Mat 01 - Building life cycle assessment

Clarification of ‘Embodied carbon benchmark comparison’ - KBCN1819

The embodied carbon benchmark comparison must always be based on the latest appropriate LCA stage that corresponds to the BREEAM assessment stage being pursued. The purpose of the benchmark comparison is to assess outcome-based embodied carbon performance, using data that is representative of the building at the relevant assessment stage.

Assessment stage requirements

Interim (Design Stage) BREEAM assessments

• Where an interim / design stage assessment is being submitted:
  • The benchmark comparison may be based on a Technical Design LCA, where this represents the latest LCA available at that stage.
  • Benchmark results at this stage are indicative and intended to support design decision-making.

Final Post-Construction Stage (PCS) BREEAM assessments

• Where a final post-construction stage (PCS) assessment is being submitted:
  • Benchmark comparison credits can only be awarded where a Post-Construction Stage (PCS) LCA has been completed.
  • A technical design LCA alone is not sufficient to support benchmark comparison credits at PCS.
  • This is because the PCS LCA is the only assessment that reflects the materials and products actually installed in the completed building, and therefore the only suitable basis for outcome-based benchmarking.

If a PCS LCA is not undertaken, benchmark comparison credits cannot be awarded at final assessment, regardless of whether a technical design LCA was previously completed. This aligns with wider industry frameworks (e.g. RICS WLCA v2 and the UK Net Zero Carbon Buildings Standard), which anchor performance claims to as-built outcomes.

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