Extract from ABC News
If you look down from Helen Baker's apartment balcony, you'll see big communal gardens filled with daises and olive trees, kangaroo paws and carpet roses.
What you won't see is the concrete slab most of the garden sits on.
"Looking down here, it just gives you so much joy," Helen explained.
Where she lives — at a retirement village in Aberfeldie in Melbourne's north-west — the rooftop garden sits on top of an underground car park and, like rooftop gardens at higher elevations, it is helping to solve a number of problems.
Rooftop gardens and green roofs — which can be shallow gardens used primarily for environmental purposes or deeper, larger gardens which can also be used as recreational spaces, have long been known for their range of environmental and wellbeing benefits.
Depending on their design, they can help cool hot urban environments, improve the energy efficiency of buildings, reduce stormwater runoff and flash flooding, improve air quality and biodiversity, and increase wellbeing of those who can access them.
But, despite their long list of possible benefits, experts acknowledge their take-up in Australia has generally been slow, and much slower than many comparable cities around the world.
Geoff Heard designed the Aberfeldie rooftop garden and says they can be challenging to build but they come with many benefits.
He says the retirement village garden at Aberfeldie has, for example, helped to reduce heat in an area that can be a bit of a "furnace" and has helped solve a problem of limited space.
And for residents like Helen, this unique garden has helped to overcome the sadness of leaving her own backyard to downsize to an apartment.
"I grew up in the country and mum and dad always had a garden, it was a produce garden, as well as for picking flowers," she remembers.
"When I came to the city, I guess gardening just followed."
While she waits for the rose bushes on her apartment balcony to grow, the communal garden has given her a place to once again smell the roses and pick flowers.
She's one of many to spruik the benefits of green roofs.
But, to get to the bottom of why these popular gardens haven't become a more common feature in Australia, we'll need to do a little digging.
Australia falling behind international cities when it comes to green roofs
Paul Osmond is a sustainable development researcher at the University of NSW and was a technical advisor to the City of Sydney when it developed its green roof policy nearly 10 years ago.
Back then, the Sydney CBD had about 40 green roofs, he says, which has now about doubled.
And while that sounds like an impressive jump, it remains such a small total that he says it puts Sydney well behind many international cities.
It is a similar story in Melbourne where, in 2019, deputy lord mayor Nicholas Reece wrote an impassioned piece in The Age newspaper calling for the city's buildings to add green roofs.
The City of Melbourne had mapped roofs across the CBD and found just 40 had a garden on top.
Today, he estimates that figure is between 50-60.
While there has been modest growth, Cr Reece wants to see that turbocharged around the country.
"Australia needs a green roof revolution, the unused rooftops of Australia's buildings are a massively underused resource that have the potential to create huge new green spaces in the centre of our biggest cities," he explains.
So, what needs to happen to bring about that revolution?
Cr Reece believes there are two factors that will drive a "great leap forward" — the first is people buying into multi-storey apartment buildings demanding that kind of green space be a part of their buildings.
The second he believes is regulation.
"Cities like Singapore, Toronto, Munich as well as Berlin, Chicago, London, Seattle, Tokyo and San Francisco, most recently New York have all created a greener city by introducing planning requirements that effectively mandate green roofs and green space in new developments," he explains.
"These cities are using incentive carrots and regulatory sticks to encourage more green space in private developments, and research across all international cities confirms the number of green roofs in these cities simply would not have occurred without these regulatory changes."
At elevation, designers say a garden can be trickier to build
Dr Osmond says there are still "barriers, both perceived and real" slowing the growth of garden rooftops.
One barrier, he says, has been support for this infrastructure — when Sydney Council was looking at the issue nearly a decade ago, he says, a study it commissioned showed the general public was more supportive of these green spaces than the development industry, which was worried about the practicalities.
"There was a lot of concern by industry about waterproofing and the liability of that, plant species selection, maintenance and ease of maintenance or not, and cost came up as a big barrier," he says.
Garden designer Geoff Heard says rooftop gardens can be challenging to build — the Aberfeldie garden, he explains, has a 400mm deep soil profile, so the garden "is floating over a slab".
It needed plants which could thrive at that depth and it was challenging to get materials to the garden, with only a small laneway for access.
Mr Heard says soil was blown in from trucks and planter boxes were made of aluminium, so they were light enough to carry in.
Another Melbourne landscape designer, Lisa Ellis, agrees building gardens above ground can be tricky.
"One of the biggest hurdles it is not even cost, funnily enough, for gardens on roof tops, it is the load limits," she says.
With roof top gardens, she explains, weight is everything.
"If I can make some comparisons for you — generally speaking a rooftop or terrace is engineered to accommodate between 200-400kg per square metre and that is dead load (constant load)," she explains.
But she says if a person saw a tree in a courtyard at ground level and wanted to emulate that same garden, it and the cubic metre of soil it would need would likely require a building which could accommodate a load of between 1,300 and 1,700kg per square metre.
"So that shows the enormous difference between gardening at true ground and at a rooftop," she says.
The designer says it is easier for rooftop gardens to be built as part of the original construction of a project rather than as a retrofit, because of these issues of load as well as waterproofing and problems with getting materials to a rooftop if a crane can't be used.
She says the benefits, though, can be life changing and could help attract more residents into our CBDs.
"A great garden will nourish the soul, it will be an escape from the stresses of life," she says.
"A really good garden can be a place where one can recharge and replenish."
Designers and experts say rules to need to change to push greener rooftops
Dr Osmond wants to see councils look abroad to countries and cities which have had greater success than Australia at greening rooftops.
He wants councils to consider planning regulations which require green roofs in circumstances where green space is lost to a development, but he thinks councils should consider incentives where developers could be allowed to build a slightly higher building if they include a green roof.
In Melbourne, Cr Reece says the City of Melbourne is working on a planning scheme amendment which aims to increase green infrastructure in buildings and improve energy efficiency.
Across the CBD, Cr Reece says buildings make up 66 per cent of emissions, so this amendment is something he sees as vital.
It will include a tool which will give developers a score for the amount of greenery (including green roofs) included in a building, with approval dependent on buildings meeting certain scores.
He hopes this will see a greater uptake of green roofs than the city has seen so far.
While back at Aberfeldie, Helen hopes more Australians have a chance to pick flowers and experience the joy of their own rooftop garden.
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