Karool House

Straw. It has covered the roofs of mediaeval cottages and quintessential Dutch windmills. Livestock eat it. Van Gogh painted stacks of it. One of the three little pigs chose it as a building material, albeit with disappointing results. It certainly doesn’t come to mind as the building material of the future. But for this home, nestled in the hills near Michelago in the Australian Capital Territory, straw is the key to ecosuccess, or at least one of them. Hugh Gordon’s ‘Karool’ is an impressive glimpse back to the future, where technology gets back to basics, and eco is everything.

The clients for this project - also the owners and full-time residents - are passionate advocates of sustainable design, so they desired a home that embodied environmental sustainability while also being extremely liveable for their young family. Situated halfway down a shallow, natural amphitheatre, the site is neither too exposed like a hilltop, nor too shaded as a valley floor might be. This position also gives the home its unique curved form: an arc in the true mathematical sense of the word, a bar-like section of a circle’s circumference, hugging the hill along its rear southern side, and facing out towards true north into the valley space.

The southern aspect is formed by a high, 500m-thick straw bale wall that runs along the curve of the hillside, so while it never sees direct sunlight, it serves as an insulating mass for the exposed sides of the house. This wall is punctuated by deep-silled picture windows framed in recycled Ash, which has significantly less heat transfer properties when compared to the usual choice of aluminium framing.

The open face of the house features double-glazed windows to capitalise on rustic vistas, opening onto a wide, north-facing terrace, with a deciduous vine covered pergola for shading in the summer months. An interior hallway runs like a curving spine along the length of the home, with the main living area at the midpoint of the arc, the parent’s and guest retreat to the east, and the children’s room and laundry to the west. The external east and west end walls are reverse brick veneer–with the brick on the inside to increase thermal mass where it is most useful–and clad in horizontal corrugated iron, like quotations borrowed from the traditional Australian rural vernacular.

Recycled Tallow-wood frames–an old bridge in a former life–make up the actual skeleton of the home. This timber is harder and tougher than new wood, and therefore more difficult for builders to work with, but it is also more settled, predictable and fire resistant–a ‘must’ for any rural property. Inside, the compacted straw remains uncovered on the ceilings, with unobtrusive fans to facilitate the natural airflow. The rear wall is lightly finished with the same deep red limewash that appears on the exterior, giving the home a rustic Wild West Californian ambience. The other internal walls are of rendered masonry, and the flooring throughout is burnished concrete for maximum thermal mass, allowing for the dissipation of excess heat directly into the earth.

The owners and architect both accepted that the building of Karool would be more expensive in the short term, but would lead to immense savings in the long term. No power bills, for one. No water rates either. The home is entirely off-grid. Some distance away from the main structure is a free-standing shed, which houses all of the photovoltaic panels and batteries needed for the family’s power supply. Rainwater collected from the roof of this shed supplements that which is gathered from the barely sloping roof of the house, and directed into a large concrete storage tank below the site.Water from this tank is periodically pumped to a smaller, higher tank, and then reticulated by gravity back to the house, providing all the fresh water used in the home and for watering the native garden. Perhaps the bravest step towards ec-osustainability is the composting toilet, which recycles grey water from throughout the home to dramatically reduce fresh water consumption in what is typically a very water-greedy room.

Energy consumption is further reduced by the family’s carefully planned choice of home appliances. There is an outdoor wood-fired pizza oven for one, and of course, a solar hot water heater. Additional room heating, when necessary, comes from a centrally-located and highly efficient slow combustion wood heater. A root cellar–named for the American method of storing winter root vegetables–is in the form of a 2-metre diameter concrete pipe dug into the hill behind the house. Most of the family’s fresh food is stored in this naturally cool room, so that the internal kitchen fridge is only a fraction of the usual size (and cost).

Until recently, Karool might have sounded like a Luddite’s paradise, a hermit’s retreat: the house that modernity forgot. A decade ago one would have thought that a house made primarily of compacted straw and recycled timber–a house totally isolated from mains water and power grid–would be completely at odds with modern trends and technology. But times have changed, and now Karool is the pure embodiment of cutting-edge, eco-conscious architecture and living. +