By Tina Perinotto
8 April 2010 – The updated Building Code of Australia is about to hit the market next month – on 1 May – but many architects and consultants have little idea how significant the changes will be, especially for glazing commercial buildings.
What’s likely is a huge reduction of glazing allowed – up to 40 per cent – and a “period of pain” for architects while they adjust to the reality that they need “at last” to take passive design seriously.
That’s the view of the few experts who have been able to grapple with the complexity of understanding the BCA 2010, especially the provisions in Part J which relates to both commercial and residential buildings.
It is also the view of consultants who have attended one of the series of seminars to explain the new BCA being conducted by the Victorian Building Commission in Victoria, and nationally by the Australian Building Codes Board.
One consultant told The Fifth Estate that it would take quite a while “to get my head around this. I will have to explain to architects and builders how to interpret the changes.”
A key concern of the changes – agreed by the Coalition of Australian Governments and to be implemented in May by all states and territories except the NT – is to shift the focus in new buildings from energy efficiency to greenhouse gas savings.
Most affected will be commercial buildings and the cities’ glass boxes that could come in for the biggest changes.
Caroline Pidcock, a leading sustainability and architectural commentator and current industry representative member of the ABCB, said it was time for a major rethink on glazing.
“We have the most inefficient buildings in the world. Why should we have office buildings 100 per cent glazed,” she said.
Ms Pidcock said it was not automatic that glazing needed to be scaled back dramatically.
The use of sophisticated thermal modelling could meet the “deemed to satisfy” provisions in the BCA by proving that environmental outcomes had been met in some other way.
“The best thing about the building code is that it is performance-based. Good thermal performance is not tick-a-box because of so many interactions between the various elements.
For more simple buildings, such as warehouses for instance, it was possible to take the “lazy route” and use the prescriptive approach, Ms Pidcock said, “But it won’t give you as intelligent a result as thermal the modelling route.”
Michael Shaw, an associate Architectural ESD consultant with Meinhardt and consultant to the Australian Institute of Architects for its submission on the BCA changes, had a different view.
He told The Fifth Estate that in his calculations the percentage reduction in allowable glazing would be 40 per cent and that he believes the reduction in glazing will be hard to avoid.
“If 50 per cent of facade could be glazed in BCA 2009 and 30 per cent of facade could be glazed in BCA 2010, then this is a 40 per cent reduction in glazed area allowance.”
In his view the most difficult aspect of the new version of the BCA was the “big reductions in allowances of heat-flow through vision glazing in facades” such as windows and roof lights.
“The allowances have been significantly reduced, particularly in the cooler climate zones 4, 6, 7 and 8.
“An even bigger concern for me is the reduction in glazed area allowances for hotels (class 3) and aged care (class 9c) facilities,” he said.
The AIA said, in its submission to the Australian Building Codes Board, that there could be unintended consequences in the provisions.
“The Institute understands that it was never the intent that the provisions proposed for the BCA 2010 would limit, or worse, proscribe good or best practice,” the submission says.
“It is evident, however, that this will be the unintended consequence of some of the proposed measures, and this is not addressed in the CRIS. This is a matter of significant concern which should be addressed before provisions are included in the BCA that will preclude good design outcomes.”
Perhaps better would have been to focus more on improving the quality of buildings services, the Institute says.
A key concern with cutting down on glazing would be a loss of amenity.
The submission continues: “Windows provide psychological amenity through views, a perceived connection between interior and exterior, and access to natural daylight.
“The benefits of natural light and outlook are increasingly being reported on in ‘green’ buildings for their effect on occupant wellbeing.
“This is also being linked to productivity gains, and these aspects of windows are recognised in industry-acknowledged tools such as Green Star, yet ignored in this report.”
The Institute supports actions to reduce greenhouse gas emissions, it says, but “not at the expense of the amenity of the built environment”.
The proposals are “ill considered” and need to be comprehensively reviewed.
General manager of the ABCB, Ivan Donaldson, told TFE that the impact of the changes would be minimal “if any” on the better designed commercial buildings.
However there would need to be greater awareness of the need to consider Section J provisions for the bottom end of the market, he said. For manufacturers and contractors, it would mean the emergence of more innovative products and practices.
On the glazing provisions, Mr Donaldson said that the BCA was a performance-based code and “not a mechanism for driving prescriptive solutions”.
“If some developers choose the cheapest construction route, they could legitimately reduce glazing areas in non-residential buildings. This choice has always been available to them but has rarely been taken up because of its adverse impact on the marketability of the building.
“Walling systems are generally cheaper than glazing systems, but typical glazing areas have remained relatively unchanged over the years due to light penetration and market forces for ambience.
“Designers will generally be able to comply with the latest BCA energy efficiency requirements without reducing their preferred window sizes by selecting higher performing glazing systems.”
He added that a proposal to require higher performance from shop windows had not been adopted because of the industry feedback.
The most significant changes to Part J of the ABCB included that the focus was now “clearly on greenhouse emission reduction rather than only on energy efficiency which is just one part of reducing emissions”.
Energy sources, particularly renewable energy sources, would therefore become more important, in addition to using energy efficiently.
He said, “Generally the provisions have been made more demanding across the board in order to achieve the COAG target of a 2:1 benefit to cost ratio.”
Mr Donaldson said that specific changes in scope included constraints on:
The heating energy source for space heating. “Basically restricting the use of resistance electricity and only using fuel oil where gas is not available at the allotment boundary. Electricity for refrigeration and reverse cycle heat pumps is allowed because of its high coefficient of performance.
The heating and pumping energy source for swimming pools and spas. Again restricting the use of resistance electricity for heating pools and spas while requiring time clocks for pump controls. However swimming pools for houses may only be heated by solar as a Deemed-to-Satisfy provision.
The maximum allowances for lighting energy within dwellings. 5 Watts/m2 as a base for inside the dwelling, 4 W/m2 for a verandah and 3 W/m2 for a garage. These base allowances can be increased if certain control gear is fitted.
Chief executive officer of the Master Builders Association, Wilhelm Harnisch, said it was clear that Australia needed to reduce its emissions but the big question was who would pay.
“The concern we’ve expressed is the inequity of focusing purely on new buildings when in fact the major emitters are existing buildings.
“While the government has provided some assistance for small to medium businesses to upgrade their energy and water usage, the reality is that the vast majority of existing buildings need to be properly attended to if there is going to be a serious attempt to reduce the carbon footprint from buildings.
Mr Harnisch also called for more consistency between the rating tools.
He also said that despite the government’s assurance that the new regulations had to pass the RIS test – that is that the cost benefit equation would be positive – the results would be negative. Yet the government had chosen to go ahead with the changes
On a broader policy issue, however, Mr Harnish said it was clear that Australia needed to reduce its carbon footprint, and that in the absence of a carbon trading system all eyes were now turned to the property sector to deliver the savings.
“There is a broad community benefit in reducing Australia’s carbon footprint, and therefore it is a responsibility and cost that needs to be borne by the community in general.”
He called for more assistance to the industry and said that the MBA backed an accelerated depreciation scheme, a measure the Property Council of Australia was also calling for.
Archicentre NSW and ACT state manager Angus Kell said the BCA was typically difficult to interpret and required specialised consultants.
“It’s very difficult. The Building Code refers to 140 Australian Standards. If the average person in the street thinks they can get their heads around the building code, they would be wrong.”