Overview and recommendations for regionalized life cycle impact assessment

Area of Science:

• Life Cycle Assessment (LCA)
• Environmental Science
• Sustainability Science

Background:

• Regionalized life cycle impact assessment (LCIA) methods have advanced significantly but face challenges in application, robustness, and validity.
• The UNEP/SETAC Life Cycle Initiative's working group addresses the status of regionalization in LCIA methods.

Purpose of the Study:

• To provide an overview of the current state of regionalization in LCIA methods.
• To offer guidance and recommendations for harmonizing and supporting regionalization in LCIA.
• To aid developers of LCIA methods, LCI databases, and LCA software.

Main Methods:

• A survey was conducted among developers of regionalized LCIA methods.
• Key areas surveyed included spatial resolution, input parameter data, native resolution limitations, data alignment, aggregation methods, and uncertainty assessment.
• Recommendations were formulated based on survey results and expert discussions.

Main Results:

• Most regionalized LCIA models have global coverage, with native spatial resolutions often dictated by input data availability.
• Characterization factors (CFs) are typically aggregated to the country level using annual flow quantities or proxies.
• Uncertainty and variability are often not implemented in LCA studies, and there's no consensus on whether finer native resolution reduces uncertainty.

Conclusions:

• Regionalized LCIA methods require transparent, consistent data with standardized formats and metadata.
• Characterization factors (CFs) should encompass both uncertainty and variability.
• Both native-scale and aggregated CFs (weighted averages) should be provided to enhance transparency, consistency, and robustness in LCIA.