06 - Materials - BREEAM Knowledge Base

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.

Definition – Reused in situ - KBCN1902

Definition A material qualifies as reused in situ where it meets all of the following:

It is removed from its original position or original application within the building.
It undergoes no more than minor processing that does not alter its fundamental nature (e.g. cleaning, cutting, fixing to other materials).
It is reinstalled in a different position or a different application within the building (or reused elsewhere within the project).

Exclusion Materials that remain in their original location and application throughout the works, including where they undergo minor processing such as cleaning, repair or redecoration, are considered as retained. These must be excluded from the Mat 03 calculator.

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

Evidence requirements – responsible sourcing of materials at post-construction - KBCN1599

Whilst the UK BREEAM manuals are less prescriptive in the evidential requirements to allow flexibility, to ensure consistency across the schemes, it is expected that robust evidence should be provided to verify the source of any certified materials and how the assessor has confirmed the products and manufacturers used. Evidence supplied at post construction stage must reflect the completed building and confirm the responsibly sourced materials that have been procured and installed on the project. Supporting documentation is required to validate letters of confirmation or schedules of materials. Evidence provided could include proof of purchase, for example, invoices, delivery tickets, purchase orders or correspondence from suppliers. This may be an example for each material sourced, rather than every delivery ticket for instance. Alternatively, evidence of the use of the responsibly sourced materials may include as-built drawings, O&M documentation or site photographs.

30-Oct-2025 - Applicable to HQM V6 and UKNCR V6.1

GN18 BREEAM Recognised Responsible Sourcing Certification Schemes and BREEAM Scheme Applicability - KBCN0723

Latest version: v3.7, May 2023 BREEAM awards credits for responsibly sourcing construction products (typically under the Mat 03 issue) to encourage responsible product specification and procurement in construction. To achieve these credits, applicable specified products (as listed in the relevant technical manual) must be covered by an Environmental Management System (EMS) or a responsible sourcing certification scheme (RSCS) recognised by BREEAM. Guidance Note 18 (GN18) lists the responsible sourcing certifications schemes recognised by BREEAM along with the relevant summary scores to be used in BREEAM assessments. Download Guidance Note 18 Download Guidance Note 18 v2.0 (licensed assessors only - optional for projects registered prior to release of v3.0 in September 2016) View all Guidance Notes on BREEAM Projects (licensed assessors only)

21-Jul-2026 - Applicable to NC V6, NC V7, RFO V7

GN24 Demonstrating compliance with responsible sourcing requirements in BREEAM - KBCN0721

Latest version: v1.2, July 2026 Guidance Note 24 (GN24) provides additional guidance to assessors and specifiers on demonstrating compliance with the 'Measuring responsible sourcing' criteria in BREEAM (typically in Mat 03). It should be read in conjunction with the Technical Manual for the relevant assessment scheme. It covers:

How to deal with constituent products/materials including those with certification that is different from the overall product.
The precision required in estimating quantities:
- For the cut-off volume
- Of products/materials in the building (Route 2 only)
- Of different material categories in products/materials.
An example Route 2 calculation.
‘Broken chain’ situations.
How to treat building services.

Download Guidance Note 24 View all Guidance Notes on BREEAM Projects (licensed assessors only)

15-Jul-2026 - Updated version released (v1.2)

GN51 Guidance on LCA and embodied carbon calculations for Mat 01 in BREEAM V7 - KBCN1684

Latest version: v1.0, July 2026 Guidance Note 51 (GN51) provides supporting information for the new Mat 01 criteria in BREEAM V7. Its development is driven by the introduction of new credit allocation criteria for Mat 01. While the core principles of measuring and reporting a building's environmental performance through life cycle assessment (LCA) and benchmarking were introduced in BREEAM UK New Construction 2018, significant revisions have been made to align the criteria across BREEAM schemes and with existing LCA frameworks and methodologies. This guidance note explains the primary methodology for Mat 01, including minimum requirements and the scope of the LCA. Download Guidance Note 51 View all Guidance Notes on BREEAM Projects (licensed assessors only)

15-Jul-2026 - Updated version released (v1.0)

Independent third party – clarification on the definition - KBCN1805

For the purposes of BREEAM, sister companies or parent companies cannot be considered as third parties. To be classed as an independent third party, there must be no professional connection or relationship between the LCA consultant/energy assessor, or their company, and the verification body. The third-party verifier must be independent of the LCA or energy assessor and demonstrate impartiality (for general principles, see ISO 17029). To qualify as a third party, the verifier must belong to an organisation not involved in the project and must not provide advice to the project, as this could compromise their impartiality during verification.

Legally harvested and traded timber – Examples - KBCN0956

The following examples are considered compliant for BREEAM: Legally harvested:

Evidence of compliance with the UK government Timber Procurement Policy (see here, timber bought inside the UK only)
FSC, PEFC, SFI or GiB certification
Evidence of compliance with the EUTR (timber bought inside the EU only)
Risk assessment/due diligence documentation demonstrating a low risk of non-compliance with the ‘legally harvested’ requirements given in the manual.

Legally traded:

Evidence of compliance with the UK government Timber Procurement Policy (see here, timber bought inside the UK only)
FSC, PEFC, SFI or GiB certification
Risk assessment/due diligence documentation demonstrating a low risk of non-compliance with the ‘legally traded’ requirements given in the manual.

04-Dec-2025 - Examples updated to include Grown in Britain (GiB) certification. Previous reference to 'CPET' clarified as 'UK government Timber Procurement Policy'.
KBCN applied more widely to all relevant scheme issues in BREEAM and HQM

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.

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

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.

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.

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.

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.

Meeting the minimum standard requirement – compliance when chain of custody is broken - KBCN1816

Where there is a broken chain in the last link between the purchase and delivery of certified timber from the supplier and the forwarding distribution of the timber to the site under assessment, such as where the timber has been delivered to a subcontractor or fabricator’s premises instead of direct to site (e.g. as part of a bulk order or where limited storage is available on site), compliance can still be achieved if a documented risk assessment confirms that there is low risk of mixing or substitution of certified and non-certified timber. Ways to demonstrate compliance: A. Verification that the subcontractor or fabricator only purchases and uses certified timber. There must be robust mechanisms in place to verify that all timber materials purchased and delivered originate from sustainably managed sources. This includes maintaining documented timber procurement policies and procedures that mandate certified timber orders and delivery checks. Comprehensive supplier details should be readily accessible for review upon request to demonstrate that all timber is certified. B. Where non-certified timber is handled/stored or sourced, that there are robust control measures in place to prevent any substitution or mixing of certified and non-certified timber at every stage of the process. Documentation demonstrating compliance should be maintained and made available upon request. Examples of appropriate control measures are listed below:

Control	Evidence required
Purchasing records	All purchase orders, requisition notes, and contracts must explicitly specify the product details and confirm that materials are to originate from legal and sustainable sources.
Segregated storage of timber	Site layout map, stock control processes and records to confirm that certified timber is stored away from non-certified timber.
Segregated delivery of timber to site	- All timber must be thoroughly inspected and verified before shipment to confirm that it is correctly marked/labelled as FSC/PEFC-certified. - Delivery notes must be accurately maintained. - A second-party verification process to check tickets and stock, must be carried out upon site delivery to confirm certified status of timber.
Documentation	Comprehensive documentation must enable independent assessors to trace any timber back to its sustainable source. This includes maintaining purchase records, goods-inward notices, stock records, and sales documentation such as orders and invoices.

The above is guidance and should not replace any local or national requirements for the sourcing of legally traded and harvested timber.

1 June 2026 - Updated to apply to New Construction and RFO Schemes

New Construction / International / V7 /

06 - Materials

Bamboo, cork and other non-timber forest products – Responsible sourcing - KBCN1768