Sky gardens and green cities

By Oryana Angel 12 June 2015
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Amid the buzz and the grind of our biggest metropolises, more and more sky gardens are beginning to bloom

I am in Sydney’s Pyrmont, one of the nation’s most densely populated suburbs. Here, four lanes of Harris Street meet the overpass for the Western Distributor freeway and the Cross City Tunnel. This is one of the busiest thoroughfares in Australia, yet I am strolling around a peaceful oasis. It’s a spacious -garden about half the size of a rugby field, but it’s not where you’d expect it to be. We are six storeys high on the roof of a heritage-listed residential building called M Central.

“It’s an island in the sky,” says Daniel Baffsky, principal at 360 Landscape Architects, who designed the 2600sq.m communal space. “In an intense urban environment people need a place to be immersed in nature.” The garden was influenced by Brazilian modernism, but its gentle water feature, wooden walkways and swaying pennisetum native grass make it feel minimalist to me. It’s a little Japanese, reminiscent of Berlin and, oh, so Sydney.

“I’m happy to see it looking so good,” says Daniel, who hasn’t visited the garden for about three years. He is pleased that, without his supervision, it is blooming. “To survive on a rooftop, plants need to be hardy and low maintenance – bulletproof.”

Exposure to harsh sun, little natural shade and a lot of wind mean that rooftops can be hostile environments. This one has a range of native species and succulents, a mix that clearly works. The garden was retrofitted onto the existing building in 2005 and the only damage to the ground cover appears to be from frolicking dogs. While I’m in the garden, two of the 400-plus people living in the building arrive to walk their pooches.

We talk with Mina Choi, who brings her tiny white shih tzu-maltese terrier here to stretch its legs four or five times a day. “We take her up here early in the morning, after breakfast, at lunch, before dinner and at night,” says Mina, 35, who bought the apartment with her husband in 2010, largely because of the pet-friendly rooftop garden. “It’s a nice place to walk the dog. There’s a great view.”

Children and other families living in the building also enjoy the rooftop sanctuary. On the far western side there’s a softball court, paths to ride scooters, deck chairs, barbecue facilities, a huge community centre and more great views to boot.

Sky gardens and green roofs in Australia

Although Australia lacks the rooftop-garden and green-roof culture that’s become deep-rooted in Europe and North America, green roofs are gradually creeping across our biggest cities. The City of Sydney (from Newtown and Annandale in the west, to Elizabeth Bay and Rosebery in the east) has more than 96,000sq.m of green walls and roofs. This includes more than 50 green roofs and 25-plus green walls, and the council receives a new development application every week. In central Melbourne, the movement has progressed even further, and there are about 100 green roofs, 50 green walls and hundreds of green facades. 

The City of Sydney council’s senior project officer for green roofs and walls, Lucy Sharman, says interest has spiked in the past 18 months. “The city is becoming more densely populated. Almost three-quarters of residents are living in high-rise apartments – people are keen to be around greenery.”

University of Melbourne senior lecturer in urban horticulture John Rayner says there’s no shortage of research pointing to the social and psychological benefits of access to green spaces in the city. “People like them; it adds to the green open space not available at ground level. [They] are healthier, happier and take less sick days simply because they are looking out at a green roof that could cost only $250 a square metre.”

One rooftop garden spreading happiness is the vegetable patch that thrives atop the Wayside Chapel in Potts Point, on the fringes of the Kings Cross red-light district. From there, looking over a curtain of piquantly scented wild passionfruit, I see the Sydney CBD skyline punctuated by skyscrapers and Sydney Tower. In the other direction is another rooftop garden on Macleay Street. Otherwise, there are just a whole lot of empty rooftops and tired air-conditioner systems rattling away in the heat.

During my visit to this drop-in centre for the homeless, mentally ill, addicts and other down-and-outs, it’s hard to know who is a visitor and who is a volunteer – everyone seems to be buzzing around, empowered by their role in the project.

Rick ‘Pee Wee’ Geoff, 77, strides purposefully among the organic eggplant, tomato, warrigal greens, finger limes and native mint. His job is to water the plants and he lingers at his favourite – the curry plant. “I love my pillow plant,” he says of the soft, silver-hued herb, which I find to be pleasingly soft when I’m prompted to cuddle it. “I like participating. As long as they need me, I’ll keep coming. There’s nowhere else I can come like this.”

The rooftop vegie garden was brought to life two years ago by Wayside program manager Wendy Suma who wanted to create a green space for disadvantaged people and locals to share. “The garden is flourishing but also the gardeners are flourishing,” she says.

Wayside’s produce gets put to good use, supplying the third floor for cooking lessons and then it’s served up in the bustling ground-floor cafe. There are also two large beehives, home to some 180,000 bees, and an efficient compost system, which ensures the plants get the nutrients they need.

Environmental benefits of sky gardens

AS CITIES GROW warmer because of climate change, green roofs and walls can relieve stifling urban conditions. Concrete and asphalt absorb much more radiation than foliage, resulting in more energy required for air-conditioning. And heat-related illness is becoming more common.

“There are many more air conditioners running in urban areas than we had a decade ago. The costs in energy and latent heat produced are enormous,” John says. “Other ways of cooling are becoming a necessity, not a luxury.”

The thermal benefits of an irrigated green roof can mean significant energy savings. By providing shade and insulation, such roofs keep buildings warm in winter and cool in summer. A 2009 joint University of Melbourne and CSIRO study found that green roofs can reduce cooling costs by as much as 50 per cent, compared with a conventional concrete and bitumen roof.

Another reason many cities are investing in green roofs is to help cope with stormwater. “A deep, green roof, with a large surface area and lots of plants and soil, can absorb up to 80 per cent of rainfall that falls on it,” John says. “Even a shallow green roof, 10cm deep, can hold 50 per cent of the rainfall.”

Following the disastrous flooding in the wake of Hurricane Sandy in 2012, New York City – with its abundance of hard concrete surfaces – is now investing in parks and green roofs. These act like giant sponges to soak up stormwater run-off.

Future innovations in green roofs and sky gardens

It’s not only green roofs causing a stir around the world. Green facades, vertical gardens and climbing plants can have an even greater environmental impact on a high-rise building due to the sheer amount of space available for coverage. A study conducted in Spain in 2011 looked at the effects of green facades on a building surface and its ambient temperatures. It showed that, during summer, buildings with a wall covered by a climbing plant were up to 15 degrees cooler than those without.

In Chippendale, in Sydney’s inner west, a futuristic $2 billion development can be found on the former Carlton and United brewery site. The residential towers of the One Central Park development (the tallest of which is 33 storeys) are draped in soaring vertical gardens – swathes of acacia, dianella, lomandra and viola.

The 21 panels were designed by French horticulturalist and artist Patrick Blanc and the tallest, which cascades 42m down the western face, is believed to be the largest vertical garden in the word. The flamboyant Parisian (think green hair and long green fingernails), who does nothing by small measures, is recognised for starting the hugely popular vertical-garden movement.

“It’s innovation on a massive scale,” says Mick Caddey, One Central Park’s project director. The towers are covered by 2700 horizontal planter boxes, housing tens of thousands of individual plants. Half the balconies have vertical wires to encourage the vines to eventually cover the space.

“Once they have established, it will look more like a green box than a building,” Mick says. “One Central Park’s green walls by themselves aren’t going to make massive environmental changes. But in aggregate, there’s no doubt that the green walls and horizontal planters here will contribute to the whole green-city initiative.”

Dr Brent Jacobs, research director of the University of Technology Sydney’s Institute for Sustainable Futures, predicts that in 100 years most high-rise residential buildings will have green roofs and walls. “There’s been growth in this style of architecture in Australia because people are beginning to see the benefits,” he says. “Green roofs and walls are also gaining acceptance by builders and designers.”

Matthew Dillon, the Sydney president of industry body Green Roofs Australasia, says that increasing demand, supporting research and an urgency to act sooner rather than later are all helping to drive green roofs’ popularity. Nevertheless, he says the transition from grey to green is slow due to the perceived cost and risks, scepticism about climate change, a lack of mandated policy and global economic instability.

“For capital cities, going green requires a systemic approach,” Matthew says. Such a strategy includes a range of tactics, from an overhaul of environmental education to more community engagement. This is what has happened in other cities around the world, such as Berlin, Linz, Toronto and Portland. All have successfully implemented urban green-roof and wall initiatives over the past decades.

In the US, Chicago leads the movement. Back at the turn of the millennium, former mayor Richard Daley started a green renaissance by throwing money at any project that incorporated a green roof in its development plan.

Now, almost 15 years later, Millennium Park and City Hall are just two of the city’s famous roofs. By 2009, Chicago had green roofs covering several million square metres.

That all sounds really impressive until you look at European countries such as Germany, where green-roof traditions date from more than 100 years ago and gained momentum in the 1970s as stormwater problems prompted development of the technology and then an industry.

Experts say about 15 per cent of all flat roofs in Germany are green; that’s about 1 billion square metres. And about 10 million square metres worth of new green roofs are added each year.

Australian sky garden industry

The local industry is in its infancy but heading in the right direction. The City of Melbourne’s Growing Green Guide, released in February, is an initiative to help everyone from architects and landscape designers, to DIYers and councils in implementing a green roof or wall.

“In Australia we don’t have planning guidelines for different types of green roofs and walls. When an application comes through we need to understand if the proposed design of the green roof or wall will actually survive,” says Gail Hall, the City of Melbourne’s project coordinator for urban landscapes.

The Venny is a green roof built atop a community facility at Melbourne’s JJ Holland Park in Kensington. The centre has two green roofs on converted shipping containers: a lower flat roof with planting designed around three sections and an upper sloping roof.

“It demonstrated that you can put a green roof on a typical Australian sloping roof,” Gail says. “They’ve been doing that in other countries but Australia has a very dry climate and we wanted to show that the plants would survive here.”

Australia’s largest green-roof project, using lightweight materials, is the 26,000sq.m green roof on the desalination plant at Wonthaggi, 115km south-east of Melbourne. It is not only the largest green roof in the Southern Hemisphere, it is also built on 25mm-thick plywood.

“Our biggest innovation is being able to reduce the weight to the point where we can use less expensive structures to keep it up,” says Stuart Tyler, the national sales manager of Fytogreen, an Australian company specialising in green roofs and vertical gardens. “Now that we’ve done something at the scale of the desalination plant, we can build the technology into all residential designs.”

Fytogreen is also behind many of the most prominent local green-roof projects, among the 100 or so with which it is involved. It installed three at -Adelaide Zoo, one of which shelters permanent tents for overnight stays by schoolchildren. Then there is the Museum of Old and New Art’s (MONA’s) 1400sq.m roof garden spread over five roofs in Hobart and the 25 vertical garden sections on Channel 9’s reality TV show The Block: Sky High.

ONE OF AUSTRALIA’S oldest green roofs tops the former Reader’s Digest Building in Surry Hills, Sydney. From street level, you’d never guess its roof supports a large garden, with soaring 50-year-old casuarina and melaleuca trees.

“The garden hasn’t changed much. I remember all these trees – just one or two of the big ones are gone,” says John James, 83, the architect who designed the building in 1963. “The city is denuded of nature. I thought, ‘How can I bring nature into the building?’ At the time people didn’t understand what I was doing, they were definitely concerned the roof would leak.”

Under each of the trees, which are now more than 15m high, John strategically placed a supporting column. The garden is on a waterproof membrane – turned up on all sides like a giant bathtub – above a reinforced concrete slab. It definitely wasn’t a typical 1960s building. But then nothing about the off-form concrete building is traditional, and neither is John for that matter. “I suppose I am unconventional,” he says, laughing.

Despite naysayers’ concerns, the original roof lasted 35 years. In 2000 it was replaced and the garden reinstalled, at a great expense. A few years ago there was a period when the plants were supposedly neglected, but the current lessees are taking care of the garden – obviously enjoying the fact that they have the peaceful and very private space at their disposal.

A few kilometres away, back in Pyrmont on the tranquil rooftop of M Central, it’s hard to imagine that eight years ago, this beautiful green space was yet just another floor of the building’s 432-lot car park. With at least 70 per cent of buildings set to remain on the landscape over the next 50 years, the experts say the biggest impediment – or possibility – for the industry to really take off here is in retrofitting current buildings such as this one.
“Because of that we need to ensure it’s not only the new buildings that come through with green spaces,” Gail Hall says. “Retrofitting is somewhere we need to see progress with in the future to effect large-scale change.”