What exactly do we mean by 'sustainable,' 'affordable' and 'cost effective'? Warren McLaren ponders one of the great sustainability conundrums.
How do you construct a sustainable home which is affordable and cost-effective?
If ‘sustainable’ were taken to be ‘not burdening future generations’, then this raises the stakes high, for buildings kitted out with the likes of bamboo flooring, plant-based paints and recycled concrete bench-tops might qualify as ‘green’ or ‘eco’ dwellings. But that doesn’t mean they won’t, decades on, still be a drain on resource availability, for such buildings may be guzzling significant volumes of energy and water. That’s not to say careful consideration shouldn’t be given to materials selection, but they should not be seen as the end game, merely a bit player.
Environmental and social costs should also be considered alongside financial cost effectiveness. A cheap, uninsulated house requires more energy to heat and cool. With the bulk of Australian electricity (78 per cent) derived from coal-fired power plants, climate change is also an environmental cost of energy inefficient housing.
What is affordable to someone earning $300,000 will be rather different to someone getting by on $30,000. Technically, housing is considered ‘affordable’ when a low income household pays no more than 30 per cent of their gross income on housing costs (rent, mortgage, etc).
So how do we reconcile this triumvirate of competing demands?
A general rule of thumb is that at least 50 per cent of a new home’s cost is labour. If the home owner can contribute even some of the physical workload, it’s reasonable to assume the price of their home will be less. This is known as ‘sweat equity — the investment of personal time and energy, instead of cash.
Several styles of green building construction lend themselves to do-it- yourself involvement. Low cost, low embodied energy, high thermal mass mudbrick and highly insulative, structurally forgiving strawbales are suited to home owners with little prior building experience, though it should be noted that walls only comprise around 15 per cent of the total cost of home.
In most cases, a happy medium can be reached between reduced labour costs and a quality finish if the owner subcontracts an experienced tradesman. In this scenario the owner acts as the labourer, with the builder managing construction detail.
The American headquartered Habitat for Humanity (HFH), a faith-based home builder, has built over 350,000 houses in nearly 90 countries, including almost 2,600 energy star-rated homes in the US using the sweat equity model. Low income families contribute 500 hours of 'sweat equity' atop a low cost HFH mortgage loan. Although HFH Australia's focus is more on “simple, decent and affordable homes” rather than specific 'green' houses, there are exceptions. For example, the 20 or so grid-connected solar power homes being constructed in South Australia during 2009-10, with assistance from Adelaide's Solar Shop. For its first project in Western Australia, HFH worked with architect Kirsten Hay to design a passive solar house.
As a response to the 2009 Victoria bushfires, HFH also provided five 20 ft shipping containers extensively fitted out as Community Tool Libraries to help facilitate the rebuilding of devastated townships. Like its affiliates in the US and Canada, HFH Victoria operates a ReStore in Melbourne — a retail outlet which sells reused materials salvaged from the construction and demolition waste stream. This is another means by which the cost of house building can be both green and affordable.
Although, again, there’ll be a cost versus time equation that needs to be calculated. It takes more days to find appropriate reused materials than simply nicking down to the local building supply yard, and they’ll probably need more preparation.
Yet again, it is not solely materials that make a sustainable house, for the real cost of building a home is not in its build stage but in its operation.
The Council of Australian Governments (COAG) published its National Strategy on Energy Efficiency mid-2009, noting that Australia’s residential buildings account for around 10 per cent of the country’s greenhouse gas emissions. COAG proposes new mandatory disclosure provisions on the energy efficiency of buildings, effective from May 2011. It believes mandatory disclosure of a home’s energy performance at the time of sale or lease will give “industry greater confidence to innovate and develop affordable solutions to improve building energy efficiency,” suggesting that six, seven and eight star buildings “will become the norm in Australia, not the exception”.
Homes that rely on expensive, energy hogging air-conditioning and heating will likely have diminished resale value as the volume of more energy efficient houses entering the marketplace increases. Greening a home is therefore about to become a wise investment, not a financial burden.
But who said green or sustainable building had to be more expensive? The South Australian Department of Transport, Energy and Infrastructure didn’t. It believes “an energy efficient home is generally more comfortable, easier to maintain and costs no more to build than a conventional home”. It isn’t alone in this view.
A US study, The Costs and Benefits of Green Affordable Housing (2005), found that when averaged out, the so-called ‘green premium’ was just 2.42 per cent extra in total development costs. Additionally, it discovered that over the life of the dwelling, “… the benefits of green affordable housing are real and, in some cases, substantial. In virtually all the cases, energy and water utility costs are lower than their conventional counterparts.” Indeed, it determined that “decreased operating expenditures alone more than pay for the incremental initial investment in greening the project.”
An earlier study, Green Building Costs and Financial Benefits (2003), although more focused on US commercial and government buildings, arrived at the same conclusion — the average premium for green buildings was slightly less than 2 per cent. It further recognised that the “financial benefits of green design are … over 10 times the additional cost associated with building green.”
These and myriad other studies looked at not only the cost of home acquisition, but also operational expenses, a combination known as total cost of ownership. It’s a little discussed reality that has nevertheless bitten many a buyer, like shoppers enticed by an incredibly cheap bubble jet printer (acquisition), only to soon discover that the cost of replacement ink cartridges (operations) very soon outweighs the initial purchase. So it is with housing. Money saved on the building of a home may be quickly absorbed into the ongoing costs of heating, cooling, transport, etc.
Yet homes designed to rigorous sustainable standards, such as Europe’s Passivehaus, can achieve energy savings of 90 per cent compared to existing housing. Energy saved is money saved.
Affordable early design-stage solutions, like passive solar, still lag well behind our penchant for expensive ‘tack-on’ technological fixes like air- conditioning. As the aformentioned Green Building Costs study found, “generally, the earlier green building features are incorporated into the design process, the lower the cost.”
However, some technology has now, in fact, become cost effective. With current state and federal government incentives, it is very feasible for home owners to install grid-connected ‘active’ solar photovoltaic systems that pay for themselves in two to four years before becoming revenue generating assets.
Maybe one of the most significant impacts on housing sustainability and cost is also size. It is no coincidence that Australia has the world’s largest homes (as of 2009), and also the world’s largest per capita emitter of greenhouse gases. At 214.6 sqm, new Australian houses are now seven per cent bigger than those in the US, double the size of those in Europe and triple the size of those in the United Kingdom, according to Commsec, who commissioned the Australian Bureau of Statistics (ABS) to check the figures.
Bigger homes generally require more land, pushing them further away from infrastructure like shops, schools, public transport, etc. This in turn negatively impacts on household fuel and travel budgets. And more driving equals more carbon dioxide.
Smaller house solutions? Ditch the obsession with the double garage. Garages are largely a waste of time, energy, materials and dollars. Carports or shade sails do the job far more affordably than bricks and tiles.
Design homes that grow as family needs expand. Factor in walls, walkways and service access so additions can be easily added as required. Some kit and prefab housing designs manage this well, like the Fairweather Peake Series.
Promote the eco-benefits of medium density housing (so effective in Europe and the United Kingdom) that are appropriate in Australian context. Currently, almost 75 per cent of Australian homes are separate dwellings. Flats account for only around 14 per cent and terrace houses/ townhouses around 9 per cent of housing stock. And just think carefully. An L-shaped building can end up with 25 per cent more wall area than a square one of the same internal space.
The great ethic economist E.F. Schumacher wrote that small is beautiful. We neglect his advice at our environmental and hip pocket peril.
