The Building Services Design Process

A Walkthrough of the RIBA Plan of Work

Designing and delivering building services for a building is a complex, multi-stage process requiring collaboration among architects, engineers, contractors, and clients. The RIBA Plan of Work is the standard framework used in the UK and internationally to structure this process.

This article provides a walkthrough of the RIBA Plan of Work from a building services engineer’s perspective, explaining how MEP services evolve through each stage.

What is the RIBA Plan of Work?

The RIBA Plan of Work is a framework that divides the building design and construction process into distinct stages. Each stage has specific objectives, deliverables, and activities. The Plan of Work is used to organize project teams, manage risk, and communicate progress.

The current RIBA Plan of Work comprises eight stages:

1. Stage 0: Strategic Definition
2. Stage 1: Preparation and Briefing
3. Stage 2: Concept Design
4. Stage 3: Spatial Coordination
5. Stage 4: Technical Design
6. Stage 5: Manufacturing and Construction
7. Stage 6: Handover and Close Out
8. Stage 7: In Use

Stage 0: Strategic Definition

Objective: Establish the client’s business case, strategic requirements, and project feasibility.

Building Services Input: During Stage 0, building services engineers assess site constraints and major utility connections. They identify the likely capacity of electrical, gas, and water utilities and any limitations that could affect the project scope. They provide high-level cost estimates and sustainability targets, such as BREEAM or LEED ratings.

Key Activities:

• Site assessment for utilities
• Identification of high-level performance targets
• Feasibility studies
• Preliminary cost planning
• Risk identification

Deliverables: Site utility assessment, preliminary sustainability targets, feasibility report.

Stage 1: Preparation and Briefing

Objective: Develop the project brief, define functions of the building, and establish the project team.

Building Services Input: Building services engineers help the client articulate their requirements. They identify operational needs, such as:

• What activities will the building host?
• What are the comfort requirements?
• What systems are critical?
• How reliable must the systems be?
• What is the budget?

Engineers consider future flexibility and expansion possibilities. They also study local regulations and standards.

Key Activities:

• Brief-taking and user interviews
• Consideration of likely loadings and service requirements
• Preliminary design assumptions
• Identification of regulatory framework
• Feasibility studies

Deliverables: MEP design brief, preliminary system recommendations, regulatory compliance report.

Stage 2: Concept Design

Objective: Develop the architectural concept and propose building services strategies.

Building Services Input: At Stage 2, building services engineers develop a concept for the services. They work with the architectural team to understand the building form and how it affects the services strategy.

Key concept design decisions are made regarding:

• Type of heating/cooling system (e.g., VRF, chilled water, heat pumps)
• Type of ventilation (natural, mechanical, mixed-mode)
• Main electrical distribution strategy
• Lighting approach
• Plumbing/drainage routing
• Renewable energy integration
• Sustainability and energy efficiency strategies

Early BIM modeling often begins at this stage. High-level system schematics and load estimates are produced.

Key Activities:

• Concept development for each service
• Initial load calculations (heating/cooling/electrical)
• Major equipment selection
• Spatial coordination with architecture
• Sustainability strategy
• Cost planning and risk assessment

Deliverables: Concept design report, high-level schematics, preliminary equipment list, energy strategy.

Stage 3: Spatial Coordination

Objective: Develop the design in more detail, coordinating spatial requirements between disciplines.

Building Services Input: Stage 3 is where building services engineers coordinate with other disciplines to ensure designs are spatially feasible. This is often the most critical stage for engineers because space constraints become apparent.

The building services engineer develops detailed layouts for mechanical, electrical, and plumbing systems and participates in clash detection reviews. They adjust service routes to avoid structural elements and architectural features. They ensure access for maintenance and future modification.

BIM is essential here. Engineers use the model to coordinate ductwork, pipework, cable trays, and equipment.

Key Activities:

• Detailed service layouts
• Clash detection and resolution
• Coordination with structural and architectural design
• Equipment sizing and selection
• Detailed cost planning
• Risk assessment and mitigation

Deliverables: Coordinated MEP model, updated schematics, equipment schedules, updated cost plan.

Stage 4: Technical Design

Objective: Prepare detailed technical designs and specifications suitable for construction and regulatory approval.

Building Services Input: At Stage 4, building services engineers produce the final technical design. This includes:

• Fully defined system designs
• Equipment specifications
• Sizing and selection of all equipment
• Detailed drawings and schematics
• Construction specifications
• Control system design
• Coordination with other disciplines

The engineer also refines the energy model and prepares all documentation required for statutory approvals.

Key Activities:

• Detailed equipment sizing
• Preparation of drawings and specifications
• Tendering documentation
• Building regulation submissions
• Fire engineering and safety strategy
• Acoustic design
• Sustainability modeling

Deliverables: Construction drawings, specifications, building regulation submissions, tendering documents.

Stage 5: Manufacturing and Construction

Objective: Oversee the construction of the building, ensuring compliance with design intent.

Building Services Input: During Stage 5, building services engineers provide support to the construction team. They respond to RFIs (Requests for Information), review contractor submissions, and attend site meetings. They conduct site inspections to ensure quality, compliance, and progress.

Building services engineers also manage design changes that occur during construction, updating the design accordingly. They ensure that interfaces between building services and construction are properly coordinated.

Key Activities:

• Site inspections
• RFI responses
• Review of contractor submissions
• Change management
• Quality assurance
• Coordination with site teams

Deliverables: Site inspection reports, change orders, updated record drawings.

Stage 6: Handover and Close Out

Objective: Hand over the completed building to the client, including commissioning and training.

Building Services Input: Stage 6 is critical for building services. The engineer oversees commissioning and testing of all building services systems, verifying performance against design targets. They ensure all systems are tested, adjusted, and balanced.

They prepare operation and maintenance manuals, provide training to building operators, and assist with the final handover.

Key Activities:

• Commissioning
• Testing, adjusting, and balancing
• Preparation of O&M documentation
• End-user training
• As-built drawings
• Final handover

Deliverables: Commissioning reports, O&M manuals, training records, as-built documentation.

Stage 7: In Use

Objective: Monitor performance of the building after occupation and improve operational efficiency.

Building Services Input: In Stage 7, building services engineers provide support to building operators. They may monitor energy consumption, compare actual vs. predicted performance, and investigate building management system (BMS) alarms.

Post-occupancy evaluation is becoming increasingly common. Engineers use this feedback to improve future designs.

Key Activities:

• Post-occupancy evaluation
• BMS optimization
• Fault diagnostics
• Feedback to design team
• Ongoing support

Deliverables: Post-occupancy evaluation reports, BMS monitoring data, recommendations for improvement.

Conclusion

The RIBA Plan of Work provides a robust framework for managing the design and construction of building services. By following this process, building services engineers ensure that systems are thoroughly designed, coordinated, installed, tested, and commissioned.

The process requires collaboration, communication, and careful attention to detail at every stage. When done well, it results in buildings that are comfortable, safe, efficient, and durable.

For building services engineers, the RIBA Plan of Work provides structure and clarity in what is otherwise a complex and demanding profession.

The RIBA plan of work overview can be found here: https://www.riba.org/media/syneeeto/2020ribaplanofworkoverviewpdf.pdf