Australian off-grid home design

Its not quite a McMansion, as its appearance is too distinctive, but is this $500,000 home a case of greenwash, or just naive?

An Australian design company has won a local eco-building award for its huge Convertible House, which looks like an upmarket Nissen hut, with a curved, corrugated iron exterior; the wrinkly tin is ubiquitous in Australia — think water tanks and sheds.
Perched on hilltops, the off-grid home has a balcony extending around the front and sides, allowing the owners to take full advantage of their surrounds. The design brief was extensive — to create an alternative, environmentally sustainable, durable, semi-prefabricated, low embodied energy, highly secure and fire-resistant family home.
The three-bedroom property by Designology won best energy efficiency at the Victoria State Building Designers Association (BDAV) Awards.
The company created the original design five years ago, having aimed “to come up with a better way of building — a way that tackles climate change” and that could withstand extreme climate as well as bushfires. But did it need to be quite so large?
The building is ugly and battled visually with hits surroundings – and it is unnecessarily big – which increases its carbon footprint as well as maintenance and building costs.
Upstairs measures 140 square metres and incoudes the living room, kitchen, bathroom and two bedrooms, while the ground floor has an office, guest bedroom, bathroom and rumpus room. Orientation was key to the design and all windows and sliding doors face north in all the communal rooms. The heat entering through these windows in the colder months is absorbed by the compressed cement sheet floors. In combination with the floor and wall insulation, this heat is stored and re-radiated into the building. The
A solar conservatory over the stairwell and entry area acts as a heat bank during the day in winter by maximising solar gain — warm air is trapped, filtered and redistributed to other rooms using heat recovery ventilation. In summer, this acts as a thermal chimney, drawing in cooler air from vents on the lower level and expelling it through vents at both ends of the building. This thermo-suction effect is also employed in other areas of the house. South-facing roof windows open to allow cross-flow ventilation in the main living areas.
Building materials were chosen for their durability, recycling potential, aesthetics, ease of transportation (ideally locally sourced) and overall cost effectiveness. The steel Colorbond roof and wall cladding, for example, has been specified for these inherent properties, as well as being low maintenance, fire and storm resistant and low cost; it is also ideal for rain harvesting.
Designer/builder Designology Pty Ltd