Executive Summary
Survey conducted at the Northgate Distribution Centre canteen on 30 April 2026 to assess existing ventilation provision, inspect smoke dampers, and inform a fresh air design proposal.
Critical Fresh Air Shortfall
The canteen ventilation system is delivering only 0.248 m³/s of the 0.9 m³/s required for 75-person peak occupancy per BS EN 16798-1 Category II.
This equates to 3.3 L/s per person against a target of approximately 12 L/s per person — a substantial shortfall requiring system upgrade or replacement.
Project Background
Context for the instruction, scope of works, and reference documentation.
Following instruction from Apex Project Consultants (on behalf of Harland Property Management and Northgate Logistics Group) to design sufficient fresh air into the canteen space and assess non-operating smoke dampers, Built AI attended site on 30 April 2026.
Scope of Works
Item 1 — Measured Survey
Measured survey of canteen (Room 1R), visual inspection and photographic record, in-situ air volume measurement at each supply diffuser using calibrated balometer hood.
Item 2 — Smoke Damper Survey
Visual inspection, accessibility check, condition assessment, and operational test of fire/smoke dampers on canteen-connected ventilation routes.
Item 3 — Fresh Air Design
Desktop design producing a single buildable option to deliver approximately 0.9 m³/s fresh air per BS EN 16798-1 Category II for 75-person peak occupancy.
Item 4 — Damper Remediation
Schedule of surveyed dampers with classification, indicative repair/replacement cost, and recommended action per damper.
Reference Documentation
Original Original contractor drawing 95-6816-M13 Rev C (1995, "For Construction" — original fit-out contractor). Note: duct layout no longer matches 1995 drawing — sections removed or modified during subsequent refurbishments.
Site Information
Key property and stakeholder details.
Airflow Measurement Results
In-situ air volume measurements taken at each of the six canteen supply diffusers using a calibrated balometer hood.
| Supply Grill | Velocity (m/s) | Flow (L/s) | Flow (m³/s) | VCD Status |
|---|---|---|---|---|
| #1 | 3.50 | 22.9 | 0.0229 | Circular VCD |
| #2 | 8.49 | 56.1 | 0.0561 | No VCD |
| #3 | 6.63 | 43.8 | 0.0438 | Rect VCD — OK |
| #4 | 4.86 | 31.9 | 0.0319 | Circular VCD — OK |
| #5 | 8.01 | 52.9 | 0.0529 | Rect VCD — OK |
| #6 | 6.08 | 40.0 | 0.0400 | Rect VCD — OK |
| Total Measured | — | 247.6 | 0.2476 | 27% of 0.9 m³/s target |
Airflow per Supply Grill (L/s)
Measured vs Required (m³/s)
Occupancy Analysis
Performance at varying occupancy levels. During the survey ~30+ people were observed at peak — staff confirmed this was considered "busy". Employees had opened windows to cool the space.
| Occupancy | L/s per Person | % of Target | Status | Assessment |
|---|---|---|---|---|
| 75 (design) | 3.3 | 27% | Fail | Grossly insufficient |
| 40 (busy) | 6.2 | 52% | Poor | Below minimum acceptable |
| 30 (observed) | 8.3 | 69% | Marginal | Below recommended — comfort issues |
| ~20 | 12.4 | 103% | OK | Meets guidance at reduced occupancy only |
Fresh Air per Person at Varying Occupancy
Conclusion: The system can only support adequate ventilation for approximately 20 persons. At typical occupancy (~30), the canteen is stuffy and hot. The system requires upgrade or replacement to meet current standards.
Damper Assessment
Assessment of smoke dampers and manual volume control dampers on the canteen ventilation system.
Annotated Duct Layout — As Surveyed
Thick red line = Smoke Damper | Thin red line = Rectangular VCD | Red dot = Circular VCD | Blue = Active ductwork
Smoke Dampers
Magnet confirmed in working order. No remediation required.
Stuck in closed position, not re-magnetising. Was restricting airflow. Manually opened for survey measurements, returned to original condition. Replacement required.
Volume Control Dampers
All other dampers are manual VCDs for airflow balancing. No additional fire/smoke dampers identified on accessible sections.
| Location | Type | Size | Status |
|---|---|---|---|
| Grill #1 | Circular VCD | ø200 | Operational |
| Grill #2 | — | — | No VCD Fitted |
| Grill #3 | Rectangular VCD | 400×300 | Operational |
| Grill #4 | Circular VCD | ø200 | Operational |
| Grill #5 | Rectangular VCD | 450×200 | Operational |
| Grill #6 | Rectangular VCD | — | Operational |
Key Observations
Additional findings recorded during the survey relevant to the design proposal.
No Canteen Extract Ventilation
No dedicated extract serving the canteen or kitchen area. Kitchen contains light-duty appliances only (microwaves, oven, no hob), but general extract would typically be expected.
No Male WC/Shower Supply
No supply ventilation to Male WC or Male shower areas following refurbishment. Should be addressed as part of any upgrade.
Decommissioned Kitchen Ventilation
Both kitchen supply and extract ductwork decommissioned. Connections remain visible but inactive.
Duct Layout Differs from 1995 Drawing
Current layout does not match original 1995 drawing. Sections removed/modified during previous refurbishments.
Missing Ductwork Insulation
Ductwork generally in good condition but missing insulation in some sections.
Dripping Overflow — Roof
Dripping overflow observed at roof level. Higher access not available. Investigate separately.
Shared AHU Control
Kitchen AHU panel isolated. All canteen ventilation runs from Office AHU panel. Access via locked ladder in service corridor.
480mm Ceiling Void
Limited above-ceiling space constrains ductwork routing for any new supply/extract system.
No Access Panels Near VCDs
No access panels near manual VCDs. Provision should be included in remedial scope.
Design Intent & Recommendations
Proposed strategy to deliver compliant fresh air provision, addressing the shortfall and defects identified.
Fresh Air Supply Upgrade
Replace or supplement existing supply to achieve 0.9 m³/s. Likely AHU replacement, retaining existing ductwork where condition permits.
Canteen Extract Provision
Introduce general extract ventilation to manage heat, odours, and ensure balanced air movement.
Hallway Smoke Damper
Replace faulty hallway smoke damper (stuck closed, not re-magnetising). Fire safety compliance item — prompt attention.
Ductwork & Access
Make good missing insulation. Install access panels near VCDs. Fit VCD to Grill #2 branch.
Male WC/Shower Ventilation
Include supply ventilation to Male WC and shower as part of upgrade scope.
Next Steps
Commission R&D asbestos survey before intrusive works. Proceed to detailed design and tender within 60 days.
Constraints & Risks
Known constraints for the design and installation phases.
| Item | Detail | Impact |
|---|---|---|
| Ceiling void | 480mm — constrains ductwork routing | Design constraint |
| Asbestos | No R&D survey — recommended before intrusive works | Must resolve |
| Legacy system | 1995 drawing does not reflect current layout | Programme risk |
| Power | Available for new AHU | Confirmed OK |
| Roof/plant space | Space available for replacement AHU | Feasible |
| Access | Locked ladder; limited void access near VCDs | Logistics |
Explicit Exclusions
Not included: asbestos survey; roof structural appraisal; BMS interrogation; kitchen canopy/DW-172 assessment; acoustic assessment; Smoking Room 9R works; transfer grilles outside canteen; TR/19 cleaning; installation, materials, or commissioning.
Photo Gallery
Survey photographs recorded on 30 April 2026 by M. Taylor, Built AI. Click any photograph to view full screen.
Document Control
Revision history, approvals, and distribution.
Revision History
| Rev | Date | Description | Author | Reviewed | Status |
|---|---|---|---|---|---|
| 0 | 01 May 2026 | Draft for client review | M. Taylor | Built AI Operations | Draft |
| 1 | — | Issued for approval | — | — | Pending |
Distribution
| Name | Organisation | Role | Copy |
|---|---|---|---|
| R. Thompson | Apex Project Consultants / Harland PM | Project Manager | Digital |
| S. Mitchell | Apex Project Consultants / Harland PM | Senior Project Manager | Digital |
| J. Wheeler | Harland PM | Site Contract Manager | Digital |
| Built AI Operations | BuiltAI Intelligence Ltd | Group COO | Digital |
| M. Taylor | Built AI | Project Manager | Digital |
| Built AI Technical | Built AI | cc | Digital |