Towards comparable environmental product declarations of construction materials: Insights from a probabilistic comparative LCA approach

The comparability of environmental product declarations (EPDs) and the heterogeneity of their life cycle assessment (LCA) methods are considered the main challenges facing the credibility of results. In this study, a probabilistic tool was proposed and developed to gain insight into what is necessary to achieve the unrealized vision of comparable EPDs. The developed framework incorporated several uncertainty sources, such as life cycle inventory and allocation rule choices, and data quality and variability of the input parameters in a consistent way. Then, the framework was applied to a case study of concrete mix designs. The comparative results of the industry benchmarks and the mix design population show that for a given compressive strength level, all the ternary blended cement mixtures have a statistically significant lower GWP than that of the industry-average benchmark. However, a 40 kg CO(2)eq difference in the comparative GWP results of portland cement and binary mixtures (with an average impact of 345 kg CO(2)eq) may not result in a statistically significant difference. The major source of variation in the stand-alone LCA results comes from the methodological choice of database selection with portland cement inventory data. However, the impact of methodological choices on the variance of the comparative results is trivial and the variability of portland cement content dominated the variance. Therefore, as long as the LCI database is representative of the context, the methodological choices may be a minor concern in the comparative analysis.