Comparison of two life cycle assessment tools for infrastructure projects in Sweden : A case study at Atkins Sverige AB

Abstract: The construction sector has a large impact on the environment and is an industry where sustainable development is of importance moving forward. It requires large amount of materials, and is both waste and carbon intense. The greenhouse gas emissions from production in the construction industry was in 2017 estimated to 12,2 million tonne CO2-eq, representing 19% of the emissions in Sweden, and it has been estimated that infrastructure and foundations represents 60% of the emissions in the production phase. Since Sweden has the national objective of being climate neutral by the year 2045, climate calculations are of relevance for the sector in order to make more sustainable choices and increase the possibility to meet the target of becoming climate neutral. Atkins Sverige AB is a design and engineering consultant company mainly working with infrastructure who is currently in the process of choosing a software tool for climate calculations on the external consultant projects, and has therefore requested a comparison and evaluation of two simplified LCA- tools; Bidcon and Klimatkalkyl. The aim of this thesis was to provide a recommendation on which of these software Atkins Sverige should use for climate calculation on external consultant projects. This was conducted by assessing current industry praxis and comparing and evaluating the two software, both qualitatively and quantitatively. An evaluation of the tools was conducted by developing a framework for evaluation of simplified LCA-tools using an MCA approach, and both tools was applied to an existing project in a case study. The results from the case study indicate differences in emission factors between the software, where Klimatkalkyl had a result 21% lower than Bidcon, and there were large differences in potential impact between some of the resource categories in the two software. The largest difference in results was found for earthworks and demolition, with Klimatkalkyl having 220 and 111 tonne CO2-eq less than Bidcon in these resource categories, which represents 26% of the emissions in the Bidcon calculation. For Bidcon where more data was available, a second calculation was conducted, calculating the potential impact from the data which was not available in Klimatkalkyl. The results indicate that 38,6% of the total potential environmental impact of the project is excluded due to the lack of data in Klimatkalkyl. Out of the resources excluded from Klimatkalkyl, those with the highest potential impact was kerbstones, demolition, paving stones, filling around pipes, and wells. The evaluation framework had seven categories and the results indicated that three aspects were equal between the software; stakeholder acceptance, transparency and data quality, and informative. Klimatkalkyl received higher score in one category, life cycle perspective and environmental focus, while Bidcon received higher score in the remaining three categories; comprehensiveness of data, modification and user friendliness. Comprehensiveness is considered the most crucial category in the evaluation, and since the case study indicated 38,6% of emissions excluded from Klimatkalkyl, Bidcon is the recommended software for Atkins Sverige to use. Further, with Bidcon being more user friendly and offering more options for modification, it is considered easier to minimize errors in the calculations compared to Klimatkalkyl.