Retrofitting older homes
in Greener Homes on 11 July 2010
Older homes have the potential for energy efficiency on the cheap.
NEW houses must comply with six star energy regulations from next May. But what about our existing homes – how do they rate and how can we best improve them?
The Moreland Energy Foundation and Sustainability Victoria recently studied the energy performance of a group of older homes. “The vast majority of houses are estimated to have two stars or less,” says Govind Maksay from the foundation. “The 15 houses we studied were even worse – the average was 1.3 stars and a couple of them achieved no rating at all.”
The researchers surveyed each dwelling and calculated its energy rating. They modelled a series of upgrades to the building fabric: ceiling, wall and floor insulation, draught proofing, drapes and pelmets, external shading and double-glazed windows.
With all the measures in place, the houses jumped to an average of 4.3 stars, for an average cost of about $22,500.
However, the changes weren’t all equal, in either impact or cost. “On average, over 80 per cent of the rating improvement came from the insulation and comprehensive draught proofing,” Mr Maksay says, “but that constituted just 20 per cent of the total upgrade cost.” In contrast, double-glazing proved highly expensive for more limited benefit.
Although these findings vary according to the dwelling and the modelling undertaken, Mr Maksay says householders can learn important lessons from the study: seal your gaps and insulate your walls and ceilings.
“To really improve your star rating you have to tackle wall insulation, whether that’s with blow-in granulated rockwool or by removing the weatherboards or plasterboard and inserting batts.
“The other message is that there’s a difference between wimpy and comprehensive draught sealing. Really blocking up gaps and cracks has a big impact.”
If you live in an older house, your heating probably comes and goes like the wind. Choose your tactics carefully and you’ll bump up your rating at little expense. “It’s highly achievable for existing houses to get near the five-star standard. You can get a big bang for your buck,” Mr Maksay says.
With that advice in mind, an alliance of environment and welfare groups is launching One Million Homes, a retrofitting campaign aiming to transform half the Victorian housing stock over five years, beginning with low-income households.
Damien Moyse, from the Alternative Technology Association, says we have much room for improvement. Three in ten Victorian households are still using power-hungry electric storage hot water systems.
The scheme would cost an average of $2500 per house, Mr Moyse says. “Governments have already committed two-thirds of that under existing rebates and programs.”
A retrofitting scheme would cut greenhouse gas emissions and water consumption, and save householders about $290 per year. “It would make properties more liveable in the context of rising temperatures and more extreme weather events,” he says, “and target people who can’t afford to install some of these technologies.”
If you want even more impetus to insulate, visit the green building events scheduled during the State of Design Festival, from July 14 to 25.
Next weekend, Sanctuary magazine is setting up speed dating with sustainable architects and development firm Brutal Art is conducting green design workshops. The following weekend there’ll be open houses and courses in Castlemaine and Bendigo, all for free.