Weighting of Environmental Impacts in Australia for BPIC and the Building Products Life Cycle Inventory (also available from Building Products Life Cycle Inventory).
This report was produced as one of the components of a three-year project jointly funded by the Building Products Innovation Council (BPIC) and AusIndustry to establish a toolkit of resources that will permit comprehensive Life Cycle Assessment (LCA) of building and construction materials and products, building elements and assemblies, and whole buildings in Australia.
The final stage in an environmental impact assessment entails bringing together the disparate environmental impact categories that are all measured on different scales. Moreover, the different environmental impacts are usually not considered equally important to Australian citizens, and different impacts matter more in different locations. It has been common for LCA practitioners to use the Ecoindicator method quite routinely without appreciating that this method uses European relevant characterisation methods and European average weighting assumptions.
This report describes the approach taken to developing a set of regionally relevant and Australian average weighting factors, which reveal how Australian stakeholders subjectively judge the relative importance of different environmental impacts in different locations/climates around Australia.
To date, it has been left to each LCA practitioner or tool developer to reach their own conclusions about the weighting of impact categories in the way they assess and score impacts. Frequently practitioners are unaware that they are making weighting decisions implicitly in their methodologies. For instance, a decision to treat all impact categories the same is a weighting choice and so is the decision to focus on just one parameter like greenhouse gas emissions (GHGs). Weightings allow a range of factors to be considered and reconciled together e.g. GHGs rated against water scarcity for a desalination plant.
The method used derives weightings from 11 workshops conducted around Australia, taking in major population centres, spanning all major climate zones, states and territories, and incorporating some regional centres.