In the largest example on a council-owned building, Auckland Council has installed a living ‘green roof’ featuring more than 2000 plants on top of the central Auckland Library.
Mayor Phil Goff hopes the green roof will prompt other central Auckland property owners to consider the benefits of green infrastructure.
“As part of essential repair work to the library roof, Auckland Council took the opportunity to install plants as an alternative top layer to the usual stone ballast,” he says.
“The living roof will have a range of benefits, including reducing stormwater runoff, improving air quality, protecting the roof membrane from solar damage, and increasing biodiversity and habitat opportunities for insects and birds.
“It will be an example to other property owners in the central city to investigate installing green infrastructure, which as well as the environmental benefits, will help make our city centre a more pleasant place to work, shop and visit.”
“The living roof will also complement the council’s other climate change projects, such as those proposed through the Climate Action Targeted Rate, which will reduce emissions while delivering low emissions ferries, better public transport, improved walking and cycling infrastructure and thousands of large native trees in areas that currently lack green canopy cover.”
Local iwi Ngāti Whātua Ōrākei developed the roof design inspired by whāriki, a plaiting style of weaving representing the laying of foundations for all that it bears.
“You can see a pattern known as 'poutama' which represents education, progress, and ascension. It pays homage to the library as a place where people seek greater knowledge and understanding,” says Ngāti Whātua Ōrākei artist Hinengarangi Makoare.
Ngāti Whātua Ōrākei’s nursery propagated suitable native plant species for the exposed roof environment.
“Living roofs are becoming more desirable internationally due to the benefits they offer cities,” says Craig Mcilroy, General Manager Healthy Waters.
“Not only do they contribute to carbon dioxide reduction, but they also bring additional environmental, economic, and social wellbeing benefits.
"These might be providing better stormwater management; reduction in a building’s energy demand and increasing biodiversity opportunities in the city environs.
“A range of benefits will be monitored, reported on, and shared publicly, and we hope this will help others learn from this project and be inspired by living infrastructure,” he adds.
The remedial roof work for the library, which was delayed by COVID-19, cost around $10 million, with an additional $730,000 for the installation of the living roof.
A total of 2050 low-maintenance, hardy native plants have been planted in 'eco-pillows' designed to incorporate a mix of soil and nutrients and prevent soil particles and sediment from filtering into drainage and stormwater systems. An additional 300 to 400 plants will be planted over the coming months to improve overall coverage.