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A variety of methods can be used to compile a life cycle inventory (LCI) as part of a life cycle assessment (LCA) study. Hybrid LCI methods attempt to address the limitations inherent in more traditional process and input-output (IO) LCI methods. This paper provides an overview of the different hybrid LCI methods currently in use in an attempt to provide greater clarity around how each method is applied and their specific strengths and weaknesses. A search of publications quoting the use of hybrid LCI was undertaken for the period from 2010 to 2015, identifying 97 peer-reviewed publications referencing the use of a hybrid LCI. In over one third of the literature analysed, authors only refer to their analysis as a hybrid LCI, without naming the actual method used, making it difficult to fully understand the method used and any potential limitations. Based on the way in which the various hybrid methods are applied and their existing use, the authors propose a set of clear definitions for existing hybrid LCI methods. This assists in creating a better understanding of, 2 and confidence in applying hybrid LCI methods amongst LCA practitioners, potentially leading to a greater uptake of hybrid LCI. KeywordsLife cycle assessment; life cycle inventory analysis; input-output analysis; process analysis; hybrid analysis.

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16It is expected that biodiesel production in the EU will remain the dominant contributor as part 17 of a 10% minimum binding target for biofuel in transportation fuel by 2020 within the 20% 18 renewable energy target in the overall EU energy mix. Life cycle assessments (LCA) of 19 biodiesel to evaluate its environmental impacts have, however, remained questionable, 20 mainly because of the adoption of a traditional process analysis approach resulting in system 21 boundary truncation and because of issues regarding the impacts of land use change and N 2 O 22 emissions from fertiliser application. In this study, a hybrid LCA methodology is used to 23 evaluate the life cycle CO 2 equivalent emissions of rape methyl ester (RME) biodiesel. The 24 methodology uses input-output analysis to estimate upstream indirect emissions in order to 25 complement traditional process LCA in a hybrid framework. It was estimated that traditional 26 LCA accounted for 2.7 kg CO 2 -eq per kg of RME or 36.6% of total life cycle emissions of 27 the RME supply chin. Further to the inclusion of upstream indirect impacts in the LCA 28 system (which accounted for 23% of the total life cycle emissions), emissions due to direct 29 land use change (6%) and indirect land use change (16.5%) and N 2 O emissions from fertiliser 30 shown, for instance, that inputs from the 'Other Chemical Products' sector (identified as 34 phosphoric acid, H 3 PO 4 ) into the biodiesel production process represented the highest carbon 35 emission path (or hot-spot) with 5.35% of total upstream indirect emissions of the RME 36 biodiesel supply chain. 37 38

There is an increasing pressure on cities worldwide to accommodate the increasing population.Most cities are likely to expand in the coming decades and this expansion will probably take place as low-density neighbourhoods. It is therefore crucial to assess the energy demand and related greenhouse gas emissions of such development from a comprehensive perspective. This paper uses a representative low density case study neighbourhood near Melbourne, Australia, to assess its energy consumption and greenhouse gas emissions over 100 years. Different housing typologies, such as row houses and low-rise apartment buildings, are tested. Results show that the energy required to produce and replace building materials and infrastructures constitutes nearly 26.9% of the total energy consumption while operational and transport requirements represented 39.4% and 33.7% respectively. Variations to the housing types reveal that apartment buildings reduce the energy consumption per capita by 19.6% compared to the one-storey single family detached house typical pattern. Regardless of the uncertainty in the data, the main conclusion is that each of the embodied, operational and transport energy demand and associated greenhouse gas emissions should be lowered in order effectively reduce the environmental impacts of new urban neighbourhoods.