Published in Green Magazine, Issue 16
An eight-star energy-efficient house touted to be “Australia’s first zero-emissions home” was opened to great fanfare this April.
It’s a huge leap forward from 1990 when houses averaged about 1 star on the Nationwide House Energy Rating Scheme (NatHERS) scale. Before the introduction of national energy efficiency regulations in 2003, less than one per cent of Australian houses achieved the current standard of 5 stars (which rises to 6 stars on May 1, 2011) however a 2006 study by RMIT’s Centre for Design suggested Australia was aiming too low after finding American and British homes designed for comparable climates would be rated at an average of 7 stars.
So should we be worried, ashamed, pleased or dismayed with our star rating system? Is it a relevant measure and is the Master Builders Association right to say greater efficiencies could be achieved by improving older homes first?
The CSIRO designed and built the zero-emissions (AusZEH) house with partners that include Henley Property Group and Delfin Land Lease, and its experts estimate 13% of Australia’s greenhouse emissions come from home energy use.
If all the new housing in Australia was built to the same standard for the next nine years, the country would save 63 million tonnes of greenhouse gas – equivalent to taking all of Australia’s private cars off the road for more than two and half years.
But drive around any new housing estate in Melbourne’s outer west – the third fastest growing area in Australia – and you will see row upon row of homes with heat-absorbing, dark-tiled roofs and no eaves. They may meet the 5-star standard, but they will need a lot of air conditioning to make them liveable.
“Without basing the star rating system on performance, it is meaningless,” believes Jan Brandjes, a Dutch-born, Canadian-trained expert in sustainable home design.
He is keen to promote performance-testing of houses because he believes the software used to assess star ratings assumes standards that are rarely achieved.
“The software assumes a building is (air) tight but there is no way of checking this. It addresses the design issue well but doesn’t address way a home is constructed.
“If the insulation is not put in right or it has gaps all over the place, it will be leaking air like a sieve; as long as they leak, no amount of double glazing will keep the energy out of those holes.”
Henley Homes’ energy and sustainability specialist Adam Selvay agrees.
“I have tested about 20 homes and you see a wide range of leakage rates,” Selvay said.
“I would like to see the Air Change per Hour rating given a certain star rating so there is some benefit for putting in the effort to get it right; at the moment there is no incentive to builders to do this.
“[The software] also doesn’t take into account the carbon emissions or the type of heating you use.”
Henley Homes can build the same zero-emissions four-bedroom dwelling on any suitable block for about $315,000 – that includes double glazing, a 6kW solar power, solar heating, extra insulation, retractable shading and a wafflepod concrete slab.
The wafflepod slab incorporates polystyrene under the concrete for extra insulation and adds half a star to the home’s rating. However, the home’s air-tightness adds nothing to its rating.
Brandjes feels so strongly about this he now works in the business of blowdoor testing – checking the air-tightness of homes by blowing air through the sealed up front door and checking how much is leaking out.
“I’m not saying blowdoor testing is the be-all and end-all but it’s one of the tools that can be used.”
He tested the zero emissions house, which is now spot on (if the Air Change per Hour rate drops too low, the quality of air in a home is compromised and can risk the inhabitants’ health).
However, two award-winning homes he has checked that were built to seven-star designs failed to meet even a 5-star standard – one ranked as low as 2.5-3 stars.
“We need to address two areas – the software needs to include performance-based testing, and we need to educate builders in the importance of sealing gaps.”
The Master Builders Association believes it is already addressing the issue of training builders, with the Green Living training scheme launched in Victoria in 2005 and since rolled out into NSW, Tasmania and WA.
However, the group’s vocal stance in the Federal election was due to way the star rating system is being implemented.
“With the move to Six Star it is imperative that the industry is properly consulted and allowed to prepare for any new regulations,” Master Builders Association of Victoria deputy executive director Radley de Silva said.
“The cost involved also needs to be managed (and) there also needs to be greater consumer education and incentive to reduce energy consumption – as there has been with water use.
“There seems to be this focus on increasing star ratings on new housing stock but we believe there is greater opportunity to improve the star rating on existing stock. This would be a more sensible way of improving the average star rating across the board.”
This is the area that Mandatory Disclosure aims to cover – by making it compulsory for all homes to be star rated at point of sale or lease. The scheme has been running in the ACT since 1999 and is due to be introduced nationally on May 1, 2011.
However Brandjes see the current gaps in the system as becoming potentially disastrous when mandatory disclosure starts.
“It’s bad enough that someone spends money on a 5-6-7- star home then finds their energy bills are still high, but if every home that is sold has to be star rated, on what are they going to base the assessment – on the design? How will they assess insulation? And who’s going to do this – if people sell their home every seven years then that’s about 1.2 million homes a year – we don’t have the manpower to do that.”
The not-for-profit Association of Building Sustainability Assessors – which trained the home assessors for the now-defunct Green Loans scheme – believes its 6500 members across Australia can do the job – but agrees the federal government needs to hurry up and decide precisely what the job is.
“It’s a federal scheme but the states will be implementing it … at the moment there are a lot of different schemes and checklists – it all gets a bit messy,” ABSA chairman Wayne Floyd said.
ABSA has already released its concept model for mandatory disclosure, which states: “It is imperative to improve the existing housing stock … as new homes only contribute 2-4% of the total market. Existing homes can be rated using the NatHERS tools if a plan is readily available, and if not, there is already innovation that will allow this to be done without a plan.”
In the ACT, assessments take into account features such as building fabric, window design, orientation, air leakage and cross ventilation.
Another useful tool, Floyd suggests, are infrared cameras.
“It shows straightaway which windows are leaking air or where there’s no insulation in the walls without being invasive,” he said.
However, when this is sorted out, an even greater challenge looms – how to assess energy used by household appliances.
“When you look at appliances it gets really messy,” Floyd said. “Because it comes down to not just what you have in the house, but how you use those appliances.”