a.    Powered system

A standby fan (N+1) shall be provided for each of the following systems, such that in the event one of the duty fans fails or taken out of service, the standby fan shall be automatically activated to meet the required ventilation rate. 

(1)    mechanical ventilation systems for: 

(a)   smoke-free/ fire lift lobbies;

(b)   exit staircases; and

(c)   essential rooms (e.g., sprinkler/ wet riser/ hydrant/ hose  reel pump room, standby generator room, FCC, etc.).

(2)    engineered smoke control systems; 

(3)     car park smoke purging systems*; and 

(4)     pressurisation systems for smoke-free/ fire lift lobbies, exit staircase and hotel internal guestroom corridor.

Note * redundancy (N+1) achieved by having at least 2 zones for ductless system in operation, in which N+1 fans for each zone is not required. 

b.      Non-powered system

Where automatic smoke ventilators are used as part of the smoke control system, there shall be at least 10% redundancy on the quantities of ventilators and shall be located such that they are not affected by the wind. The quantity of the redundant ventilators shall be round up to whole numbers, based on the largest size of the ventilators used.