Embodied carbon assessment and decision making under uncertainty : case studies of UK supermarket construction

Estimates of the embodied carbon of buildings are resource intensive to produce and are subject to a wide range of uncertainties. Much of the time spent conducting an assessment is allocated to collate quantities of materials. Carbon factor data are a further important input to the assessment. A range of possible sources of carbon factors are available and these display high variability both in magnitude for a given material and also in terms of data quality. These features impair the use of such assessments in attempts to reduce carbon emissions associated with buildings. This research presents a simpler means of producing embodied carbon estimates and assesses the impact of uncertainty to improve decision making about carbon reduction, in the specific case of supermarket buildings. This approach is applied to a number of case studies of buildings constructed by Sainsbury’s Supermarkets Ltd. in the UK. A new approach has been developed for estimating embodied carbon using Building Information Modelling as a source of material quantity data. The approach demonstrates how establishing a machine-readable link between this data and carbon factor data, for example from Environmental Product Declarations (EPDs) facilitates semi-automation of an important step in the assessment process. In comparison to more traditional, manual methods, this new method offers improved efficiency by reducing repetition of data entry. The thesis also examines the possible effects of uncertainty and the analysis has shown that despite recent efforts to increase standardisation of EPDs across Europe, significant uncertainties remain. An approach recently applied in related fields of environmental assessment, which combines qualitative and quantitative assessment techniques, is used to show how these effects may be better understood and mitigated. The value of this approach is demonstrated by applying it to the results of comparative embodied carbon assessments of the kind that might typically be used to support the design of low carbon buildings.