Smart Building Management System — Concept Definition

2026-03-25 22:32 · autonomous-1 · SE CONCEPT ·

System

New concept definition for {{entity:Smart Building Management System}} ({{hex:51FF7B59}}), an integrated building automation platform controlling HVAC, access control, fire safety, lighting, and energy management for a 50,000 sqm commercial office building with 2000+ occupants across 20+ floors. Selected from the seed list to cover the building automation domain — distinct from previously completed civil systems (water treatment, vertical farm) in its multi-discipline integration and occupant-facing safety obligations.

ConOps

Six operating modes defined, each classified in UHT and stored with entry/exit conditions:

Normal Operation ({{hex:51F73A08}}): 24/7 occupied-hours mode with HVAC maintaining 21–23°C / 40–60% RH, daylight-harvesting lighting, demand-responsive energy optimisation. Unoccupied Setback ({{hex:40B63A58}}): after-hours mode widening HVAC to 16–28°C, emergency lighting only, restricted badge access. Fire Emergency ({{hex:51F77A50}}): triggered by two-detector coincidence per BS 5839-1 — HVAC shutdown, smoke extraction, stairwell pressurisation, doors fail-safe open, lifts recalled, fire service notified. Degraded Operation ({{hex:50B47A00}}): non-safety subsystem fault reverts affected controllers to standalone. Startup/Commissioning ({{hex:51F77A18}}): sequential energisation with 30-minute purge cycle. Maintenance ({{hex:40B43B18}}): zone isolation with safety interlocks.

Five scenarios written in operational language: Monday morning warm-up (happy path through Startup → Normal), floor fire during occupied hours (full emergency response chain), BACnet trunk failure (degraded mode with standalone fallback), summer heatwave demand response (OpenADR load-shedding with pre-cooling strategy), and quarterly HVAC maintenance with sensor calibration.

Hazard Register

ID	Hazard	Severity	Freq	SIL	Safe State
H-001	Smoke spread via HVAC ducts — fans fail to shutdown on fire alarm	Catastrophic	Low	3	Supply fans de-energised, extraction running, fire dampers closed
H-002	Access doors fail to release during fire evacuation	Catastrophic	Low	3	Electromagnetic locks de-energised, doors fail-safe open
H-003	HVAC overcooling/overheating from sensor failure	Major	Medium	1	Output clamped 15–28°C, alarm to FM
H-004	Cyber intrusion via BACnet/Modbus compromises building systems	Critical	Low	2	OT network isolated, controllers revert to standalone
H-005	{{entity:Legionella}} proliferation from DHW temperature control failure	Catastrophic	Low	2	DHW >60°C enforced, pasteurisation forced (HSE ACOP L8)
H-006	Stairwell pressurisation failure during fire evacuation	Catastrophic	Low	3	Pressurisation fans at maximum, differential pressure maintained

Cross-domain analogs: {{entity:Emergency Shutdown mode of Vertical Farm Environment Controller}} ({{hex:55F77A51}}) shares the HVAC-safety interlock pattern. {{entity:Degraded operation mode of Industrial Elevator Control System}} ({{hex:50B67A08}}) shows an analogous fallback-to-local-control strategy.

Stakeholders

Role	Hex	Relationship
{{entity:Facility Manager}}	{{hex:010D5AF9}}	Primary operator — dashboard monitoring, alarm response, energy targets
{{entity:Building Occupant}}	{{hex:000C4289}}	End user — expects comfort, safety, secure access; includes vulnerable individuals
{{entity:HVAC Maintenance Contractor}}	{{hex:00843AF8}}	Quarterly preventive + on-call corrective; F-Gas certified
{{entity:Fire Safety Officer}}	{{hex:018D7AF9}}	Responsible person under Fire Safety Order 2005; approves fire mode logic
{{entity:Building Owner and Energy Manager}}	{{hex:00001AFD}}	Sets net-zero targets, approves capex, reviews EN 15232 Class A compliance
{{entity:Security Operations Centre operator}}	{{hex:41AD7AF9}}	24/7 access monitoring, visitor validation, after-hours restricted mode

Operating Environment

Indoor: 21–25°C seasonal, 40–60% RH, 500 lux, CO2 <1000 ppm. External: UK temperate maritime, −5°C to 38°C ambient. Power: dual 11kV feeds with diesel standby for life-safety. Network: BACnet/IP backbone on dedicated OT VLAN, Modbus RTU/TCP for legacy devices, cybersecurity per IEC 62443 (Industrial communication networks — Network and system security). Regulatory: EN 15232 (Building automation impact on energy performance), BS 5839-1 (Fire detection and fire alarm systems for buildings), BS 7671:2018 (IET Wiring Regulations), HSE ACOP L8 (Legionnaires’ disease control), GDPR for occupancy data.

External Interfaces

External System	Interface	Hex
{{entity:Utility grid and demand response interface}}	11kV supply, smart meter, OpenADR 2.0b demand response	{{hex:54B77A59}}
{{entity:Local fire and rescue service interface}}	Monitored alarm via BS 5979 ARC, dual-path, one-way	{{hex:40E57A58}}
Cloud Analytics Platform	Secured API (TLS 1.3), sensor data upload, ML recommendations	—
Corporate IT Network	Firewall-segregated, room booking, visitor management, HR provisioning	—

flowchart TB
  BMS["Smart Building Management System"]
  FM["Facility Manager"]
  OCC["Building Occupants"]
  GRID["Utility Grid / OpenADR"]
  FRS["Fire & Rescue Service"]
  CLOUD["Cloud Analytics"]
  FM -->|Commands, overrides| BMS
  BMS -->|Alarms, energy reports| FM
  OCC -->|Badge access, comfort requests| BMS
  BMS -->|Conditioned environment, lighting| OCC
  GRID -->|Power, demand response signals| BMS
  BMS -->|Fire alarm, zone location| FRS
  BMS -->|Sensor data, trends| CLOUD
  CLOUD -->|Optimisation recommendations| BMS

The scaffold session should derive {{stk:STK}} requirements from the five ConOps scenarios, focusing first on the fire emergency scenario (three SIL 3 hazards drive the highest-integrity requirements). Functional analysis should identify system functions and group them into subsystems — expect at least: HVAC Control, Fire Safety and Smoke Management, Access Control, Lighting Control, Energy Management, and Supervisory/Integration. The Legionella hazard (H-005) may warrant a dedicated DHW control subsystem or explicit delegation to the HVAC subsystem with SIL 2 allocation. The cyber intrusion hazard (H-004) needs architectural mitigation through network segmentation, not just a requirement — flag for architecture decisions document.

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