An oasis of green amid the corrugated iron and terracotta tiled roofs of Sydney’s Inner West, the flowering green roof of Forest Lodge Eco House boasts a cracking view.
To the north, newly developed parkland offers rare bush views, while to the south is the familiar rise of suburban flats.
“You go up there and it looks beautiful,” says owner Chris Knierim, who runs a Sydney-based construction company, Designer Constructions, and also designed and built the house.
Knierim and his wife Belinda started building a new family home to share with their two sons –Dieter, 19, and Liam, 17 – on one of the City of Sydney’s last remaining vacant blocks in the inner-city suburb of Forest Lodge, after renovating the adjacent Victorian terrace, known as Foss Cottage.
“The City of Sydney Council advised that they would like to see a design that reflects today's contemporary architecture,” says Knierim. “That's all the input they had, the rest was up to me." Knierim’s aim was to design a contemporary house using modern materials, such as glass and steel, that was also as sustainable as possible. He wanted to showcase the sustainable construction techniques he learned while living and working in Europe, where environmentally friendly housing is the norm.
He has applied principles of sustainability to every detail of the terrace’s design and construction. Among the most spectacular is the seven-metre high vertical garden adorning the front of the house, and the flowering green roof that crowns it, which remarkably gives the house one square metre more green space than living space.
The green roof is beautiful, but it has an integral practical application as well. As insulation, the green roof is phenomenal, says Knierim.
He has designed it to be very light, which means less concrete and steel is required to hold it up. The soil used on the roof – at 100 millimetres, half the thickness normally used – is a custom mix made from ingredients including scoria, a volcanic rock that is porous and lightweight.
“Normal soil, when it rains, keeps compacting and eventually it’s like walking on concrete, and there are no nutrients left in it,” Knierim explains. “With scoria, the air can still flow through, so there are still gaps everywhere for the roots to grow.”
Perhaps one of the defining tests of a sustainable house is how it handles a heatwave, one the Forest Lodge terrace passed with flying colours during 39-degree days this summer.
“We put a ducted air-conditioning system in but we haven’t used it,” says Knierim. During the hottest days of the year the house felt warm, he says, but not hot enough to turn on the air-con, which he calculates equates to a saving of at least $3000 a year.
“The only reason we put it in was for retail value because if I try to sell a home worth over $1 million and it doesn’t have air-conditioning, people think, ‘Oh, I’m not going to buy it’,’” he laughs.
Instead, the house is cooled by a sophisticated cross-ventilation system, which uses double-glazed windows and internal blinds to control the flow of heat around the terrace.
Energy from rooftop solar tubes is used to heat the underground concrete slab, which doubles as a storage cell, providing thermal mass heating. Also underground is a 3500-litre tank which supplies water to the green roof and vertical gardens, as well as a water feature at the rear of the house which uses evaporative cooling to duct chilled air into internal spaces.
Recycled materials were used wherever possible. Knierim scoured demolition sites looking for old bricks for the build, while recycled content was mixed into the concrete as aggregate. Although expensive to install, LED striplights offer lighting that uses as much energy as just three 60-watt downlights.
It’s no surprise that the Eco House project has a number of fans. In 2013 the Forest Lodge Eco House appeared on popular architecture television series Grand Designs Australia, while in January, City of Sydney Lord Mayor Clover Moore, an outspoken advocate of green living, officially opened the house, cutting a green ribbon to mark the occasion of the Knierim family moving in.
Knierim believes that part of the reason sustainable construction isn’t more common in Australia is fear. “Everyone is scared,” he says. “But although it’s new here it’s not new.”
People are put off by the initial high cost of building sustainably, even though there are clear savings to be made over time.
It’s simple, according to Knierim. “If you can insulate your home properly your electricity bill will decrease.”
Chris Knierim runs Designer Constructions, a Sydney-based construction company.