Mat 01 - Building life cycle assessment

Early design phase LCA submission – Modified planning applications - KBCN1893

Requirement  In the Mat 01 Methodology, M1.2 requires the early design phase LCA to be completed and submitted to BREEAM within 20 working days of submission of the planning application.  Intent  This requirement is in place to ensure that the LCA is carried out during the early design stages and can meaningfully influence material selection and key design decisions, before the planning application fixes significant aspects of the external specification.  The timeframe of 20 working days post-planning submission is a concession to allow project teams to collate the LCA evidence for submission to BREEAM.  Submission of the planning application  In this context, this is the application that specifies and fixes the external products and materials that are considered in the LCA. By default, this is considered as the first application.  However, it may also be: 

• A supplementary modified application, where a staged submission process is used 

• A replacement modified application, due to a major redesign 

Where the requirement is applied to a supplementary or replacement application, the project team must provide additional evidence to demonstrate that the intent is met.  Additional evidence 

• Confirmation of the date of the original planning application and the date of the modified application. 

• A description of what the modified application changes, with reference to the relevant submission documents. 

• Evidence that the modification significantly affects external products or materials specification, e.g. revised elevations, façade specification, external material schedules 

• Justification of how the early design LCA submitted in relation to the modified application was still capable of influencing relevant design decisions

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Life Cycle Assessment – Similar buildings approach (GN20 – Section 4) - KBCN1834

Where multiple buildings are included within the scope of a single BREEAM assessment following the Similar Buildings approach, in accordance with Section 4 of GN20, unless identical, each building must be assessed and reported separately within the LCA.  Where all buildings are demonstrably identical in design and specification (and differ only in scale), a representative LCA approach may be used (see KBCN1890). Shared elements (e.g. substructure, external works, or building services serving multiple buildings) may be apportioned between buildings using a reasonable and transparent method (e.g. by gross internal area or other appropriate project-specific metric), in line with recognised industry approaches. For the purposes of BREEAM benchmarking under Mat 01: • The results submitted to the platform must represent a single building, not a combined site-wide result. • Where multiple buildings are included within an assessment, the worst-performing building (in kgCO₂e/m²) must be used for benchmarking in line with the Similar Buildings methodology (section 4.2 of GN20). Full evidence must be provided to demonstrate: • That all buildings within scope of the assessment have been included, with individual LCAs completed for each building, and • How results have been separated and, where relevant, how shared elements have been allocated.

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Rationale: In line with Section 4.2 of GN20, BREEAM issues must be assessed for each individual building, with credits awarded based on the worst‑performing building for each assessment issue. The Similar Buildings approach therefore remains an individual‑building assessment methodology and does not constitute a site‑wide assessment, even where multiple buildings are included.

09.07.2026 Reference to KBCN1890 added

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Life Cycle Assessment for multiple buildings within a single assessment (GN20 – Section 6) - KBCN1835

Where a BREEAM assessment includes multiple buildings on the same site with a single, over-arching function, in accordance with Section 6 of GN20 (e.g. a principal building with one or more ancillary or supporting buildings), and where these are not classified as ‘similar buildings’, each building must be assessed and reported separately within the LCA. A single aggregated result for the whole site is not sufficient on its own, even where a single coordinated LCA model is used. Shared elements (e.g. substructure, external works, or building services serving multiple buildings) may be apportioned between buildings using a reasonable and transparent method (e.g. by gross internal area or other appropriate project-specific metric), in line with recognised industry approaches. For the purposes of BREEAM benchmarking under Mat 01: • The results submitted to the platform must represent a single building, not a combined site-wide result. • Where multiple buildings are included within an assessment, benchmarking (in kgCO₂e/m²) must be based on the principal building. Where no clear principal building exists, the largest building should be used. Full evidence must be provided to demonstrate: • That all buildings within scope are included, with individual LCAs completed for each building, and • How results have been separated and, where relevant, how shared elements have been allocated.

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Rationale: Industry standards such as RICS guidance and the UK Net Zero Carbon Buildings Standard define assessment boundaries at the building (asset) level, while allowing aggregation at project level only where individual building results are also reported. Requiring building-level results ensures consistency with industry practice, maintains comparability with BREEAM benchmarks, and avoids distortion where multiple buildings are combined into a single result.

Note: This approach applies until further platform functionality is available to support multi-building submissions directly.

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Life Cycle Assessment – Similar buildings with identical design (GN20 Section 4) – Representative LCA approach - KBCN1890

Where multiple buildings are substantially identical in design, construction and specification, and any differences are limited to scale, a representative LCA approach may be used instead of completing a full LCA for every building. Where buildings are not substantially identical, see KBCN1834. For the purposes of BREEAM benchmarking under Mat01:

• A representative LCA and a single options appraisal may be applied across all buildings, provided that all specifications (including scoped elements) are consistent and carbon reduction measures are specification-driven rather than scale-dependent.
• Robust justification and supporting evidence must be provided to confirm representativeness. The representative model should normally be the largest, most carbon-intensive, or otherwise demonstrably representative building within the development.
• Results must be expressed in normalised form (e.g. kgCO₂e/m²) and demonstrated to be applicable across all units, with any variation in outcomes shown to be not materially significant (e.g. within ±10%).
• Shared elements (e.g. substructure, external works, or building services serving multiple buildings) may be apportioned between buildings using a reasonable and transparent method (e.g. by gross internal area or other appropriate project-specific metric), in line with recognised industry approaches.

Demonstrating representativeness does not require full LCAs for additional units; proportionate methods such as parametric scaling of quantities or elemental intensity comparisons may be used to evidence that variation in normalised results is not materially significant. Where there is uncertainty regarding representativeness, a secondary check model for an additional unit is recommended to verify consistency of results.

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Rationale: The representative LCA approach provides a proportionate means of assessing developments containing multiple highly similar buildings while maintaining confidence that reported results are representative of individual building performance. It is intended as a limited exception to the standard requirement for building-specific assessment.

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