While most people see eight acres of native bushland as an untapped entity to remain as such, Anderson Architecture see it as an opportunity. An opportunity to build a sustainable, self-sufficient, bushfire-proof dwelling in a research and development capacity. The result is Off Grid House, a grouping of passive and environmentally sustainable design principles that has seen Anderson Architecture Director Simon Anderson and his family’s energy use decrease exponentially.
The house has been built to a mantra of ‘a site’s chief problem should always be the source of its innovation’. Off Grid House’s main issue is it’s positioning. If the open-plan living space was to take advantage of the escarpments to the south, it would be oriented in a position that would effectively turn its back on the sun. Anderson decided to split the home into two steeply pitched volumes, oriented in opposite directions and serving completely different purposes.
The ‘box’ exposed to the most sunlight serves as the sleeping quarters, due to the passive thermal performance the volume receives throughout the day. The ‘living’ box, despite a lack of sunlight, contains a 6.7kw solar system installed on its roof for power generation. Double glazing, under-floor heating and increased insulation ensures the heat of a wood fire brings enough additional heat through the winter, with wood sourced from the site and its surrounds. A heat recovery system ducts warm, fresh air heated by the stale exhaust air, to the sleeping and living zones as needed, too.
Taking cues from the escarpment, the living area is deeply inspired by the surrounding landscape. The grey weathered outer faces and luminescent sandstone undercrofts of the natural landform are echoed with the implementation of glass doors that slide away on two faces of this room, creating a similarly cave-like cantilever and blurring the indoor/outdoor boundary with the sunlit deck beyond.
Living in such dense bushland requires critical thinking in regards to potential issues, such as termites and bushfires. Anderson opted for a fireproof concrete structure, alleviating any stress surrounding both problems.
Low-carbon fibre cement board cladding and decking gives the illusion of a timber finish, while being able to withstand a high bushfire attack at the BAL40 level. The practice designed a bespoke 2.4m external metal screen, that can be winched out of sight, that protects the interior from the rain, or as a defence mechanism against flames in the event of a fire, with motorised screens also implemented on other windows. When heavy rain hits the home, both roofs run off to feed water tanks with a capacity for 30,000L. Long term, the tanks will be moved under the deck to offset overflow and account for stretches of drought.
Being an off the grid, a range of sustainable features have been administered to ensure the house remains self-sufficient. The house amounted to net zero CO2 emissions in the building process, and runs at net zero CO2 emissions as well. The 6.8kw solar PV system is accompanied by a 27.6 kwh battery, with a worm farm taking care of sewage. The decking and cladding is low carbon magnesium oxide board, made from 60% post consumer recycled content. A heat pump system is used to warm the house, with Black Oxide insulated concrete floor providing thermal mass.
Fast becoming experts in off grid house design, Anderson Architects have worked through the adversities of isolation, bushfire and orientation to create a home that is completely passive. Contemporary in styling and innovative in amenity, the home is the cabin in the woods of the future, that brings no harm to the world around it, or anywhere for that matter.
