By Caroline Noller

LETTER: 19 October 2010 – Thanks for the recent news from the front desk “challenges are complex and multiplying” regarding the merit of increasing residential Star Ratings. It is a conversation the property sector could benefit from.

Mr [John] Eckert’s position is sound and rational and I support the notion that more whole of life research work is needed before we see further increases in home and other building operating energy rating requirements. It is possible to add more embodied greenhouse emissions to a building than is theoretically saved on heating and <!–more–>cooling.

A recent analysis of the capital and operational implications of moving brick veneer and cavity brick project homes from 5 to 6 Stars found that, in a Sydney climate, the annual savings delivered were theoretically 0.4 T CO2 per annum, however, 4.6 T CO2 were added to the building in additional insulation, glazing and sealing. This means that it would take 11.5 years to “payback” the embodied carbon to equal the incremental savings theoretically generated.

The principle issue here is certainty. As Professor Terry Williamson and Dr Paul Bannister have found, there is no certainty or correlation of actual with modelled performance – in either the commercial or residential sectors. Although the commercial sector is improving, my own personal experience is that it will be a few years yet until we see consistency in delivery of operational targets from design. The implications of this work and that of Williamson and Bannister is that we could indeed be following a path which is accelerating the carbon intensity of buildings rather than reducing it – particularly where there is no rock solid guarantee that the rating in design is delivered in real life.

By way of example, an alternative to consider could be targeting a reduction in the embodied carbon intensity of buildings through materials selection and design analysis. For example, for the same typical home noted above, changing the base-case timber wall studs to 100 per cent recycled aluminium wall framing would actually deliver an absolute saving of 8 T CO2 upfront – which is equal to 20 years of the notional operational saving.

Water heating, lighting, refrigeration and appliances are all key elements which need to be tackled in design of residential dwellings in addition to heating and cooling.

It would be refreshing to have conversations about a deemed to satisfy approach to carbon abatement that considers the whole life cycle of the building for all end uses as well as embodied. This approach would provide greater incentive and flexibility for developers and owners to invest in those conservation measures that most suit their lifestyles and as such have a greater commitment to them actually being delivered.

So, in conclusion – I agree, the challenges are complex and multiplying.

Caroline Noller

Sustainability Manager

Australand Holdings Limited