The combination of one of the strongest El Nino events on record and 2015 breaking all records for hot temperatures are among the factors strengthening the case for investments in green infrastructure.

In addition to the benefits tree canopy and other vegetation has for cooling the urban environment, multiple other reasons are being recognised. These include improved flood mitigation, increased community wellbeing, reducing economic losses and adding asset value for both private and public landowners.

Councillor Arron Wood, chair of the City of Melbourne Environmental Committee, says a survey of Melbourne CBD retailers following five days of maximum temperatures over 40 degrees in January 2015 revealed losses of around $10 million a day. The customers simply were not coming into the city, he says.

Cr Wood says the council’s Urban Forest Strategy is a key part of future-proofing the city against these kinds of impacts from climate change.

“Greenery is about how well a city functions as the climate gets hotter.”

A 202020 Vision partner organisation, over the last four years, council has planted 12,000 trees, particularly targeting public open space. It aims to achieve 40 per cent canopy cover, and currently manages around 77,000 trees.

It also released the Growing Green Guide, which aims to engage the private sector by providing technical guidance on creating green roofs, green walls and living facade elements.

Cr Wood says that where a developer has a site that does not allow for ground-level planting, turning the rooftops, walls and facades green will be important as the inner city densifies.

Council is also seizing any opportunities it can find to obtain more public open space for more plantings.

The target is for 24 new hectares of public open space to be created over the next four years. One project already being planned is to close half of the six-lane Southbank Boulevard, as it is not carrying the high capacity of vehicles it was designed for, and convert the former road into green space. Just that one project will add 2.4 hectares, Cr Wood says.

The council also has a developer contribution scheme that requires developers to either set aside between five to eight percent of a site as open space, or to make a cash payment based on development value.

The money goes into the council’s open space fund – and in the last quarter alone it received $4 million in developer contributions.

The benefits of capturing stormwater

One of the other aspects of the urban forest program is the need to manage stormwater as a resource. Currently, 25 per cent of the annual water needed for open space plants is from rainwater harvesting. Cr Wood says the target is to bring that up to 50 per cent.

Strategies have included the construction of a wetland in Royal Park that cleans stormwater using a biomimicry approach and then stores it to be used for irrigation, and the installation of under-street rainwater harvest and capture infrastructure.

“We should be mimicking natural processes, for example making sure rainfall is going into the ground,” Cr Wood says.

Permeable asphalt is currently being trialled, and permeable paving has been installed in Collins Street, he says.

“Flash flooding is one of our issues. Permeability allows the water to infiltrate and then it can be captured and used.”

The business case for green infrastructure

Many of the significant learnings of its evolving urban forest strategy have been distilled into a 10-step guide for other councils, released last year by the 202020 Vision. The How to Grow an Urban Forest Guide helps councils to establish the business case, and engage the community, Cr Woods says.

Council has also released research undertaken by Victoria University on the economic value of green infrastructure. Cr Wood says it has previously been difficult to put a value on green infrastructure compared to a footpath or road.

“We are constantly building the business case for green infrastructure.”

In the private sector, director of ASPECT Studios, Sacha Coles, says most sophisticated clients have over the past two years come to understand that investing in green infrastructure contributes to health, aesthetics and sustainability. It is also an investment in place, he says.

In the past, it had been hard to get people to pay for something they see no immediate return from, Coles says.

That culture is changing though, as the relationship between greening and sales returns has become clear.

The big systems approaches to greening cities in the long-term, he says, are a strategic investment in the future of our cities. It’s been a matter of “battling the perception that landscaping and greening is a cost.”

He says some of the large companies, such as Medibank, Google and some of the banks “have their fingers on the pulse” of urban greening and indoor greening.

“They have an appreciation of the cognitive benefits of closeness to greening – people work smarter,” Coles says.

“We find the pioneering businesses are all over it.”

Coles says there needs to be both public and private partnership to achieve policy aims in terms of increasing canopy cover. Councils, for example, own the majority of streets and can develop urban forestry strategies to build up canopy.

In the private sector, if the major investors in real estate stock also undertook substantial greening of their assets, they have the ability to completely alter the temperature of the city, he says.

Coles says green roofs should be mandated policy in all new developments in Australia, as it is in Singapore.

“That is the simple low-hanging fruit,” he says.

“And if you open [those roof spaces] up to the public, you would get a whole other network of public spaces through the city.”