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Abstract
Globally, the building sector accounts for nearly 40% of energy utilisation, 30% of total greenhouse gas emissions and 25% of waste generation. Even though embodied emissions of building material production constitute a significant additional proportion of emissions, less quantification work has been done in this area compared to direct operational emissions of buildings. Furthermore, inconsistent methodological frameworks, and inaccurate or incomplete life cycle inventory data have hindered the adoption of methods to quantify the embodied emissions of building materials. The overall aim of this thesis is to improve upon existing methods and data for the analysis of embodied emissions in Australia in order to assess low-carbon solutions and scenarios for the built environment. The combination of input-output and process-based approaches using the input-output based hybrid life cycle assessment (hLCA) method enabled the evaluation of economy-wide greenhouse gas emissions of specific and low-carbon building materials. The integration of physical and monetary data via the combination of material flow, process and input-output data enabled a comprehensive assessment of recycled construction materials using the mixed-unit hLCA method. A novel approach to decompose results derived from mixed-unit and integrated hLCA was developed to distinguish life cycle emissions stemming from industries, products and processes. The hLCA methods developed have helped to provide a comprehensive and accurate assessment of building materials, to identify carbon hotspots in supply chains, and to enable scenario modelling for achieving economy-wide reduction of greenhouse gas emissions. Based on the economy-wide framework, a hybrid life cycle inventory database containing Australian embodied carbon data for building and construction materials was delivered. Scenario and comparison results from this thesis showed that low-carbon alternatives for construction materials (e.g. blended and geopolymer concretes, engineered wood products, electric arc furnace steel) and waste minimisation strategies (e.g. recycling construction and demolition waste) are ways for the construction industry to contribute to a more sustainable development in the wider economy. hLCA techniques are capable of delivering detailed analyses of embodied carbon emissions of the built environment that are useful to various stakeholders across government agencies and communities in their coordinated efforts to achieve a meaningful reduction in carbon emissions.