By David Clark
The new version 1.2 update of Green Star Design and As Built, to be released by the end of June, signals the Green Building Council of Australia’s (GBCA) intention to raise the bar for environmental and social performance of Australian buildings. While the update does not represent the radical step change that our industry needs (watch this space), it does introduce some welcome changes, closes a few loopholes and helps build capacity and skills in both design and construction.
The key changes are:
Minimum Greenhouse Gas Emissions Threshold
To obtain a 6 Star rating you now need to achieve a minimum 6 points for greenhouse gas emissions (and 3 points for a 5 star rating). While this is not a difficult target, it is the first time Green Star has set different minimum energy performance requirements for each rating bracket. As we transition to a low carbon future, it should surprise no one that these minimum rating thresholds will rise.
To be considered ‘world leading’ today a whole building, not just the base building, needs to be zero carbon. The GBCA has recently consulted with industry on a Carbon Positive Roadmap and I would hope that one of the key outcomes is that 6 star Green Star buildings will need to be zero carbon by 2020. Whether our industry is ready for this step change remains to be seen.
Building Air Tightness Testing
Building Air Tightness testing is now mandatory in the commissioning credit in the absence of any requirements in the National Construction Code. This has been introduced to build knowledge and capacity in Australia to design, construct and test buildings to be less leaky.
- Architects will need to better understand façade detailing, particularly vapour barriers and sealing details.
- Mechanical engineers will need to design ventilation systems that don’t rely on uncontrolled air infiltration to avoid overheating, reduce risk of mould and equalise pressure differences between spaces.
- Contractors will need to train their workforce to build for air tightness and to tape around services when they penetrate through membranes.
- Manufacturers have an opportunity to develop products to provide airtightness solutions cost effectively in Australia.
- The number of air tightness testing companies will increase and the costs will therefore decrease.
Europe has been doing this for years (and PassivHaus raised the bar significantly) so the knowledge and skills exist overseas – we just need to apply these in an Australian context. As the dataset of test results increases, expect to see Green Star introduce more stringent air tightness thresholds which are appropriate to different building types and different climates.
Life Cycle Assessment (LCA)
The amount that operating energy contributes to the points achieved from Life Cycle Assessment (LCA) has been capped. Too many projects were scoring points in the Materials category by writing a report without really doing anything to reduce the environmental impact of the materials used. The LCA pathway was introduced in 2015 to build capacity and skills in the industry but an unintended consequence was obtaining Materials points too easily through operating energy savings (which are already scoring points in the energy category). The update is a pragmatic step in the right direction to reduce double counting of operating energy and shift the focus onto specifying lower impact materials. Future updates of Green Star will likely eliminate operating energy entirely from the LCA pathway points achieved for materials.
With the welcome increase in Cross Laminated Timber (CLT) manufacturing and construction in Australia a new prescriptive pathway has been introduced in the Materials category for certified structural timber.
There is increasing awareness of and action on sustainable and responsible supply chains through initiatives such as Environmental Procurement Declarations, the Declare label, the new ISO 20400 for Sustainable Procurement and the founding of the Australian Sustainable Supply Chain School. It is therefore likely that more stringent requirements related to the environmental and social impact of all materials used in Green Star buildings will be introduced in the future.
Responsible Construction Practices
Suicide and mental health of construction workers is a major issue and every year 190 Australians in the construction industry take their own lives. Construction workers are six times more likely to die from suicide than an accident at work (MATES in Construction). Green Star has now introduced a “Responsible Construction Practices” credit which encourages Contractors to provide mental and physical health programmes on construction sites. This is a very welcome initiative and recognises that the health and well-being of the people constructing buildings, as well as those living and working in those buildings, must be addressed.
The changes outlined above are a step in the right direction. They don’t go as far as we need to, but within the limits of what is possible for a minor update to the rating tool they represent a pragmatic and timely response while work goes on to define what Green Star should look like in 2019. I encourage you all to assist in shaping a more sustainable built environment by participating in future GBCA industry consultations and workshops.
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