Green Star D&AB version 1.2 Opportunities for Improvement

DAB 1.2

The Building Life Cycle Impact Reduction credit in version 1.2 has significant gaps outlined below, detailing why the B6 points cap and focus on other modules doesn’t work.

eTool disagree with the method selected for the version 1.2 of the Green Star Design and As Built as it could lead to poor outcomes for the planet. Some examples are presented below:

Example 1:

Design team works hard to identify low impact materials that reduce the overall impacts of the design by an average of 10% per indicator in the LCA credit. Operational energy efficiency is resulting in a 50% saving. This results in about 3 points in the LCA credit for materials choices and 3 points for energy (B6). They decide to install a PV system that increases the operational energy saving to 90%. They achieve 8 extra points in the GHG calculator. But the PV results in a 10% average increase in impacts in other life cycle modules in the LCA credit. So they gain 8 points, and lose 3. At this point, the low impacts materials could be removed with no effect to the total Green Star points. So the design team decides to not pursue the original low impact material choices because excluding them will make no difference to their Green Star points. Although this could be considered as an “Edge Effect” considering 20% of Australian households now have PV, in the residential space it’s not at all uncommon potential scenario, particularly when dealing with high performance buildings that are aiming for best practice.

Example 2:

Similar to example one with a different technology. Design team of a residential multi unit dwelling building has focussed on low impact materials, and is achieving a 30% reduction in energy consumption through energy efficiency. They’re currently achieving 4 points in the LCA credit (1 for materials, 3 for B6) and 5 points in the GHG credit. They look into replacing the electric instantaneous solar hot water units with electric heat pumps. They find out it’s only possible with large central unit. The design changes required for the hot water ring main (additional service risers, copper ring main, pumps, insulation etc.) and the heat pump itself (including refrigerants) adds significant impacts to the materials (reduce LCA points by 1) but results in a large positive impact in the operational energy (20% saving increases GHG points by 4). Design team could now remove the low impact materials with no effect to Green Star points.

Example 3:

If the GHG calculator excludes plug loads from the assessment, projects that add technology or design features that reduce plug loads may be penalised for those features in the Green Star credits (regardless of the life cycle benefits). An example would be additional PV (not required for integrated equipment).

Example 1 and 2 are particularly problematic as they may actually drive less effort and innovation in materials etc which is against the principle of fostering optimisation in all life cycle modules.

Lack of Normalisation and Weighting in the Green Star LCA calculations:

Normalisation and weighting should be seriously considered for the points calculation. The method currently advocated in the credit (no normalisation and equal weighting) is somewhat contradictory to accepted LCA methodology. It has also already lead to some potential adverse penalties in the LCA credit.

An example that best illustrates this is the application of a large solar array on a buildings which led to an increase in ODP (more than 10%) in the characterised results. In the particular example (which we can’t publicise) when the results were normalised the reference buildings had GHG emissions equivalent to 500 Australian persons average emissions. The ODP on the other hand was 1.9 persons average emissions. So the solar array was reducing the GHG by 100’s of person’s average GHG emissions, but only increasing the ODP by 0.19 persons average emissions. So use of characterised results was effectively saying “we will reward a building more if it reduces the impacts of ODP by 0.19 person’s average emissions but increases GHG emissions by hundreds of average person’s emissions”. Potentially this would be justified if ODP was a far bigger environmental problem than GHG. Weighting could be applied to test for this (and the established weightings systems globally and in Australia seem to suggest GHG is a bigger problem). ISCA have a normalisation and weighting system which could be drawn upon by the GBCA. Similarly, BPIC established normalisation and weighting figures that could be used as a first pass by the GBCA.

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Trackbacks & Pingbacks

  1. […] and quantifying points achievable via the ‘Super credit” could help to close some gaps of the Green Star Design and As Build 1.2 rating […]

  2. […] For LCA devotee like eTool, it gives hope that the new rating (Green Star for new buildings) will bring the circular economy thinking within Green Star to a whole new level. It is a great chance to close gaps in the previous rating “Green Star Design and As Built version 1.2” as pointed out by eTool feedback on the Material Life Cycle Impact Reduction credit. […]

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