Brightcon 2026, hackathon and courses

Highlights/Discussion Points:
- Introduction of the problem
- How to go about assessing this issue with BW
- Results: Uncertainty due to price variance in economic allocation. Comparison to other sources of uncertainty in LCA.

Concise Description
Economic allocation is widely used in life cycle assessment (LCA) to distribute inputs and emissions among co-products, yet it introduces a less visible source of uncertainty: prices (of co-products) can change over time, across markets, and trading relationships. This means that, unlike physical allocation factors, economic allocation factors are not fixed parameters but stochastic quantities that influence the impact results. While critics argue that economic allocation is therefore unsuitable, proponents see it as best reflecting the economic drivers of the impact and tout its ability to capture complex attributes of product or service quality.

Various works discuss the different types of allocation and the uncertainty arising from the choice between them. However, to the author’s best knowledge, no quantitative study of the uncertainty from price variance in economic allocation has been conducted. Therefore, in this work, I investigate the uncertainty arising specifically from economic allocation in a Brightway-based Monte Carlo workflow that propagates price variability through co-product allocation and downstream impact assessment.

Using macroeconomic data to derive reasonable variations in co-product prices, this study quantifies allocation uncertainty in activity-level impacts in the ecoinvent database. I show that economic allocation uncertainty can be substantial and is not uniform across activities. Furthermore, I will compare the uncertainty due to price variance in economic allocation with traditional parameter uncertainty and other sources of uncertainty, such as the truncation error in product LCA.

The full assessment pipeline is, or will be made, fully available in a GitHub repository. The assessment is fully based on open source software, and the presentation will highlight how to go about this.