Over a building’s life, greener is also cheaper
IN the construction industry, the accepted wisdom is that eco-friendly translates as hip-pocket hostile.
Perth-based engineer Richard Haynes disagrees. Last month, he launched eTool – web-based software that figures out the full greenhouse impact of your new home or renovation.
Both he and his collaborator, Alex Bruce, were surprised by the results when they tallied the long-term costs and impacts of different building materials.
“The most interesting thing we’ve discovered using eTool is that there’s a good relationship between sustainability and prices. Now, even if I was making purely economic decisions, I’d choose many things that are very sustainable, just to save on the costs,” he says.
The reason green products are often cheaper over their life cycle, Mr Haynes says, is because of the higher replacement and maintenance expenses of many conventional products. But those costs normally remain hidden.
Internal fittings and finishes, such as floor coverings, paint and plaster can eat up a hefty portion of a home’s carbon pie, over its lifetime. “When you build, the embodied energy of the carpet might only be five per cent of the carbon emissions, but if you re-carpet every ten or fifteen years, it becomes significant – and in a cost sense as well,” he says.
Similarly, a low-embodied energy rammed-earth wall that doesn’t need painting could prove cheaper than double-brick and plaster, even if it costs more to begin with.
The eTool software is free for householders. It uses life cycle assessment to provide an estimate of the building’s carbon footprint and its likely costs, both upfront and ongoing.
It takes into account the energy that goes into manufacturing the materials, as well as transportation, assembly and maintenance. The program also considers the energy required to run the home once construction is complete, by combining the building’s star rating with extra factors, including the lighting, hot water and heating systems, and the number of occupants.
“We’re engineers, so we’re all about quantifying,” Mr Haynes says. “But our motto is to be vaguely right, not precisely wrong. Any life cycle assessment could be out by a third, due to the differences in the way people operate the same house.”
Based on his research for eTool, however, he has clear advice for anyone considering a building project.
“The best thing you can do is to increase the design life of the home,” he says. “It’s an unfortunate reality in Australia that the vast majority of buildings get demolished for fashion or economic reasons, rather than the building envelope wearing out.”
So how can you prolong your home’s longevity?
Mr Haynes suggests investing in top-notch design, opting for higher density, or renovating instead of rebuilding.
“Better design means the home has a more timeless quality. It will be appealing well into the future,” he says. “And if you can surpass the average density for your suburb then it’s likely your building will be a lower priority for redevelopment.”
Renovating extends the lifespan of the existing home, but for long-term energy savings, you have to do it with passive solar design and energy efficiency measures in mind.
“By preserving the structure, you’re preserving that embodied energy,” Mr Haynes says. “You can make an enormous difference to the aesthetic value and liveability of your house by renovating.”
Great article