Nursey-Bray, of the School of Social Sciences, has been focusing on engaging communities to be part of environmental decision making, particularly in the context of climate change and biodiversity protection.  

What’s next?

An important aspect of the team’s research is creating the first national picture of the impact of climate change on human health.

The ARC Discovery Project led by Dr Peng Bi, Professor of Public Health, is investigating the impact of climate change on human health and will generate the first national picture of the climate attributable burden of diseases in Australia.

“This work is expected to provide scientific evidence to policy-makers,“ says Dr Bi, “it will help in the development, prioritisation and implementation of current and future climate change and health adaptation strategies.”

Every piece of work undertaken by this diverse group of researchers is adding another piece to the history making work of The Green Urban Futures group.