Mainer Associates have successfully driven a landmark reform in how BREEAM Design Stage Assessments are undertaken - a transformation that marks one of the most significant evolutions in the scheme’s history.

After nearly five years of sustained collaboration and lobbying with the Building Research Establishment (BRE), their expertise and advocacy have culminated in the acknowledgement of the importance of the strategy tabled by Mainer, with the release of BREEAM Guidance Note 55 (GN55): Contractual Clauses, which fundamentally reshapes the way evidence is produced and verified during the design and procurement phases.

What has changed?

Historically, many BREEAM credits could only be demonstrated once design information was finalised or contractors were in place. This created challenges for early submissions - particularly where BREEAM ratings were tied to funding, planning, or procurement milestones.

GN55 changes this paradigm by enabling assessors to use contractual clauses and performance commitments as valid evidence at the Design Stage, as long as these are contractually bound.

This means sustainability requirements are embedded directly into construction contracts, ensuring that BREEAM obligations are clearly defined, allocated, and contractually enforceable even before works commence.

Key updates introduced in GN55 include:

Early-Stage Submissions
Design Stage assessments, even under a D&B contract, can now be submitted at RIBA Stage 3 or 4, provided robust contractual evidence is in place to demonstrate accountability.
Contractual Evidence Framework
BRE now explicitly recognises BREEAM-specific contractual clauses as acceptable forms of evidence for many credits across all categories.
Defined Roles and Responsibilities
Clauses must now specify who is responsible, what actions will be taken, and how compliance will be evidenced, giving BREEAM assessors and BRE auditors confidence the correct process has been followed.
Alignment with Procurement Routes
The guidance differentiates between traditional and design-and-build contracts, allowing flexibility where designs are still developing during Stage 4 & 5, while maintaining rigour in later-stage verification.
Integration with the Building Safety Act
GN55 embeds BREEAM within the ‘Golden Thread’ of information required by the Building Safety Act, ensuring sustainability criteria are captured, tracked, and evidenced throughout the project lifecycle.
Clarity and Consistency
Following detail provided by Mainer, BRE have provided a detailed credit-by-credit table within GN55 which specifies exactly which issues can be evidenced using contractual clauses, and where additional documentation (drawings, calculations, etc.) remains necessary.

Together, these changes establish a more transparent, auditable link between design intent and construction delivery - closing the gap that previously existed between sustainability targets and on-site implementation.

The Building Safety Act 2022 is a UK law designed to improve building safety, particularly in higher-risk buildings, and to ensure the safety of people in and around buildings.

There are three gateways in the Building Safety Act:

The Full Planning Application whereby a package of usually Stage 3 information is provided
Gateway 2 must be submitted before start on site, and
Gateway 3 preoccupation.

A comprehensive package of building information is supplied to the Health and Safety Executive (HQE), at each of the Gateways and any deviation between the Gateways must be evidenced and rationale for deviations provided.

This is the ‘Golden Thread’, and it is effectively a master specification/package of building information where any changes in products or design, as is commonplace in design and build contracts particularly, must be logged, properly evidenced, and signed off.

The Golden Thread of information could include items to ensure BREEAM compliance, at the same time as compliance with the Building Safety Act. However, it is not necessary to submit the Golden Thread information to achieve compliance with specific BREEAM credits.

Source: GN55 BREEAM contractual clauses – Knowledge Base

Why this matters

By formalising the use of contractual clauses, BREEAM has evolved from a design review tool into a procurement-integrated compliance framework. This not only enhances accountability but also aligns sustainability assessment with legal, commercial, and safety governance structures.

For clients and contractors, this means greater certainty and reduced risk when targeting BREEAM ratings. For assessors, it provides clearer pathways to early-stage certification and a more robust audit trail during project delivery.

Mainer Associates’ role

With over 45 years of collective experience in BREEAM, dating back to BREEAM 2006, Mainer Associates have long been a trusted voice in sustainable construction. From pioneering Post Construction Reviews to guiding the adoption of Green Leases, our team has consistently influenced how the built environment measures, manages, and evidences sustainability.

This latest milestone is a testament to the firm’s independent expertise, persistence, and collaboration. By shaping BRE’s approach to contractual evidence, Mainer Associates have ensured that BREEAM now moves in step with industry regulation and modern procurement practices - strengthening the integrity and delivery of sustainability commitments across the sector.

A stronger, more accountable future for BREEAM

This evolution marks more than an administrative update - it’s a fundamental shift in philosophy. By embedding sustainability actions into legally binding documents, the BREEAM process becomes both proactive and enforceable, ensuring that environmental and safety ambitions survive the transition from design to construction.

Through their leadership and persistence, Mainer Associates have helped secure a future where BREEAM isn’t just an assessment tool, but a core part of the contractual and operational DNA of sustainable development.

To talk us about BREEAM on your next project get in touch