Green wall advocates have hit back at an attack from a leading architect on the value of green walls, citing energy savings and biodiversity benefits.
Green walls have come under fire with the national president of the Australian Institute of Architects, Richard Kirk, questioning their sustainability.
Green walls, or vertical gardens, have taken off in Australia, with many new developments now including them as a key marketing feature.
Mr Kirk, however, told The Australian newspaper on Thursday that they may become eyesores in the future.
“It will be interesting to see how well these green walls will last and stand the test of time,” he said.
While Mr Kirk said internal green walls had functional benefits in terms of air purification and aesthetics, he seemed to question the functional benefits of external “vertical gardens”.
“Certainly, introducing landscaping inside a building has a functional purpose in that it cleans the air and provides a visual relief in internal spaces,” he said.
“But where it’s just placed on the outside of a building, just to conceal a car park, it’s not a responsible use of how to make a city more green.”
The statement has caused upset among green wall advocates, who say there are many benefits to external green walls that have been ignored.
The One Central Park green wall was used to illustrate The Australian’s article, and is the tallest in the world.
Jock Gammon, founder of Junglefy, the company responsible for maintenance of the One Central Park green wall, told The Fifth Estate some comments in the article were “shortsighted” and failed to accurately depict the benefits of the technology.
Green walls, he said, provided a number of benefits aside from aesthetic value, and were key to greening efforts in city areas that did not have space for additional parkland, and where development was increasingly taking up that space.
He said currently unreleased research by Arup found heat load reduction in the order of 35 per cent attributable to the greenery’s cooling effects at One Central Park. Deployed more widely, he said there would be compound benefits due to a reduction in the urban heat island effect.
Increased biodiversity was another important factor. The Central Park green wall was now home to frogs, wasps, bees and even a family of peregrine falcons that “wouldn’t be there if there wasn’t the biodiversity, food sources and plants”.
“The bigger, forward thinking developers are looking beyond pure numbers and giving value to harder to value areas like biophilia and biodiversity,” Mr Gammon said.
For Central Park, even harder to measure is the value the green wall has had in making the development an icon.
“No one could have predicted how iconic this building would become, and certainly the vertical garden is a big part of the story,” Frasers Property Australia’s general manager for sustainability Paolo Bevilacqua told the Property Council last year.
He also listed benefits including increased worker productivity, plants as carbon sinks, minimising water runoff, improved air quality and increasing retail spend.
“How many other sustainability initiatives deliver as many co-benefits?”
National president of the Australian Institute of Landscape Architects Linda Corkery also noted a number of “economic, social, health and wellbeing benefits” from green walls.
“I absolutely agree with Richard Kirk that cities must continue to improve existing urban green space and parklands, and look for every opportunity to create more open space for city residents and visitors,” she said.
“However, there aren’t many developers who are likely to do this unless their development approval conditions require it. Wherever we have an opportunity to bring more green, more landscape into the city, we should be ensuring that happens. With increased development density, we must look for ways to continually renew urban ecological systems, and create more beautiful and liveable spaces.”
Is maintenance an issue?
Mr Kirk’s critique also took issue with the high maintenance costs of such green wall installations.
“Australia doesn’t have a low-cost labour market, and vertical gardens are very labour intensive,” he said.
“You don’t just set and forget.”
Horticulturalist Patrick Honan in 2015 estimated that it would cost almost $700,000 a year to maintain One Central Park’s green wall with its six full-time horticultural staff.
“Such a comparatively high level of input just for the sake of maintenance cannot be considered sustainable, as it is consuming resources like labour, money and fuel at a rate that is astoundingly high,” he said.
He also called out the water, energy and material use necessary for such a green wall, concluding that marketing such a system as sustainable was “almost offensive”.
Mr Gammon, while not able to reveal the actual maintenance costs, said the estimates were inflated.
He also said the costs would not be too dissimilar to maintaining parkland.
“Is it a bad thing that we have people maintaining or looking after gardens? People looking after parklands?”
Mr Gammon said the costs for both installing and maintaining green walls were coming down. One Central Park, for example, uses building maintenance units designed for window cleaning, which are generally only used a few times a month.
“They haven’t been designed for daily maintenance,” he said.
But new technology is making maintenance an easier prospect.
“It’s like with any new technology; the ancillary technology required for maintenance is still catching up.”
Research into more robust species is also keeping costs down.
More research needed
Dr Paul Osmond, director of the Sustainable Built Environment Program at UNSW, said the value of green walls over their lifecycle was still an open question.
“It’s a really good question and an area we are looking into more and more these days,” he told The Fifth Estate.
“From a service life perspective – from design, installation, maintenance, replacement of plants, water systems and even decommissioning – no one has really explored that.”
He did however say there was sustainability value in pure aesthetics, which he said was part of social sustainability. This included the value of nature in terms of biophilic responses such as stress reduction, particularly in otherwise built up areas like Central Park, where there was relatively little other opportunity for greening.
“It is a big social, educational and health benefit.”
A spokesperson for Mr Kirk said he had been accurately quoted in The Australian‘s article.
What are your thoughts on green walls? Important urban greening solution? Or expensive green wash?