by Boris Kelly
12 October 2010 -FAVOURITES – Green roofs have long been used in the rural regions of Scandinavia. Commonly termed “sod roofs”, they provided excellent drainage and insulation properties and were ideally suited to the cold climate. The materials used in the roofs included birch bark, with its excellent water-resistant properties, and various species of turf.
These days, 21st Century green roofs have emerged as an increasingly popular option used by architects, builders and landscape designers as a construction solution that combines aesthetics with functionality.
According to Sidonie Carpenter, president of Green Roofs Australia , which is holding its annual conference in Adelaide on 22-23 October, green roofs also have a great deal to contribute to climate change action and environmental sustainability.
The organisation describes a green roof system as an extension of a building’s existing roof. It involves a high quality water proofing and root repellent system, a drainage system, filter cloth, a lightweight growing medium and plants. But it can also be a rooftop food production system that meshes the technologies of aquaponics, vermiculture, rooftop water harvesting, and solar-powered air moisture harvesting. (See this website)
Cartpenter says it was the drought that inspired her interest in this specialist branch of landscape design. “I have always been interested in the environment and nature”, says Carpenter, ”and it was a move back to Brisbane during a period of Category 5 water restrictions when I started to look into ways that the landscape industry might survive if the drought continued. Who was going to employ a landscape architect/horticulturalist to design their garden when you couldn’t even keep your garden alive? So this is when I found green roofs.”
Carpenter formed her own company, Green Canopy, and got on with the job of designing and installing green roofs. She became involved with the non-profit Green Roofs Australia where she found fellow travellers in architects and engineers also interested in new ways of using the old methods of green roof design. She was awarded an ISSI and Pratt Foundation, Specialised Skills Fellowship in 2006, to travel and study the design, implementation and benefits of green roofs and living walls.
“I’m a landscape architect and horticulturalist,” Carpenter explains. “ I mainly do residential projects. My passion is working directly with clients to ensure they get exactly what they dream of. It’s very rewarding to have clients ringing years down the track to tell you how much they enjoy their gardens.”
And it seems more and more people are interested in incorporating green roofs and walls into their buildings. Australia’s Parliament House building is an example of a large scale, living roof and is highly regarded in international circles for its innovative design.
Among the environmental benefits of green roofs is their capacity to reduce storm water run off through natural absorption and filtration. Because they have a capacity to absorb solar heat, green roofs can also contribute to a reduction in the “heat island” effect caused by reflective surfaces in densely built up urban areas and their excellent insulating properties mean they can reduce the need for heating and cooling systems that rely on fossil fuel consumption. They look good too and can provide wonderful recreational spaces. Carpenter points out that a green roof using indigenous plant species capable of handling the harsh Australian climate can create a stunning visual impact on buildings and are increasingly being used by leading architectural firms in large and small scale projects.
“The challenges are really no different to designing a normal garden,” Carpenter says. “If you take your soils, their depth and the environmental conditions and design accordingly you should have a successful green roof. The problem in Australia is that people are taking guidelines from Germany and examples from the US when we have nothing in common with their climate or plant species. This is where we will see problems. We need to design for our climate and buildings and use our plant species.”
This year’s conference, the association’s fourth, will be an indication of how fast the industry is growing in Australia, Carpenter says.
“We have had a record number of papers submitted from local and international speakers, with a number of great Australian green roof examples to show and discuss. We have a fantastic green roof and wall walking tour and two education courses.
“This is our fourth annual conference and each year they are more inspiring and an indication of just how quickly the industry is growing here in Australia. Anyone who is interested in green roofs and walls from a design, construction and maintenance point of view should attend we are encouraging councils to attend as they need to get an understanding of where and how green roofs and walls will fit into the future of the Australian design and construction industries.”
Judging from Carpenter’s enthusiasm, there will be plenty of interest still to come.