News

The cool green roofs taking over from the ‘dumb hat’

September 28th, 2023

In Sydney’s northern beaches, a new home with a green roof filled by native plants and cascading vines is hot trendwise, but inside it’s cool, calm and comfortable on a steamy summer’s day.

After architect Thomas Martin of Rama Architects completed M House at Clareville last June, several new clients called wanting something similar.

The home disappears into a hill under a lush green roof, a courtyard and gardens mixing Australian native trees with large elephant ears (Colocasia) and palms.

A local take on Brazilian modernism, the family home is shortlisted for two awards this year; the best new house by the NSW Chapter of the Australian Institute of Architects and the Australian Interior Design Award.

To Sydney architect Shaun Carter, the roof, sometimes called “the fifth facade”, has been treated like a “dumb hat” for too long considering it accounts for about 50 per cent of potential landscape on a site. “A green roof collects water, acts like an insect hotel, and does a lot of cooling,” he said.

After the Scandi-modern home Bunkeren near Newcastle won major architecture awards in 2021, it was posted on YouTube by architecture publication, the Local Project, with the tagline: Is This the Best Modern House in the World?

Described as more landscape than home by its architect James Stockwell, millions watched the video, thousands commented, and dozens contacted Stockwell asking him to design something similar.

Green roofs are a way of life for Stockwell, whose “earth studio” in the Blue Mountains is about to be planted with tulips for spring. They replace summer’s strawberries.

On the hotter days of the year, most rooftops in Sydney will reach 50 degrees and beyond, says Dr Peter Irga, an atmospheric scientist in the University of Technology Sydney’s Faculty of Engineering.

Bunkers, Utzon and a little bit of Denmark in Newcastle

A green roof, anything about 10 to 15 centimetres deep with soil, plants and a growing mat, can reduce surface temperature by as much as 20 degrees, a study by Irga and colleagues Fraser Torpy and Robert Fleck found.

They compared two roofs in Sydney’s Barangaroo over a year. One had solar panels and was also planted with 15 different native species that flowered at different times of the year. The other only had solar panels.

Irga says a green roof cools the roof temperature, the ambient temperature nearby and reduces the energy needs of a building. When the weather was cold, minimum daily temperatures on the green roof were higher than those on the conventional roof.

The 15 native plants on the rooftop attracted birds and insects, ranging from Australian stingless bees, spotted doves and evidence of a peregrine falcon.

Irga also spotted an Australian blue banded bee, a solitary and beautiful bee that is rarely seen. “It blew everyone’s minds,” he said.

For the full story, please visit – https://www.smh.com.au/culture/art-and-design/the-cool-green-roofs-taking-over-from-the-dumb-hat-20230404-p5cxxz.html