Embodied Carbon Tool Database Comparison Report

Canada is rapidly scaling embodied carbon requirements across municipal, provincial, and federal initiatives, with longer-term integration being explored for the National Model Codes 2030. As these policies expand, confidence in Whole Building Life Cycle Assessment (WBLCA) results becomes essential. This report, funded by the National Research Council of Canada (NRC), supports that need by examining why modelling the same building with the same quantities can produce meaningfully different results depending on the software tool used.

Embodied Carbon Tool Database Comparison provides a detailed, material-level analysis of the underlying databases and default modelling assumptions used by five leading tools commonly applied in Canada and across North America: One Click LCA, Athena, Tally, EC3, and BEAM. It traces variation to identifiable drivers, including differences in underlying datasets for product-stage impacts (A1–A3), such as EPD-based profiles versus more generic LCI-based profiles, as well as differences in downstream life cycle stage assumptions such as transport (A4), construction waste (A5), service life and replacements (B4), and end-of-life pathways (C1–C4). The analysis also examines inconsistencies in biogenic carbon modelling and non-GWP environmental impact categories across tools. The report includes a detailed analysis of the number of data points per material category, providing a clear picture of the breadth and depth of data coverage across each software tool and how they compare.

This report is intended as a neutral, technical comparison, not an evaluation of tool quality or performance. The tools included were developed independently, drawing on different datasets and modelling assumptions, with limited coordination or standardization across the industry. By clearly documenting where results and default assumptions align and where they diverge today, the findings provide a practical evidence base for coordinated improvement.

With a clearer understanding of current alignment and divergence, the data can inform future efforts to define nationally consistent baselines and default modelling assumptions that tool providers can easily reference and adopt for Canadian projects. The report highlights opportunities to prioritize Canadian-relevant industry-average baselines for key material categories to improve consistency in product-stage (A1–A3) results, alongside standardized national default assumptions for later life cycle stages, including a pathway to align modelling from A4 through C. Over time, this approach can reduce variability across tools, strengthen comparability for benchmarking, and support credible target-setting and policy implementation in Canada, with potential relevance for the United States and other regions as similar market needs emerge.

This technical report is intended for whole building LCA practitioners, policymakers and standards bodies, tool providers, teams doing embodied carbon benchmarking across portfolios, and manufacturers and EPD stakeholders, plus anyone else working with WBLCA results who wants a clearer view of where tool outputs align or diverge and what that means for comparability, benchmarking, and target-setting.