Adhami Pender Architecture

“We are going to leave this house in a box and we are not spending any money on heating or cooling!” This was the message that came through loud, clear and non-negotiable when the owners delivered their brief. All other matters were flexible but the primary design criterion was that this was to be a house that certainly fulfilled Corbusier’s dictum of being “a machine for living in” but, more crucially, that “machine” was to be one to absorb and retain the heat, or cool as required for Canberra’s large diurnal and seasonal fluctuations.

The house has been open several times on Sustainable House Day, and each time has excited great public interest because of the spectacular internal spaces that are integral to the design. The house is a joy to live in, and exceeds expectations since we came from living in “a fridge in winter and an oven in summer”.

T + S Woodburn

The dynamic sundial-like building form that evolved follows the sun path of the winter solstice, maximising the sun penetration in the winter and minimising it during the summer: a “machine” for sun capture. The aesthetic that emerged would be one that derived from the physics of solar and thermal science, not one that mimicked current building or town planning fashion. It was to be strong, brave and proud of its primary generator: a house that worked!

The house is passive solar. Energy charges are constant each quarter: there are no major changes associated with the seasons. A feature of the design is that there is sun penetration into every room in the house for at least part of a winter’s day, with the living areas receiving maximal sun.

The exterior landscaping is integral to the design of the house. Paving by the north glass wall has been kept to a minimum. Instead native grasses, daisies, and bluebells have been planted to minimise reflected heat entering the building. The paved outdoor living area is sited so that there is no heat reflected into the house. The ornamental grape vines over the ‘deciduous’ eaves are also essential to the design, allowing maximum sun penetration in the winter, and minimal penetration in the summer.

The building has an extensive insulation envelope, including the footings and buried “skirt” insulation external to the house. This isolates the slab and the sub-base of the envelope from the extremes of summer and winter, thus increasing the benefit of the constant geothermal energy input. Treated grey water is piped into the house to flush toilets. Collected rain water is used for the garden. Recycled timber and doors were used where practical. Trombe walls add to the thermal mass capacity, and no penetration of the ceiling cavity by down lights maintains the insulation integrity. R5.5 insulation to the ceiling and 50mm rigid high density foam is laid between the cavity brick walls. Thermally bridged double glazed windows, with 900mm opening, utilise diurnal temperature variation to cool the envelope.