When Marr Grounds retired from University of Sydney Faculty of Architecture to the South Coast in the 1980s he was determined to put into practice the principles of ecological sustainability that had been the basis of his teaching practice. For the first few years following his southern migration he looked after Penders, the property bequeathed to the National Parks by his father Roy Grounds and Ken Myer at Bithry Inlet, on Lake Wapengo, near Tanja. From its once exploited condition as clapped-out rural scrubland, after some forty years the Grounds/Myer estate is now a model restoration of a natural environment, and is also the location of two significant Roy Grounds buildings, both constructed out of an early application of treated timber logs.

During his years as custodian of his family’s half of Penders, Marr planned his own response to the challenge of living in this south coast environment. With the family’s period of tenure drawing to a close, he bought the adjoining block of regrowth Spotted Gum forest, and set about planning and building a new residence, to be named Narra Bukulla. We’ve previously written about the sculptural characteristics of the modifications Marr made to the topography, and the multiple objects and structures he has created in the surrounding precincts. Here we want to talk about the house.

Building the house was to Marr what a thesis is to an academic: it’s a way of experimenting with ideas and principles, and testing the validity of an approach to a living space which is sustainable and independent, yet as a model for future low-cost housing projects. These were the ideas he shared with his architect, Tone Wheeler, who had once been one of Marr’s students. Today we want to look at the five-year old building, and see how it stands up to sustained usage.

Of course Marr Grounds accepts that some aspects are anomalous – the seven bedroom dual occupancy dwelling with enough permaculture garden and supporting infrastructure to support a crowd of residents went approximately 300% over budget (about half of which was outdoors), and yes, it is a lot for one man and his dog. Sometimes he says he prefers the studio workshop shed he started out with and on several occasions he’s built extra sheds, which in the future could become testing grounds of alternative forms of accommodation.

The principles are straightforward: a linear east-west house, roof angles calculated to maximise heat and solar energy entrapment, elements separated by breezeways, materials based on modular industrial materials and low-cost fitting which require minimum maintenance, rich soil created on shale by proven permaculture methods, plentiful water trapment and storage, effluent containment, and a bushfire sprinkler system for when it happens. It looks great. It feels great. It has a great spatial character as you move from indoors to outdoors, from living space to garden space, from garden to bush and back again.

The formal geometry of the building, and the articulation of materials and spaces are precise and harmonious, within a guiding principle of economy and low-maintenance: the self-supporting Ritek roofing structure (insulation sandwiched by corrugated iron inside and out – and it was a fight to get Council permission to retain the metallic finish) meets the austere fibro-cement modular walls precisely and economically. On the north face the whole structure is unified by its massive longitudinal wooden trusses which hang off the freestanding Greybox corner poles. The pole theme is an echo of both the surrounding forest and the sculptural installations we’ve spoken of earlier.

Marr worries about the longevity of these materials – what will happen to such foamcore structures over time – and how they would stand up to a firestorm? They’re “fire-retardant” but would they retain their structural integrity after being exposed to intense heat, he asks. Longevity is also an issue with solar systems – the original independent battery system proved uneconomic, and was soon abandoned for a simpler connection/contribution to the grid. Likewise, one of the solar hot water systems failed just outside the warranty period, and the Enviroloo composting toilets never worked properly. Even with the intervention of heating panels and enhanced chimneys, the loos were smelly and dysfunctional, and the periodic cleaning process was disgusting. Marr now realises that by locating them on the cold side of the house, buried rather than exposed, the elements of this southern climate were against them from the start. They are now, he says, the world’s most expensive planter boxes…

Why do such things happen, when logic, rationality and economy determine aesthetics? This is Howard Liddell’s ecominimalist critique in full effect. In principle, in retrospect, to embody the full suite of original features was an ideological rather than a pragmatic motivation. This is what makes it a thesis of a building, and Marr continues to be its own best examiner.

So we asked him what else would he now do differently? Not much, it turns out. Passive heat control required some fine tuning. The trusses needed infill insulation to prevent over-heating in winter, and there’s twice too much glass area which leads to too much heat loss on winter nights. He now sees how half the number of double glazed wooden frame windows would have stabilised the interior temperatures without diminishing the aesthetic pleasures of the marvellous views, or the sense of the flow of light and space.

What aspect do we like best? We like the quality of light, the flow of space from inside to outside, the integration of vegetable cages and gardens as living rooms in their own right, and the long perspectives marked by the quirky presence of the non-sculptures… So it’s ageing well, and living up to its award-winning recognition. Bravo!