Garden cities of tomorrow - Page 2
From Griffith REVIEW Edition 29: Prosper or Perish
© Copyright Griffith University & the author.
Written by Tone Wheeler
AS DENSITIES INCREASE, blocks of land get smaller; houses get closer, sprout two or three storeys and become so tight that the sun doesn’t reach the ground. Turning the house upside down, with the bedrooms and home offices on the lower floors and the living areas on the upper levels and roof, will give greater access to sun and breezes. It sounds Mediterranean, and there is a salient lesson: the Greek or Arabic home, with a flat and habitable roof, may be a better climatic model for Australian cities.
The current environmentally sustainable trend is for a green roof, designed for both green planting and green technology. These can be used as living areas, to grow food and sequester carbon, as well as for solar thermal and electricity generation. But the idea of barbecues on the roof, outdoor plasma screens and sleepouts looking at the stars (through clearer air) is challenging for many councils, who see only the downsides – loss of privacy, overlooking neighbours, and amenity problems – rather than the environmental benefits that a better-performing house might offer.
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. The predilection for brick as a veneer over a timber frame is the opposite of what is needed: the internal house is lightweight and does not store warmth or coolness, while the mass of external brickwork adds little by way of insulation. The brick blocks, in situ or precast concrete, should be on the inside, wrapped in a layer of effective insulation with a weatherproof veneer on the outside.
Often in higher-density housing this happens by default; solid party walls and concrete upper-level floors offer 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, offer little acoustic privacy or good land use; but they are cheap. A single party wall takes up less space, yet costs more, as it has to reach a higher standard of fire safety and acoustics – and so a smaller townhouse, on less land, becomes more expensive.
The thermal comfort of apartments is improved by exposing the building’s concrete ceilings. With the need for apartment floors to be insulated against noise transfer, the exposed mass is often found in the walls and ceilings, which keeps them cool. We are 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 in ceilings, absorbs the day’s heat, which can then be night-purged using colder night-time air, making the house cool for the next day. As electric-powered cooling produces more greenhouse gas than heating, general uptake of this kind of passive cooling would substantially reduce carbon 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, and at the same time support heavier upper floors.
Finally, turn it back to front. The car’s influence on house design has grown disproportionately; the garage is now the largest and most prominent room in most project homes. Many councils have legislated a set-back from the house alignment for the garage, and limited its dimensions to no more than half of the frontage. As garages get bigger to accommodate SUVs and 4WDs, and the houses get closer, the large steel garage door dominates many streetscapes – a last gasp image of the twentieth century’s love affair with cars.
In the new century the car is best banished to the rear, to a service lane: we go back to the future of the nineteenth century. This will be aided by the imminent demise of the big car, for soon we will see the uptake of smaller options: smart cars, mini electric cars, electric bikes and so on. The traditional garage size will be seen as excessive. A rear service street will be narrow but accommodate smaller cars, mini recycling trucks (there will be less garbage, with less packaging and consumption, and more composting on the green roof) and a safer area for children’s play. And over the top of the garage could be a Fonzie flat, a second residence for the third generation, a nanny, a guest, student or bon vivant to bring you ‘happy days’.
Townhouses and apartments will face a public street, possibly lined with small businesses in the ground-floor home offices, or new shop-houses, the greater density enabling the revival of the pedestrian– and cycle-friendly street. Smaller vehicles mean more and better car parking between the trees that form a shade canopy for the entire street.
THE UPSIDE-DOWN, inside-out, back-to-front townhouse will increase the number of residents threefold, but another typology will be needed to get to the desired sixfold increase. And three-storey redbrick walk-up flats may be the surprise package – the most reviled house form in Australia could be the most sustainable. They have a small footprint, modest-sized apartments, high thermal mass, minimal parking. With a bit of tweaking they could be ideal. The external brickwork can be wrapped in rigid external insulation and cladding (with muted colours), to increase the thermal mass and reduce the redbrick overkill. Balconies could be extended and fitted with better balustrades, screens and planting for privacy, together with shading devices over exposed windows. This will increase the amenity and the thermal efficiency of the building, and rebuilding the garden will offer the potential for productive food gardens as well as better landscape screening. We could go further and remove the tiled roof and replace it with a flat green roof.
The economic imperative to make these changes has not yet arrived, but the qualities of this design are incorporated into hundreds of infill projects already being built. There is a perception, fostered by groups such as Save Our Suburbs, that these developments been foisted upon an unwilling and resistant public. Activists from wealthy suburbs often regard these apartments as a sort of socialist conspiracy, but they are actually a perfect example of the market economy in action. With the exception of some recent government-sponsored affordable housing, apartments are built by developers, who are driven by profit. The traditional formula for success is to split the sale price into thirds: land, construction, profit. The project won’t stack up unless there is demand, and at a relatively high increase in value. Sadly for SOS, the secret to the success of these apartments, and the continued demand for their construction, is the enemy within: local residents, downsizing from large houses when children leave home, are buying into a different way of living in the suburbs they know and love.
Many of these low-rise apartments are based on passive thermal design, using solar gain to provide warmth in winter, and cross-ventilation and night-purging in summer. This has been a feature of well-designed freestanding houses in temperate Australia since the publication of Homes in the Sun by Walter Bunning, in 1945. What is unique is the attempt to transfer these ideas into medium– and even high-rise buildings.
DWELLINGS IN EUROPE and North America have larger heating, ventilation and air-conditioning systems, in buildings that are far more tightly sealed and permit much less interaction with the surrounding climate. This is due not only to harsher, colder climates, but to the prevalence of higher-density dwellings that demand greater privacy and hence fewer windows, openings and external spaces.
Urban consolidation and the higher levels of thermal comfort are pushing Australians to more sealed dwellings with less passive design. We could develop buildings like Solaire in New York, a LEED-certified housing tower by the US architect César Pelli that has walls embedded with solar photovoltaic panels (to make electricity) embedded in the façade to offset the energy demand; or press on with naturally ventilated apartments, with single-depth plans and deep blade walls for privacy, such as those by the Australian architects Frank Stanisic and Ian Moore. The latter’s Altair was highly awarded internationally and suggests that, while there is local pressure to follow the European and North American example, many temperate areas in South America and Africa want to follow Australia’s lead.
Many architects are preoccupied with finding the most sustainable type of residential dwellings. At one end is suburbia; at the other, high-rise towers. The towers are certainly dense, but often perform poorly in energy and water use – foyers need lights around the clock, car parks need mechanical ventilation and apartments are usually fully air conditioned, and there is little roof for water collection and use.
WHERE ON THE bell curve sits the most suitable mix of housing density, transport proximity and urban form? It may well be that between forty and fifty dwellings per hectare is the answer – which is about five times suburbia but only a fifth of high-rise. With the change in form comes a change in the design of streets. Ideas of a more cosmopolitan city that were championed in the 1960s come back into focus, such as Edward Cullen’s Townscape (1961) and Bernard Rudofsky’s Streets for People (1969; tellingly subtitled ‘A Primer for Americans’). Often the new housing forms go hand in hand with public transport systems: so-called transport-oriented designs.
In Sydney, this is linked to the evolution of the cities-within-cities approach championed by Sue Holliday, president of the Planning Institute, and developed by the former state architect Chris Johnson in the regional plan to strengthen existing urban growth centres such as Parramatta, Penrith, Chatswood and Liverpool as cities in their own right, with medium– and high-rise apartments within easy walking distance of their centre.
A different form is proposed by the Melbourne City architect Rob Adams, who has suggested that far greater density can be achieved along the high streets of that radially formed city. He mounts a persuasive argument that streets, as well as buildings, are the key to future urban design and suggests that only 6 per cent of the city fabric will need to be changed to three– to five-storey townhouses and apartments over shops and offices along tram and train lines, leaving most suburbs untouched. Density can be increased to maximise the efficient use of services, without the need for wholesale changes to the house form that Australians are so fond of.
In Perth, Peter Newman has developed the radial transport-orientated design even further, with a freeway and integrated train line from the city centre to Mandurah offering the chance for hubs at every station, although so far there are only commuter car parks. This green-field planned approach is far easier to implement than the kind of reworking of the existing fabric that Rob Adams proposes. Resistance to linear transport-orientated design can be seen on the North Shore of Sydney, where Ku-Ring-Gai Council is at odds with the state government’s mandate of urban consolidation along the existing highway and railway lines.
Peter Skinner at the University of Queensland proposes a different form of development for South East Queensland: a dense, linear city that hugs the coast, which is the main lifestyle drawcard, and stretches from Noosa to Coolangatta. Focusing on low– and high-rise residential buildings, it would release the hinterland from the current pressures for rolling green-field suburbia and allow it to retain its role as environment lungs for flora and fauna diversity, water collection and recreation. If you are going to destroy the most desirable coastal land, you should maximise the return for as many people as possible.
The question of how Australia will accommodate an extra fourteen million people by 2050 pales by comparison with the global challenge of housing nine billion people by the same year. The building industry is currently the largest employer in the country, and it is driven not only by new dwellings but by perpetual renovation and maintenance. Looking to the future means making tough and innovative decisions about how to construct more diverse housing that is sustainable and sensitive to local traditions – and that may just mean turning them inside out, upside down and back to front. ♦