M&E Design Responsibility: Performance vs Prescriptive, with a Free Matrix Template

What is design responsibility in building services, and why is it contested?

Design responsibility is the written allocation of each design activity for each building services system between the consultant, the contractor and any specialists. It is contested because services design is usually shared and the allocation is often left implicit.

Building services is the discipline where design is most often shared. A typical project has a consultant who designs the scheme and a contractor who selects plant, sizes distribution within the scheme, produces installation drawings and commissions. How much of each is the consultant's and how much the contractor's varies by system, by procurement route and by appointment. Where the allocation is not written down it is argued from memory, usually after a clash or a late plant change.

Three questions need an answer for every system. Who leads each design activity? What does that party need from others before starting? What must it return, and to whom? A fourth sits at the edge of each system: where does this design stop and another begin? The answers belong in one document, the design responsibility matrix, and they should be consistent with the specification, the schedules and the contract.

Why it matters more now

Designers in England have duties under Part 2A of the Building Regulations 2010, inserted by SI 2023/911. A designer must plan, manage and monitor design work so that it complies, and the allocation of design between parties is part of that planning. On higher-risk buildings the allocation also feeds the golden thread: if the record cannot show who designed a smoke control system or a sprinkler installation, it cannot show who was competent to. Gateway 2 and the Golden Thread for Building Services Engineers covers the records. The architect's equivalent of this document is covered in the architect's design responsibility matrix guide; this guide is the services engineer's version.

If a services system appears in the specification but not in the matrix, nobody has agreed to design it.

How does BSRIA BG 6 allocate design responsibility?

BG 6/2018 provides proformas that allocate design activities by stage to project parties as lead, support or review, a spreadsheet that allocates deliverables, and definitions of drawings and models.

BSRIA's Design Framework for Building Services is the standard UK reference for this allocation. The edition referred to here is the fifth, BG 6/2018. Check the BSRIA listing for the current edition before relying on it. It is a paid publication, and the BSRIA product page lists its contents. The summary below describes how it is organised, without reproducing it.

How the roles work

BG 6/2018 lets each design activity be allocated to project parties as Lead, Support or Review. BSRIA's own answer to a customer question notes that the guide does not itself define the three roles, and offers working definitions: the lead is the party responsible for carrying out the activity, support parties provide input to the lead, and review parties review the activity and give feedback to another defined party such as the client. Whatever definitions a project adopts, write them into the appointment and the specification so that everyone reads the letters the same way.

Stages and editions

BSRIA states that the proformas in the fifth edition follow the project stages of the RIBA Plan of Work 2013, and provides separate notes for use with the RIBA Plan of Work 2020. The fifth edition also combined the fourth edition's proformas 3a and 3b into a single proforma 3 covering the whole of RIBA Stage 3, and 4a, 4b and 4c into a single proforma 4 covering the whole of Stage 4, and deleted proforma 0. A project working to the RIBA Plan of Work 2020 should record which stage naming it uses and how BG 6's stages map to it. The mapping is simple, but it needs to be written down.

BG 6 is a framework and an allocation tool, not a contract term. It supports contract documents by providing a shared vocabulary, and the appointment and contract govern what the allocation means. If BG 6 is to be the agreed basis, say so in the appointment, and name the edition.

Who designs what: the consultant or the specialist contractor?

Each system falls into one of three patterns: the consultant completes the design, the design is shared, or the contractor completes it. The pattern sets the clause type, the inputs the consultant provides and the returns the contractor must make.

For each building services system, someone completes the design. The question is who, and with what information from the other party. Three patterns cover most projects.

What each pattern obliges the consultant to provide

Where the contractor completes or shares the design, the consultant's duty is to give the contractor enough information to design the right thing. For services, that usually means design conditions (internal and external temperatures, occupancy, ventilation rates), loads and capacities that the design must carry, plant space and routes available, resilience and redundancy requirements, standards and their editions, controls intent, interfaces with other systems and any constraints from the fire strategy. A performance clause that omits these is a request to guess.

What each pattern obliges the contractor to return

The returns are the other half of the allocation: calculations, plant selections with performance data, installation drawings, controls software descriptions, test and commissioning results, and, on projects with golden thread requirements, evidence that can be filed against the relevant clause. Say when each is due. A selection that arrives after the order is placed cannot be reviewed in any real sense. The guide to contractor-designed portions and How to Write an M&E Specification set out the clause structure.

Review is not design transfer

When the consultant reviews a contractor's submission, the purpose is to check it against the requirements issued. It is not a transfer of the design. Review comments that go beyond that purpose can be read as design instructions, which blurs the allocation. State the purpose and the extent of review in the specification, use the same words on the review stamp and keep the review period in the programme. The detailed effect depends on the appointment and the contract, so take advice on the wording.

How do design stages line up with the RIBA stages?

For services, the allocation matters most between Stages 2 and 5, with the key handover at Stage 4 when specialist contractors complete designed portions after award.

The RIBA Plan of Work 2020 has eight stages, from Stage 0 (Strategic Definition) to Stage 7 (Use). For building services design, Stages 2 to 5 are where the allocation matters. The RIBA Plan of Work 2020 overview notes that procurement strategy influences when building systems will be designed and may require Stage 4 to be undertaken in two parts, with specialist subcontractors designing building systems after the building contract is awarded. Services packages are the usual example.

The matrix should be reviewed at each handover point: at the end of Stage 3, before the tender issue, on appointment of the specialist and at handover. Each review compares the matrix with the specification, the schedules and the contract documents. The RIBA Stage 4 guide shows where the matrix sits in technical design, and commissioning, soft landings and O&M specification covers the final rows.

What does a free M&E design responsibility matrix template look like?

A usable template has one row per system and columns for the consultant's and contractor's roles, the information type, the inputs provided, the returns required and the interface owner. Copy the table below into a spreadsheet and adapt it.

The matrix below is a short template a practice can copy into a spreadsheet. It is not a BSRIA document, and it does not replace BG 6 where BG 6 is the agreed basis. The rows are illustrative: replace them with the project's own systems and tag codes. Roles use the lead, support and review letters: L, S, R.

How to fill in each column

System. Use the tag or code that appears on the drawings, schedules and specification. A matrix with its own system names drifts from the other documents within weeks.

Consultant and contractor roles. Name one lead per row and per stage. “Consultant and contractor” in a lead cell means nobody has decided. Where responsibility genuinely splits, split the row.

Information type. Prescriptive, performance or a stated mix. This is the column that links the matrix to the clause, and the one most often left out.

Inputs and returns. List what the design team provides and what the contractor returns, with dates. A return with no date has no review.

Interface owner. Name the party who owns each junction: plant room to structure, riser to fire strategy, ceiling void to architect.

A checklist for keeping the matrix honest

• ✓One named owner for the matrix, recorded in the quality plan.
• ✓Every system row has a matching clause, and every clause has a matching row.
• ✓Every performance row lists inputs and returns with dates.
• ✓The contract documents identify the same contractor-designed portions as the matrix.
• ✓Every interface names the party that owns the junction.
• ✓The stage naming used in the matrix is stated, and BG 6 or other stage proformas are mapped to it.
• ✓The matrix is revised at each handover point and the revision is dated.

For architects who need the same table with the architectural elements, see the architect's guide and template. On a higher-risk building the services rows should also be traceable from the fire and emergency file, so that the record shows who designed each fire safety system.

Questions engineers ask about M&E design responsibility

What is an M&E design responsibility matrix?

A table that records, for each building services system, who leads the design at each stage, who supports and who reviews, what information the design team provides, what the contractor returns, and who owns each interface. It turns the allocation of design between consultant and specialist contractor into a written record that the specification and contract documents can match.

What is BSRIA BG 6?

BG 6 is BSRIA's Design Framework for Building Services. The fifth edition, BG 6/2018, was published in June 2018. It provides proformas for allocating design activities by project stage, a spreadsheet for allocating system-specific deliverables, and definitions for drawings and models, to help consultants, contractors and clients agree the extent of each party's design.

Does BG 6 work with the RIBA Plan of Work 2020?

BSRIA states that the proformas in BG 6/2018 follow the stages of the RIBA Plan of Work 2013 and provides separate notes on using the guide with the RIBA Plan of Work 2020. Check those notes and the project's own stage definitions before attaching the proformas to an appointment or a specification.

When should a services system be specified by performance?

When the contractor completes the design. The engineer states the design inputs, the performance required, the standards and the proof, and the contractor designs the solution and submits it for review. Choose per system, and make sure the clause, the schedules and the matrix all say the same thing.

Can the consultant be responsible for a contractor-designed portion?

The consultant is normally responsible for the information and the performance requirements issued, and for any review role defined in the appointment. The contractor is responsible for the design of the portion. Reviewing a submission does not transfer design responsibility, and the wording of the appointment and the contract governs the detail.

Is there a free template?

This guide includes an illustrative matrix that practices can copy into a spreadsheet and adapt. It is not a BSRIA document, and it does not replace BG 6 where BG 6 is the agreed basis. The columns are system, consultant role, contractor role, information type, inputs provided, returns required and interface owner.

Where Avoice fits

A responsibility matrix is only useful if the specification says the same thing, and that is a comparison task.

Avoice writes building services specifications alongside architectural ones. The pre-issue Technical Review compares the specification with the schedules and drawings, which catches a clause that is prescriptive where the matrix says the contractor designs, or a scheduled system with no clause behind it. Practice Rules can require that every performance clause states the result, the standard and the proof, and the clause library can hold the practice's standard wording for design inputs and required returns, so they are not left to the author's memory.

Construction Admin tracks submittals against the contractor-designed portions after award, and spec change tracking records changes to requirements. The engineer allocates design, and the contract determines what the allocation means. Software holds the structure and compares the documents. For the architect's view of the same matrix, see Design Responsibility Matrix: A Guide and Template for UK Architects.