Green homes cheaper to run and build, so reach for the stars
- Date
When the CSIRO began the biggest study of energy performance of Australian houses, one resident bemoaned the woeful output of his home’s photovoltaic panels only to be told the unit was actually a solar hot water system.
Researchers found other surprises among the 414 households studied.
Almost three-quarters of homes in Melbourne and two-thirds in Adelaide believed they had efficient lighting but the study found 81 per cent in both cities used power-sapping halogen lamps instead. And 28 per cent of Melbourne households said they had double-glazed windows – twice the actual rate.
Perhaps the biggest surprise, though, was a finding that houses with higher energy ratings actually cost less to build than poorer performing ones.
”We’ve known for a long time that more efficient houses cost less to run,” said Glenn Platt, who heads the CSIRO’s energy efficiency unit. ”What we’ve seen in this report is that they’re cheaper to build and to run, and that’s fantastic news.”
The study - The Evaluation of the 5-Star Energy Efficiency Standard for Residential Buildings – examined houses built in the past decade and was released without fanfare last month by the federal industry ministry.
It found that building a five-star rating rather than four stars saved about $7500 in Brisbane, $5700 in Adelaide, and $5000 in Melbourne. Although restricted to the three cities – Sydney is under a different ratings system – the findings are applicable across the country, Dr Platt said.
Greenhouse gas emissions were also 7 per cent lower for the five-star or higher houses.
Phil Harrington from pitt&sherry, an energy consultancy, said the CSIRO study was the latest to show an extra star could be achieved at ”no cost, or even a negative cost”.
”It’s just that we do have a building industry in denial at the moment.”
Mr Harrington is finalising a study funded by federal and state governments examining why energy efficiency – both new builds and renovations – often falls short of the construction code.
However, Kristin Brookfield, a senior executive director of the HIA, said the report showed ”energy efficiency is still a very mixed bag, both in terms of costs and performance”.
There was limited consistency in how houses performed, Ms Brookfield said, noting that while higher-rated houses used about 50 per cent less gas in Melbourne in winter than lower-rated ones, they didn’t perform as well in Brisbane in summer.
Construction costs were lower for the more efficient houses, in part because they tended to be more rectangular in shape, something that may not appeal to many consumers, Ms Brookfield said.
Having less window area and more walls, particularly on a home’s western side, also helped save costs and cut summer power bills for cooling, the CSIRO found.
One intriguing query posed was why many of the houses fell short of the energy rating they were supposed to meet based on their year of construction.
Homes built since 2006 in Australia were required to meet a five-star standard, raised to six stars in 2010, as measured by software accredited under the Nationwide House Energy Rating Scheme (NatHERS).
Alan Pears, an adjunct professor at RMIT who helped design and implement Australia’s first building energy ratings in Victoria 23 years ago, blames poor compliance for the ratings shortfall.
”A lack of enforcement of building energy regulations by state and local governments has undermined compliance with them,” Professor Pears said, adding that gaps in insulation and air leaks left by builders often undermined energy performance.
”Once a few builders have been required to ‘make good’ their own non-compliant work at their own cost, we may see some improvement across the industry,” he said.
The government said it was considering the CSIRO’s report.
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