Written by Vicki Holder
Auckland has been slower to catch on, says Simon Chamberlain of GreenAir, a green infrastructure and plantscape business in Grey Lynn, mainly because architects and designers are not sure what to do or where to go for information. But it will happen, he says.
As Auckland moves towards an estimated 2 million people in the early 2030s, and the Unitary Plan plan allows for 422,000 extra houses to be built over the next 25 years, with limits around the boundaries, the only way is up for many areas. There is less space on the ground, so policymakers, design practitioners, and the public must consider new ways to incorporate greenery into the urban landscape - for environmental, health and aesthetic reasons.
“They can help with insulation by controlling the temperature of the building, keeping heat in during winter and out in summer.”
Green roofs offer many benefits for future housing designs, says Simon. Many residential owners in Sydney benefit from lower energy costs by adding rooftop gardens.
Sydney’s adoption of the rooftop garden trend also helps with the urban heat island effect (UHIE), which sees higher temperatures recorded in cities compared with rural areas due to heat being generated and absorbed by buildings, pavement and vehicles.
Canadian research has shown that if eight percent of roofs were greened, ambient temperatures could drop by two degrees.
In addition, they attract wildlife and insects, which is fantastic for biodiversity, says Simon. Plus they can be beneficial in reducing and slowing storm water run-off. “All water that hits the roof normally goes into the storm water system. Green roofs can absorb the moisture and take away pollutants at the same time,” so polluting particles don’t enter the water system. This results in reduced stress on the city’s sewage systems.
Then there’s the socialization aspect. Gardens on top of buildings help buildings merge into the landscape and invite the residents to entertain, relax and hang out with friends, says Simon. “It’s more visually appealing for neighbours who look down on a garden instead of a bare roof. If I was looking at buying a house and someone had a green roof that I could look out on, I’d feel so much better.”
“ They are absolutely viable on ordinary residential homes. The roof top sits there unused, so you may as well use it for growing plants.”
He assures, the Council loves green roof concepts too. “If the developer puts a green roof into the early phase of a building design, there’s more chance of their getting Resource Consent.
They are very much in favour of such developments.
Roof gardens have already popped up on commercial buildings in Auckland like the award-winning function space ‘The Cloak’ at Auckland Airport, designed by architects Fearon Hay, which included a 208m2 green roof. With pitched roof faces in a windy location, it required technical design expertise using a pre-vegetated system with a selection of native New Zealand grasses, ground covers and sedum plants pre-grown in modules for four months prior to installation.
Auckland Council’s Karanga Kiosk information centre at Wynyard Quarter, is another project featuring a pre-vegetated system of tussocks and grasses, designed to reduce run-off by up to 75%.
GreenAir currently has three or four more “ large projects on the board. There will be more jobs including apartments coming up over the next few months or so. We’re looking at some major apartment projects with balconies,” he says.
To install a green roof, you need to consult a structural engineer to check the weight the roof can support. Waterproofing is required and must be in excellent condition. Several companies in Auckland can advise on and help create the specifications needed to establish a green roof, including Greenair.
Greenair works with Stormwater 360 which has developed a pre-vegetated, modular green roof system called LiveRoof, specifically designed to grow plants in a rooftop environment. It provides an instant green roof with mature plans and is ideal for both residential and commercial builds. LiveRoof gives instant benefits providing an evaporative cooling effect, maximum storm water retention and optimal aesthetics.