By Elmira Jamei
Those living in Melbourne’s west are experiencing hotter days. A lot of that comes down to the fact that historically the west has had significantly lower levels of green infrastructure than other areas of Melbourne. Over the last few decades, there has been a construction boom, and rapid increase in the number of large scale infrastructure projects. Melbourne airport runways, Westgate tunnel, and Footscray hospital to name a few.
In the natural environment, you have soil, grass, and trees which can provide shade, absorb heat, and retain water in the environment, but, when you replace this with buildings, roads, and infrastructures more heat can be absorbed, more radiation can be trapped, and no moisture can be retained to cool the city. This is the main reason why most cities experience ‘urban heat islands’ (UHI). Urban heat islands happen when the temperature in cities becomes substantially higher than in the outskirts.
Over the past few years, there have been a number of initiatives to cool Melbourne’s west and manage the heat to care for the people who live there, as the possibility of experiencing heatwaves is significantly higher than in the past. Heatwaves are becoming more frequent and longer in duration and intensity, not just because of global warming, but also because of the way we build our cities and built environments. ‘Greening the West’ is one of the initiatives that aims to enable communities in Melbourne’s west through the development of more green spaces.
We need more than just trees on nature strips
Melbourne’s western suburbs receive less rainfall than other parts of Melbourne meaning they’re drier and can experience warmer daytime temperatures. As the population increases, the demand for construction, housing, and infrastructure increases, therefore, there should be a balance between what we build (grey infrastructure), and the natural environment (green infrastructure).
Well-off suburbs historically have more green spaces. People with money can afford to live in suburbs that are well-established and have mature trees. Whereas, a lot of newly developed suburbs, particularly in the west, have lower levels of greenery, because the size of their lots is reduced, so more houses and fewer gardens are built. As a result these suburbs experience hotter summers, which can pose significant public health threats, especially to people with low socio-economy backgrounds, elders, and those with cardiovascular diseases.
In 2009, when black Friday happened, the temperature threshold in Melbourne’s west exceeded 47.5 °C, and not all communities were impacted in the same way. Hospital admissions during heatwaves are significantly higher for communities who live in disadvantaged areas. The number of events like Black Friday is rapidly increasing, so we need to be well-prepared.
Urban greening in the west is a low-cost strategy that not only cools the suburbs, but also provides health benefits for the residents who live there. Urban greening could be more than trees on the streets, it can be green roofs, green walls, parks, or even green pockets that connect neighbourhood’s activity centres.
Irrigation essential for success
Trees bring cooling benefits when they are mature and well-irrigated. Urban parks operate in the same way, they need water, and mature trees to cool the city. They provide local cooling and minimise the impact of heat on residents through the provision of shade. So, it is essential that we factor in adequate irrigation for long-term impact.
Green roofs and green walls are also good strategies to cool the suburbs, because they reflect the heat, rather than absorbing it. They can also save energy that is needed to cool buildings.
With the rapid growth in Melbourne’s west, there is a common interest in greening from a range of stakeholders, water corporations, local governments, and communities. What is needed now is the development of clear communication across these diverse sectors, and the finding a common language that enables strategic planning and implementation.
Dr. Elmira Jamei
Associate Professor (Built Environment)
Institute for Sustainable Industries and Liveable Cities
Victoria University
