Chapter 7
Mechanical Ventilation & Smoke Control Systems
Chapter 7 governs the design, installation and maintenance of air-conditioning, mechanical ventilation, pressurisation and smoke control systems in buildings to limit fire and smoke spread and to maintain tenable conditions for evacuation and firefighting. It sets out ductwork construction rules, fire damper requirements, special ventilation requirements for exits and protected spaces, pressurisation performance criteria, smoke extraction and purging system designs, and mandatory redundancy provisions for all critical life-safety ventilation systems.
Scope: All buildings (except PG I where explicitly exempted) that incorporate air-conditioning or mechanical ventilation systems, pressurised exit staircases or corridors, or engineered smoke control systems. Specific clauses apply to hotels, car parks, kitchens, battery rooms, and buildings with large or basement compartments.
Source: SCDF Code of Practice for Fire Precautions in Buildings 2023. This is a guidance summary — always verify against the full Fire Code clause text.
Critical points
An N+1 standby fan must be provided for MV systems serving smoke-free/fire lift lobbies, exit staircases, and essential rooms (sprinkler/wet riser/hose reel pump rooms, generator room, FCC). The standby fan must activate automatically on duty fan failure.
CriticalClause 7.5.1a(1)N+1 redundancy is required for engineered smoke control systems and car park smoke purging systems (for ductless systems, redundancy is achieved by operating ≥2 zones).
CriticalClause 7.5.1a(2)–(3)N+1 redundancy is required for pressurisation systems for smoke-free/fire lift lobbies, exit staircases and hotel internal guestroom corridors.
CriticalClause 7.5.1a(4)Where automatic smoke ventilators (non-powered) are used as part of smoke control, at least 10% redundancy in quantity is required, rounded up to whole numbers based on the largest ventilator size used.
ImportantClause 7.5.1b
Compliance thresholds
| Parameter | Value | Condition | Clause |
|---|---|---|---|
| Standby fan redundancy — powered systems | N+1 (one standby fan per system) | MV for lobbies/staircases/essential rooms, smoke control, pressurisation systems | Clause 7.5.1a |
| Redundancy for ductless jet fan system | At least 2 zones in operation (N+1 per zone not required) | Ductless car park jet fan smoke purging system | Clause 7.5.1a — Note |
| Natural ventilator quantity redundancy | At least 10% (rounded up, based on largest size) | Automatic smoke ventilators in smoke control system | Clause 7.5.1b |
Interactive decision tree
Identify which fire safety ventilation systems are installed in the building.