The client’s brief was for an autonomous building that har vested its own power and water and treated waste on-site. Zen Architects’ response to the brief was a house that uses the sun to pro vide most of its heating through passive solar design, and prevailing breezes to pro vide passive cooling.
One of the main challenges at the project was the 5 acre site. The landscape consisted of coastal scrub and height restrictions and a sloping site made it difficult to get the building out of the treetops to capture northern sunlight. In the end the building site was chosen where a tree had fallen over on a north slope leading to the creek, which allowed sunlight in.
“The aim of the project was to have as minimal impact on the bush as possible, which heavily influenced the siting of the building. Materials with low embodied energy were used and recycled where possible, such as the poles and straw bale,” Ric Zen says.
“Each room has been designed to capture southerly breezes, while having the added benefit of the stack effect which draws cool air in at the ground floor while flush ing hot air out at the top floor via a stair void, even when there is little air movement. This system works really well, particularly for night purging.”
The home also includes thermal mass through a groundfloor slab and 40 mm thick mud render with minimal concrete content. Straw bale walls on the ground floor also provide thermal stability throughout the year and walls and ceilings are well insulated.
Power to the property is provided via an 8 kilowatt PV array with a backup bio diesel generator, with the PV array also used for power during construction. Solar hot water was integrated with hydronic heating and boosted by a 25 kilowatt wood-fired stove boil er, cooktop and two ovens.
Other sustainability meas ures include 25,000 litre water tanks, which are double the required storage capacity, with water used inside the home and for fire fighting purposes. All black water and grey water is treated via a worm farm treatment system that treats the water for garden use.
Zen Architects did not just take the conventional approach to incorporating sustainability. “A key design element of the project was the use of recycled timber poles. These poles have had a long history — they were part of the old Geelong pier that was burnt down. The poles came complete with bar nacles, rusty nails and burn marks,” Zen says.
Old bolts from the pylons were handmade into door knobs. “When the poles were delivered, we went out and looked at them and the bolts were just hanging out of the posts. The client wanted them to look like a lever type handle but just made out of the old bolts,” Roy Kahle says.
“But they were a bit danger ous because you could get hooked on them so I came up with the idea of just using the ends that had the big hexago nal head on them, so you could grab them more as a knob rather than a bent over handle.”
Other products were also handmade. The plumber made brass backing plates into tapware by soldering them together and then screwing them on. When they were sil ver soldered the metal burnt, which gave the tapware an authentic old look and fit with the earthy feel of the home.
A large amount of timber was used in the project to ensure the house blended in with its bush environment. External cladding comprises radial sawn silvertop ash, which comes from the foothills of the Gippsland mountains. The stairs were also constructed using recycled sugar gum tim ber, with the core from the sil vertop ash used as handrails on the stairs.
The timber posts the house was built on included turpen tine and red ironbark, with the ironbark grown locally and even on the site.
It was the first time Kahle and Zen have worked togeth er. “Because the house was so organic and the client had such a large input to it, it was a really good relationship. They were really flexible and Ric was really knowledgeable in all the environmental issues,” he says.
“As far as the environmental perspective goes, we were able to achieve the goals that the client wanted as far as positioning the house, and having as little impact as possible on the site.”
Stephanie McDonald
