The Future Green House

Feb 25, 2010
  • Article by Tone Wheeler
  • Designer

Looking at anthologies of 1970s solar houses (and there are almost as many as there were houses called ‘Solar 1’) shows they had one unusual thing common, apart from large areas of glass facing north: space. Not inside, for they were relatively modest as befits their era, but outside. In order to face the sun (copying the North American and European models) they had large areas of garden to ensure solar access. Great play was made of the need to face north, not slavishly facing the street, and without the presence of evergreen trees or adjacent houses that might block the sun.

That fascination with the independent house (autonomy was the Holy Grail) continues today. The same simple rules (insulation, glazing, orientation, thermal mass and ventilation) apply in demonstration houses now called ‘Living Green 1’ or ‘ESD 1’. However, there is another layer to sustainable design that runs counter to the freestanding home: the need for residential density, that brings environmental benefits with economies of scale in infrastructure, services and particularly transport.

What happens when you squash lots of green, passive solar homes together? They don’t work; they overshadow each other, the cars dominate the streetscape and the houses can’t breathe and cross-ventilate. But why can’t we have both? Some combination of socially efficient higher density housing that still retains the best aspects of the freestanding home – individuality, privacy, variety and access to the garden? This is the new Holy Grail.

The solution lies in a de Bono leap – it requires us to think outside the box. The future green house may well be one that is upside-down, inside-out and back-to-front.

To counter the effects of overshadowing in medium density it can be beneficial to turn the house upside-down. As densities increase, the blocks of land get smaller, the houses get closer, become two or three storeys and are so tight that the sun doesn’t reach the lower floor. With the house turned upside-down, bedrooms and home offices are on the lower floors and the living areas are on the upper levels and roof. And if you’re thinking that sounds Mediterranean you’re right, and therein lies a salient lesson: many of those early solar houses were besotted with innovative overseas designs, without noticing that they had been developed in inappropriate, colder climates. Australia’s biggest six cities are far more temperate, and the Greek or Arabic home, with a flat habitable roof, may be a better climatic paradigm to draw from.

This begs the question of the latest ESD trend: the ‘green roof’. Not to be confused with a common or garden roof, these are designed to have both green planting and green technology. Being accessible, they can be used as living areas, to grow food, sequester carbon, as well as for solar thermal and electricity generation. But the idea of BBQs on the roof, outdoor plasmas and sleep-outs looking at the stars (through clearer air) is a challenging concept for many councils, who see only the downsides – loss of privacy, overlooking and neighbour amenity problems rather than the environmental benefits that a better performing house might offer.

Regardless, this approach may well stumble for more practical reasons: access from a basement car park to a kitchen and living areas several floors above may demand a dumb waiter or lift (undoing the energy gains) and perhaps we are not yet ready to think of turning our living patterns upside down.

The second challenge is to turn the house inside out: recent research suggests that thermal mass has been underplayed in the design of houses for temperate Australia. Our predilection for brick as a veneer over a timber frame is the exact opposite of what is needed: the internal house is lightweight and has no storage of coolth or warmth, while the mass of external brickwork adds only a little by way of insulation. We should have put the mass (concrete blocks, precast, bricks etc) on the inside, with a layer of more effective insulation around it, and then a more weatherproof veneer on the outside.

Often in higher density town housing this increased mass happens by default, with solid party walls and concrete upper level floors offering better mass and acoustic isolation. By contrast the boundary walls of freestanding homes, facing across a two metre ‘demilitarised zone’ of water heaters and fences, offers little by way of acoustic privacy or good land use, but it is cheap. To build a single party wall, which takes up less space, costs more as it has to reach a higher standard of fire safety and acoustics, and so, curiously, a smaller townhouse, on less land, becomes less affordable.

One thermal comfort upside of apartment construction is the increased use of concrete. With the need for apartment floors to be insulated against noise transfer, the exposed mass is often found in the walls and ceilings, and this has the great benefit of promoting coolth. We are well used to the notion of passive warmth being facilitated by sun shining on the floor. The converse is true in summer: thermal mass in walls and particularly ceilings absorbs the day’s heat, which can then be ‘night purged’ using colder night-time air, rendering the house cool for the next day. Given that electric-powered cooling produces more greenhouse gas than gas heating, a more general uptake of this kind of passive cooling approach would have a substantial impact on emissions.

A symbiotic relationship between the first two ideas now emerges – the upside-down house needs concrete for the upper living floors, and to support the green roof, and so this immediately offers the potential to build it inside-out, with mass to support these weightier upper floors.

Finally, why turn it back to front? Well, it’s the effect of the car, that’s influence over house design has grown disproportionately in the last 50 years, to the point where the garage is now the largest and most prominent room in most project homes. So much so, many councils have legislated a set back from the house alignment for the garage and limited its dimensions to no more than, say, 50% of the frontage. As the garages get ever bigger to accommodate SUVs, wagons and 4WDs, and the houses get closer on smaller sites, the large steel door, occupying more and more of the streetscape, is a last gasp image of the 20th century’s love affair with cars.

So for the 21st century the car is best banished to the rear, to a service lane that is a ‘back to the future’ return to the 19th century. This will certainly be aided by the imminent demise of the big car; soon we will see the uptake of a whole host of smaller personal mobility options: smart cars, mini electric cars, electric bikes, cycles and so on. The traditional garage will be overkill. The rear service street will be narrow, but will accommodate smaller cars, mini recycling trucks (because there is less garbage, with less packaging and consumption, and more composting on site for the green roof) and a safer area for children’s play.

Townhouses and apartments will face a public street, possibly lined with small businesses in the ground floor home offices, or new ‘shophouses’, the greater density enabling the revival of the pedestrian and cycle friendly street. Smaller vehicles mean more and better carparking between the trees that form a shade canopy for the entire street.

The battle to design a freestanding sustainable home has been won, but it is a pyrrhic victory: it is now seen as a worthy object, that’s dependence on a massive infrastructure and hidden transport costs hinders rather than aids the development of a sustainable city. The push is on to increase residential density, but we are in danger of throwing out the baby with the grey water in a rush to medium and high-rise apartments. A century of freestanding homes has bred a love affair with the possibilities of an indoor and outdoor private life, a lifestyle that will not be easily shoehorned into towers.

Three typologies from the past may indicate a way forward. Terrace houses, with their party walls and rear lanes, could be updated with green roofs. Courtyard homes offer privacy with compactness. But the reviled three storey walk up may be the best surprise package – it comes with high thermal mass, which can be wrapped in cladding and insulation to reduce the red brick overkill, balconies can be extended and fitted with planting for privacy, and a new green roof can be built over the brick walls.

Conversation • 4 comments

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28 Feb 10 at 11:13 PM • Coll Callander

Simple mechanical logic applied to dumbwaiter and lifting systems based on pulley and fulcrum could be developed to obviate the need for electrically operated lifts.

16 Mar 10 at 2:24 AM • Brendan Meney

Our obsession with the technical fix has become disproportionate to simple design solutions.
This article is full of sensible, practical, innovative thinking – we can only hope there is more uptake!
Sit on the roof top of an Arabic tower house with a 1000 year old proven design history and you will know what Tone is talking about.

04 Feb 13 at 1:07 PM • ANNEKE

I love your thinking! I’ve been imagining a house i’d love to build on a suburban sydney block, and the one thing i keep picturing is a flat roof for a garden/ breezy outdoor space. like a mediterranean style villa. unfortunately those house design companies i’ve contacted have cited privacy concerns for neighbours / planning restrictions that it couldn’t be done!?! Exactly as you say. Heartbreaking really…when you look around the burbs at what is being built…carbon copy mausoleums… *cries*

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