Greening Our Cities
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Urban greening is being used as a climate adaption tool to tackle both heatwaves and floods in cities.
A single tree can have the cooling power of more than ten air-conditioning units and research is also showing that there are health and wellbeing benefits from the visual presence of nature alone.
Green infrastructure is more than parks and trees on footpaths and street medians. It can also look like green roofs, living walls and community gardens. But an exemplary greening initiative in one city may not be the best solution for another.
The research team behind the Nature report Global climate-driven trade-offs between the water retention and cooling benefits of urban greening created a data-driven analysis to understand and create a way to scope the potential of urban greening to mitigate for heat and flood-related climate risks.
“Policymakers worldwide can use our results as a first-pass guide for more local feasibility studies on urban greening. While it’s a crucial planning and climate change adaptation tool, urban greening has to be understood within specific local conditions – one size does not fit all,” they shared.
We can see these differences from city to city in Australia. Melbourne is a great example of a city that benefits from greening initiatives to mitigate temperature increases. Canberra, Adelaide, Perth and Brisbane are water-limited. According to the researchers’ modelling, urban greening is ineffective at reducing the urban heat island effect in these cities but can help reduce flash flooding. Darwin is Australia’s only state capital that they recommend would not derive strong stormwater or cooling benefits from urban greening.
Stuttgart
Stuttgart is known as the green roof capital of Europe. Green roofs became a widely implemented tool for combating poor air quality and excessive heat in the city and have been mandated for many buildings since 1986. The federal German building code requires green roofs on all developments with a roof slope of less than 12 degrees.
Incentives in the form of reimbursements are offered for existing buildings or new buildings when the construction plan doesn’t require a green roof. Between 1986 and 2009, 430 projects (66,000 m2) received subsidies covering 50% of the cost of installation and materials. The European Federation of Green Roof Associations estimates that as of 2014 Germany had 86 million m2 of green roofs with 8 million m2 added each year.
Toronto
Toronto implemented a mandatory green roof regulation for all new commercial, residential and institutional buildings with a gross floor area greater than 2,000 m2. The Green Roof Bylaw requires that a minimum of 20% of available roof space must have green cover. City buildings require a minimum 50% cover.
Toronto’s green roof policies have delivered incredible results with electricity savings for the buildings with green roofs as well as surrounding buildings due to a reduction in the urban heat island. It has also stimulated the local economy with almost 2,000 jobs created in construction and maintenance.
Sydney
Junglefy created a tropical environment in the heart of Sydney with the Southern Hemisphere’s highest man-made waterfall along with a green wall of 5,736 plants across 139m2.
This incredible visual feature has wide-ranging environmental benefits including urban heat and carbon reduction. The four bespoke green walls can be controlled independently to cater for variances in wind conditions and achieve the best outcome for the garden.
Singapore
Singapore is a partner city in the Biophilic Cities Network and is a fantastic example of how to integrate nature into building and city designs. The team behind the Parkroyal on Pickering Hotel introduced 15,000 square metres of green space, which is equal in size to the neighbouring Hong Lim Park. The forested terraces, waterfalls and sky gardens are now inhabited by local birds, butterflies, insects and bees.
Cities with a rapid uptake of green roofs, walls and facades have clear strategies and policies combined with incentives and regulation. Tailored policies can produce green infrastructure that deals with the specific impacts of urbanisation and climate change in that region, such as stormwater runoff in flood-prone catchments. Education and advocacy for urban greening initiatives makes sure that we can maintain standards of design and installation to reach green cover goals and keep innovating.
