WYRM MEP

1.1 General Design Standards

The mechanical, electrical and public health services shall be designed and installed in accordance with, but not limited to, the current editions of the following standards, codes of practice and statutory instruments, together with all relevant amendments:

• The Building Regulations (England) and all Approved Documents, in particular Part L (Conservation of fuel and power), Part F (Ventilation), Part M (Access) and Part B (Fire safety)
• BS 7671 — Requirements for Electrical Installations, IET Wiring Regulations, 18th Edition, including all amendments
• CIBSE Guides A, B, C, F, H, K and M, and the relevant CIBSE Lighting Guides / SLL Code for Lighting
• BSRIA and BESA (formerly HVCA) guidance, including DW/144 for ductwork and BG 2 for commissioning
• BS 5839 (fire detection & alarm), BS 5266 (emergency lighting) and BS EN 62305 (lightning protection)
• BS 8558 and the Water Supply (Water Fittings) Regulations, HSG274 / HSE L8 (control of legionella)
• The Gas Safety (Installation and Use) Regulations and IGEM standards where gas services are provided

1.2 Mechanical & Public Health Design Criteria

The mechanical and public health services shall be designed to achieve the internal design conditions set out below. Where a project-specific value is not yet confirmed it is shown as 'TBC' and shall be developed against the employer's brief and the relevant CIBSE / BCO guidance.

1.2.1 Internal Design Conditions

1.2.2 Fabric U-Values & Ventilation Rates

Fabric thermal performance (external wall, roof, floor, glazing and spandrel U-values, G-value and air permeability) and fresh-air ventilation rates shall be coordinated with the architectural fabric specification and Part L / Part F, and confirmed in the design criteria schedule. Fresh air shall be provided at not less than the rate required by BS EN 16798-1 / CIBSE Guide A for the occupancy density adopted.

GAP: Project design values (internal temperatures, U-values, G-value, air permeability, fresh-air rate, occupancy density and casual gains) to be authored from the project brief and populated from the impact/energy calc run via cross-check.

1.3 Electrical Services Design Criteria

The electrical services shall be designed to the maintained illuminance, small-power provision, diversity and resilience criteria appropriate to each space, in accordance with BS 7671, the SLL Code for Lighting and BS EN 12464-1. Maximum demand shall be established by a diversified load assessment; final circuit design shall verify voltage drop, earth-fault loop impedance and discrimination.

GAP: Project electrical design values (maintained lux by space, small-power W/m², maximum demand, diversity factors and resilience/redundancy strategy) to be authored and cross-checked against the electrical load calc.

1.4 Acoustic Criteria

Building-services noise shall not exceed the indoor ambient noise levels (NR / dB(A)) agreed with the project acoustician for each space type. Plant, ductwork, pipework and terminal devices shall be selected, mounted on anti-vibration mounts and attenuated as necessary to meet the agreed criteria, including break-out and cross-talk limits between acoustically-sensitive spaces.

GAP: Project acoustic criteria (NR levels per space, plant break-out limits) to be confirmed with the acoustician.

1.5 Sustainability & BREEAM

The services shall be designed to support the project's sustainability targets, including the targeted BREEAM rating, the operational energy / carbon strategy and any Part L notional-building improvement. Energy metering, low-carbon heat generation, efficient plant selection and controls shall be provided to secure the relevant Ene, Wat and Hea credits.

GAP: Targeted BREEAM rating, energy/carbon targets and specific credits to be confirmed with the sustainability consultant.

1.6 Key Risks & Assumptions

The design has been developed on the assumptions listed below, which require confirmation by the employer and design team. Any departure will require the affected systems to be reviewed.

• Incoming utility capacities (electrical, water, gas, telecoms) are available at the positions and ratings assumed and will be confirmed by the relevant statutory undertaker.
• Structural provision (loadings, builder's work openings, plant lifting/replacement routes) is available as coordinated with the structural engineer and architect.
• The occupancy, operating hours and internal gains are as adopted in the design criteria.

GAP: Project-specific risks, assumptions and outstanding information to be maintained on the live design risk register.

1.7 Contractor's Design Responsibilities

This specification describes the design intent and performance requirements. The Contractor is responsible for completing the detailed design of the Contractor's Designed Portion (CDP) items, for producing installation and coordination drawings, and for the selection, supply, installation, testing and commissioning of all plant and equipment to achieve the specified performance. Where an item is marked 'CDP' the Contractor shall develop the design in accordance with this specification, the Materials & Workmanship specification and all statutory requirements.

2.1 Scope of Utility Works

This section describes the incoming statutory utility supplies serving the development and the associated diversions of existing services. The Contractor shall liaise with each statutory undertaker to confirm points of connection, capacities, lead-in times and metering arrangements, and shall include for all builder's work, ducts, trenches, chambers and connection charges.

2.2 Incoming Electrical Supply

A new electrical supply shall be provided from the Distribution Network Operator (DNO) to serve the estimated maximum demand of the building. The supply arrangement (LV or HV, single or dual feed, substation provision and metering position) shall be agreed with the DNO and coordinated with the intake and switchroom layouts. Where an HV supply is adopted, packaged substations shall be provided with the resilience required by the design brief.

GAP: Estimated maximum demand, supply voltage/arrangement (LV/HV), substation rating and DNO reference to be confirmed and cross-checked against the electrical load calc.

2.3 Incoming Water Supply

A new metered cold water connection shall be provided from the local water authority infrastructure, entering the building at high level within the plant/intake area and incorporating an isolation valve, non-return valve (verifiable backflow prevention to the appropriate fluid category) and the authority revenue meter, in accordance with the Water Supply (Water Fittings) Regulations and BS 8558.

GAP: Incoming main size, pressure/flow available and boosted-storage requirement to be confirmed with the water authority and cross-checked against the public-health demand calc.

2.4 Incoming Gas Supply

Where gas services are required, a new supply shall be provided from the gas transporter to a meter installation sized for the connected load, with primary meter, isolation and, where applicable, a gas proving / solenoid safety shut-off interlock in accordance with the Gas Safety (Installation and Use) Regulations and IGEM standards. Where the project is all-electric this clause is not used.

GAP: Confirm whether a gas supply is required; if so, connected load and meter rating to be confirmed with the gas transporter.

2.5 Telecommunications & Incoming Data

Diverse containment routes and entry positions shall be provided for the incoming telecommunications and data service providers, terminating in the main communications/intake room. Duct provision, draw-pits and building entry shall be coordinated with the providers' requirements.

GAP: Service providers, number of incoming routes and comms-room position to be confirmed with the client's IT strategy.

2.6 Existing Services & Diversions

Existing utilities affected by the works shall be identified from statutory records and site survey, and diverted or disconnected as necessary in agreement with the relevant undertaker. The Contractor shall maintain supplies to any retained areas and sequence diversions to suit the construction programme.

• Electricity diversions coordinated with the DNO.
• Water and gas diversions coordinated with the respective undertakers.
• Telecoms diversions coordinated with the service providers.

3.1 Scope of Works

The Contractor is to design (CDP), supply, install, test and commission complete mechanical services comprising heating and cooling generation and distribution, air handling and ventilation, and the associated pipework, ductwork, insulation, pumps, valves and controls interfaces, to achieve the design criteria of Section 1 and the performance described in this section. All work shall comply with the Materials & Workmanship specification.

Materials & Workmanship Specification (Mechanical)

3.2 Heating & Cooling Generation

Low-carbon heat and cooling shall be generated by high-efficiency electric heat pumps (air source and/or water source as appropriate to the site), sized for the peak heating and cooling loads with the resilience required by the brief. Low temperature hot water (LTHW) and chilled water (CHW) shall be distributed by variable-speed pumps through a fully-insulated, pressure-tested pipework network with pressurisation, dosing and thermal balancing.

3.2.1 Distribution Temperatures

Flow/return temperatures shall be selected to maximise heat-pump efficiency (typically low-flow LTHW and elevated CHW) and confirmed in the design criteria schedule. Systems shall be arranged for low return temperatures to protect seasonal coefficient of performance.

GAP: Peak heating/cooling loads, heat-pump duties, CHW/LTHW flow-return temperatures and COP/SCOP targets to be populated from the impact/energy calc via cross-check.

3.3 Air Handling & Ventilation

Primary fresh air shall be provided by air handling units incorporating high-efficiency thermal-wheel or plate heat recovery and, where required, an integral heat pump to temper the supply air. Units shall draw the best-quality external air available, with intakes and discharges positioned and separated to prevent cross-contamination. Ductwork shall be constructed and tested to DW/144 for the relevant pressure class, and specific fan power shall not exceed the Part L / design limit.

GAP: AHU supply volumes, specific fan power, heat-recovery efficiency and fresh-air rates to be populated from the ventilation calc via cross-check.

3.4 On-Floor HVAC Strategy

Occupied floorplates shall be conditioned by a terminal system (e.g. fan coil units) mounted at the soffit at the density recommended by the British Council of Offices, distributing chilled and low temperature hot water from the core risers. The arrangement shall provide independent perimeter and internal-zone control, coordinate with the ceiling and raised-floor service zones, and allow for the on-floor loading flexibility required for future tenant fit-out (Cat A / Cat B demarcation).

GAP: Terminal-unit density, zoning, service-zone depths and on-floor spare capacity to be authored against the space plan and confirmed by calc.

3.5 Ancillary Ventilation

Dedicated supply and extract ventilation shall be provided to ancillary spaces at the air change rates appropriate to each use, ducted to atmosphere clear of intakes, with make-up air provided as necessary. Typical provisions include:

• Toilet and shower areas — mechanical extract to CIBSE / Part F rates with transfer make-up air.
• Comms and plant rooms — cooling and ventilation to maintain equipment ambient limits.
• Refuse / bin stores — dedicated extract to control odour and fire risk, at the rate required by CIBSE / Part F.
• Kitchen / catering areas — extract canopies and interlocked supply where provided.

GAP: Ancillary space schedule and confirmed air change rates to be authored against the room data sheets.

3.6 Smoke Ventilation

Smoke ventilation shall be provided to protected escape routes, and to the car park where applicable, in accordance with the fire engineering strategy, Approved Document B and BS 9999 / BS 7346. Smoke extract and make-up ductwork, dampers and fans shall be rated for the required fire integrity and high-temperature operation, and shall be monitored and controlled via the life-safety controls. The detailed smoke strategy is a Contractor's Designed Portion coordinated with the fire engineer.

GAP: Number and arrangement of smoke zones, extract rates and fan ratings to be confirmed with the fire engineering strategy.

4.1 Scope of Works

The Contractor is to design (CDP), supply, install, test and commission complete electrical services comprising the incoming intake and distribution, LV switchgear and distribution boards, small power, containment, earthing and bonding, lightning protection and the fire detection and alarm system, all in accordance with BS 7671 (18th Edition) and the Materials & Workmanship specification.

Materials & Workmanship Specification (Electrical)

4.2 HV Distribution

Where an HV supply is adopted, HV switchgear and packaged transformer substations shall be provided to the DNO's and the design brief's resilience requirements, with HV cabling installed on dedicated diverse routes. HV works shall be undertaken by approved authorised persons and commissioned in accordance with the relevant Energy Networks Association engineering recommendations.

GAP: HV supply arrangement, transformer ratings and redundancy (e.g. N+1) to be confirmed and cross-checked against the electrical load calc.

4.3 LV Distribution

The main LV switchboard shall be the source of primary distribution, manufactured and tested to BS EN 61439-1, with the form of separation, ingress protection and fault rating required by the design. It shall incorporate surge protection and, where required, a generator connection facility. Outgoing ways shall be provided with digital multi-function metering connected to the BMS/EMS. Life-safety distribution boards and cabling shall be segregated in dedicated fire-rated enclosures on diverse routes. Distribution boards shall be sized with adequate spare capacity for future load growth as agreed with the design team.

GAP: Main switchboard rating, form/IP, fault level and target spare capacity to be confirmed and cross-checked against the electrical load calc.

4.4 Small Power Installations

Small power shall be provided to landlord and tenant areas via distribution boards, final circuits and accessories to the density and layout appropriate to each space. Accessories operable by occupants shall be mounted at accessible heights and provided with colour contrast to meet Approved Document Part M. Dedicated and cleaned supplies shall be provided to IT and mechanical plant as required.

GAP: Small-power densities, dedicated supplies and tenant demarcation to be authored against the space plan.

4.5 Electric Vehicle Charging

Electric vehicle charging provision shall be made in accordance with the Building Regulations (Approved Document S) and the planning approval, including active charge points and cable-route provision for future expansion, with load management to coordinate with the available supply capacity.

GAP: Number of active EV charge points, ratings and passive provision to be confirmed with the planning condition and load strategy.

4.6 Cable Management & Containment

Cable containment (tray, ladder, trunking, basket and conduit) shall be provided on coordinated primary and secondary routes with adequate spare capacity, segregation between services categories, and fire-stopping at all compartment penetrations. Life-safety and normal services shall be segregated onto independent, diversely-routed containment.

4.7 Earthing, Bonding & Lightning Protection

A complete earthing and bonding installation shall be provided in accordance with BS 7671, including main and supplementary bonding and, where required, clean earths for sensitive electronic equipment. A lightning protection and surge protection system shall be provided where indicated by a risk assessment to BS EN 62305, bonded to the building earthing system.

GAP: Lightning-protection risk assessment (BS EN 62305) outcome and earthing arrangement to be confirmed.

4.8 Fire Detection & Alarm

An analogue addressable fire detection and alarm system shall be provided throughout the building in accordance with BS 5839-1 and the fire strategy, with the system category, detection coverage, manual call point spacing and cause-and-effect confirmed with the fire engineer. Interfaces shall be provided to the smoke ventilation, life-safety power, lifts, door holders and access control. Aspirating detection shall be provided where standard detection is impractical.

GAP: Fire alarm category (e.g. L2), zoning and cause-and-effect matrix to be confirmed with the fire strategy.

5.1 General Lighting

General lighting shall be high-efficiency LED throughout, designed to the maintained illuminance, uniformity, glare (UGR) and colour-rendering criteria of BS EN 12464-1 and the SLL Code for Lighting for each space, whilst meeting the Part L lighting-efficacy (luminaire lm/W) and installed power-density targets. Luminaires shall be selected for the ceiling type, maintenance access and the targeted circadian / wellbeing criteria where applicable.

GAP: Maintained lux, UGR and installed power density per space to be authored from the lighting design and confirmed by calc.

5.2 Lighting Controls

An addressable lighting control system shall provide automatic presence/absence detection and daylight-linked dimming to meet Part L control requirements and the BREEAM Ene credits, with local manual override, scene control to relevant spaces, and monitoring/scheduling via the BMS/EMS. Controls shall be zoned to suit the space plan and future tenant subdivision.

5.3 External Lighting

External and amenity lighting shall be provided to the approaches, car park and landscaped areas to BS 5489-1 and BS EN 12464-2, controlled by photocell and time schedule, and designed to minimise obtrusive light and comply with the planning lighting conditions and any ecological (dark-corridor) requirements.

GAP: External lighting levels, luminaire schedule and planning/ecology constraints to be confirmed.

5.4 Emergency Lighting

A self-testing addressable emergency lighting installation shall be provided to BS 5266-1 and BS EN 1838, providing not less than 1 lux on the centre-line of escape routes and illumination of escape signage, fire-fighting equipment and call points, with a minimum three-hour duration. Illuminated and non-illuminated exit signage shall comply with the fire strategy and the Health and Safety (Safety Signs and Signals) Regulations.

6.1 Scope of Works

The Contractor is to design (CDP), supply, install, test and commission complete public health services comprising domestic cold and hot water, above-ground foul and waste drainage, rainwater drainage and, where required, fire-suppression water storage and distribution, in accordance with BS 8558, BS EN 12056, the Water Fittings Regulations and the Materials & Workmanship specification.

Materials & Workmanship Specification (Public Health)

6.2 Cold Water Services

Domestic cold water shall be distributed from the incoming main, with break tank and packaged variable-speed booster set where the mains pressure/flow is insufficient, sized on the diversified demand with appropriate storage. The installation shall comply with BS 8558 and the Water Fittings Regulations, incorporate verifiable backflow prevention to each fluid category, and on completion be flushed and disinfected to BS 8558 / BS EN 806-4 with sampling for legionella to the water safety plan.

GAP: Cold-water demand, storage volume and booster duty to be populated from the public-health demand calc via cross-check.

6.3 Hot Water Services

Domestic hot water shall be generated by low-carbon plant (e.g. high-temperature water/air source heat pumps with storage calorifiers) sized on the diversified demand, distributed with a secondary return and thermostatic balancing to maintain temperature and minimise dead-legs. The installation shall meet the legionella-control temperature regime of HSE L8 / HSG274, with thermostatic mixing valves serving outlets where scald risk requires.

GAP: Hot-water demand, generation plant duty, storage and distribution temperatures to be populated from the public-health calc via cross-check.

6.4 Above-Ground Foul & Waste Drainage

Soil, waste and ventilating pipework shall be designed to BS EN 12056-2, arranged for access to the internal bore for clearing obstructions above the flood level of the highest appliance served, with ventilating stacks discharging to atmosphere clear of ventilation intakes and openable windows. Large-radius bends shall be used at the base of stacks. The installation shall be tested for air-tightness on completion in accordance with BS EN 12056-2.

6.5 Rainwater Drainage

Roof and paved-area rainwater shall be drained by a system designed to BS EN 12056-3 / BS 8490 for the relevant rainfall intensity and roof configuration (gravity or syphonic as appropriate), coordinated with the below-ground drainage and any attenuation / SuDS strategy, with overflow provision to protect the building fabric.

GAP: Design rainfall intensity, roof areas and attenuation strategy to be confirmed with the civil/drainage design.

6.6 Sprinklers & Fire Suppression

Where required by the fire strategy or insurer, an automatic sprinkler / fire-suppression installation shall be provided to BS EN 12845 / LPC Rules, with dedicated water storage and pump set (electric and/or diesel) housed in a ventilated pump room. The system extent, hazard classification and water supply arrangement are a Contractor's Designed Portion coordinated with the fire engineer and insurer.

GAP: Confirm whether suppression is required; hazard class, storage volume and pump duty to be confirmed with the fire strategy / insurer.

7.1 Building Management System

An open-protocol (BACnet) Building Management System shall be provided to monitor and control the building services, arranged in accordance with the recommendations of CIBSE Guide H and the design brief. A head-end/supervisor with remote secure web access shall be provided, together with field controllers, sensors and actuators, and interfaces to packaged plant, the electrical metering and the life-safety systems.

7.1.1 Performance Objectives

• Maintain the specified internal environmental conditions efficiently across all operating modes.
• Start, stop and sequence plant to minimise energy use (optimum start/stop, setback, free cooling).
• Monitor plant status and raise prioritised alarms; log trends for performance verification.
• Take defined corrective action on fire, fault or power-loss in coordination with the life-safety systems.

7.2 Controls Strategy

Detailed control strategies (points schedules, sequences of operation and cause-and-effect) shall be developed for each system by the Contractor and submitted for review. Strategies shall include time scheduling, space-temperature and CO₂/air-quality control, heat-pump and AHU sequencing, and fire/smoke damper monitoring, with all set-points adjustable and secured against unauthorised change.

GAP: System-specific points schedules and sequences of operation to be authored as the design develops.

7.3 Energy Metering

Sub-metering of electrical, thermal and water consumption shall be provided to comply with Part L and CIBSE TM39, connected to the BMS/EMS for automatic monitoring, logging and reporting. Meters shall be MID-compliant where used for billing, and metering shall be structured to allow landlord/tenant apportionment and end-use disaggregation.

8.1 General

Passenger, goods and firefighting/evacuation lifts shall be provided as required by the building form and the fire strategy, designed and installed to the Lifts Regulations, BS EN 81-20/-50 and, for accessibility, BS EN 81-70. Firefighting and evacuation lifts shall additionally comply with BS EN 81-72/-76 and BS 9999. Machine-room-less (MRL) gearless drives with variable-voltage variable-frequency control and regenerative drives shall be provided for efficiency.

8.2 Traffic & Performance Criteria

Lift provision shall be verified by a traffic analysis to the applicable BCO guide for the design population, achieving the target up-peak handling capacity and waiting/destination times, with the quality-of-service criteria (levelling accuracy, ride quality and door timing) specified. Shaft ventilation shall be provided to the required proportion of the shaft cross-sectional area.

GAP: Design population, traffic-analysis targets (handling capacity %, waiting/destination times) and speeds to be confirmed against the BCO guide and space plan.

8.3 Lift Schedule

GAP: Project lift schedule (number, type, rated load, speed, travel, entrances and drive) to be authored per project — not shipped as a default (project-specific selection).

9.1 Document Register

A register of the documents forming and referenced by this specification (design reports, drawings, schedules and third-party consultant documents) shall be maintained and issued under document control.

GAP: Project document register to be populated per project under the ISO 19650 information-management process.

9.2 Design Drawings

The design intent drawings, schematics and single-line diagrams referenced throughout this specification are listed here for information; the drawing register defines the current issued status.

GAP: Project drawing register to be populated per project.

9.3 Equipment Schedules

Equipment and system schedules are maintained in the project schedule library and are cross-checked against this specification; scheduled duties populate the equipment call-outs in the clauses above.

Project Schedule Library

9.4 Materials & Workmanship Specifications

The materials and workmanship (M&W) specifications define the products and installation standards for each system and are read together with the descriptive clauses above; where a descriptive clause states a performance requirement, the corresponding M&W clause governs the materials and workmanship.

Materials & Workmanship Specification