Fire Code

Where an air-conditioning system is provided in lieu of a mechanical ventilation system for emergencies, all the requirements specified in this Code for mechanical ventilation systems shall apply to the air-conditioning system.

Ducts for air-conditioning and mechanical ventilation systems shall be constructed in compliance with all of the following requirements:

1. Materials

   Air-conditioning or other ventilation ducts, including framing thereof, shall be constructed of steel, aluminium, glass fibre batt or mineral wool batt or other approved materials. 

2. Support 

   Air-conditioning or other ventilation ducts shall be adequately supported. 

3. Duct linings & coverings

   Duct covering and lining shall be non-combustible. However, if it is necessary to use combustible material, it shall:

   1. when tested in accordance with methods specified in this Code, have a surface flame spread rating of not lower than Class 1, except in areas of a building where Class 0 flame spreading rating is required for the ceiling construction under this Code, a Class 0 rating for the covering and lining materials shall instead be required;

   2. when involved in fire, generate a minimum amount of smoke and toxic gases; and

   3. be at least 1m away from a fire damper.

4. Flexible joints and connections

   1. Flexible connections at the ends of ventilation ductwork connecting terminal units, extract units and ventilation grilles shall not exceed 4m.

   2. Flexible joints, which are normally provided to prevent and/or allow for thermal movements in the duct system, shall not exceed 250mm in length.

   3. Flexible joints shall be made of material classified as ‘not easily ignitable’ when tested under BS 476: Part 5.

5. Duct enclosure

   Enclosure of ducts shall comply with the requirements in Cl.3.8.9a..

6. Ductwork through smoke-free or fire lift lobbies

   Ventilation ducts should not pass through smoke-free or fire lift lobbies. Where unavoidable, the part of the ventilation duct within the lobby shall be enclosed in masonry construction with fire resistance rating at least equal to that of the elements of structure. If other forms of fire resisting construction are used, a fire damper shall be fitted where the duct penetrates the lobby enclosure.

7. Ductwork through separating walls

   No air-conditioning or ventilation duct shall penetrate separating walls.

8. Fire-rated duct

   1. Where proprietary fire-rated materials are used to construct the fire-rated duct, the fire rating of the fire-rated duct shall have the same period of fire resistance as the wall or floor it penetrates.

   2. Proprietary fire-rated duct shall be tested to BS 476 Part 24 or equivalent and its usage be approved by the SCDF.

   3. Running of non-fire-rated duct and/ or other building services above the proprietary fire-rated duct should be avoided. When unavoidable due to physical constraints, the supports to such non-fire-rated duct and/ or other building services running above the proprietary fire-rated duct shall be strengthened, such that the tensile stress generated on the supports shall not exceed 10N/mm². The non-fire-rated duct and/ or building services shall also be adequately protected to prevent collapse in a fire which will otherwise affect the stability of the proprietary fire-rated duct below.

   4. Fans forming part of a fire-rated duct shall also be enclosed in the same fire-rated enclosure.

9. Control panel

   1. The location and placement of control panels serving engineered smoke control and smoke purging systems shall be located within a common space such that the panels are clearly visible and readily accessible for operation and maintenance. Control panel shall be mounted at a height not less than 1.5m or not more than 1.8m from the finished floor level.

   2. For control panels serving smoke purging systems, it shall be located at least 1.5m away from fire hazards e.g. control panels for smoke purging system in carparks sited away from vehicle parking lots. Alternatively, the control panel shall be protected with at least 1-hr fire resisting rating enclosure.

Insulation for pipework associated with the air-conditioning and mechanical ventilation systems shall comply with the following requirements:

1. Flame spread rating

   Insulation material for pipework, together with vapour barrier lining and adhesives shall, when tested in accordance with the methods specified in this Code, have a surface flame spread of not lower than Class 1. However, in areas of buildings where Class 0 flame spread is required for the ceiling construction under this Code, a Class 0 rating for the insulation material shall be required.

2. Plastic and foam rubber insulation

   Notwithstanding the requirements of Cl.7.1.3a., the use of plastic and foam rubber insulation materials of a lower classification is permitted if:

   1. it is of the self-extinguishing type; and

   2. the insulation is covered by or encased in a metal sheath or hybrid plaster or other non-combustible cladding material,

   provided that any opening in the element of structure or other part of a building penetrated by the pipework shall be effectively fire-stopped by replacement of the insulation material at the junction of penetration with fire resistant material having equal fire resistance rating. A fire-rated proprietary pipework system can be used if it is tested in the manner acceptable to the SCDF.

A concealed space between the ceiling and floor above it, ceiling and roof, or raised floor and structural floor of a building can be used as a plenum provided:

1. The concealed space contains only:

   1. mineral insulated metal sheathed cable, aluminium sheathed cable, copper sheathed cable, rigid metal conduit, enclosed metal trunking, flexible metal conduit, liquid tight flexible metal conduit in lengths not more than 2m, or metal-cladded cables;

   2. electric equipment that is permitted within the concealed spaces of such structures, if the wiring materials, including fixtures, are suitable for the expected ambient temperature to which they will be subjected;

   3. other ventilation ducts complying with Cl.7.1.2a. to d.;

   4. communication cables for computers, television, telephone and inter-communication systems;

   5. fire protection installations; and

   6. pipes of non-combustible material conveying non-flammable liquids.

2. The supports for the ceiling membrane are of non-combustible material.

3. Exception

   Low-smoke and low-flame plenum rated PVC cables conforming to NFPA 262 can be run exposed in plenum, provided that:

   1. the plenum space is protected by a sprinkler system or gaseous total flooding system; and

   2. a FCU or AHU using a plenum for air return and serving more than one room, is installed with smoke detector(s) at the return air plenum space to shut down the FCU/ AHU upon detection of smoke.

Any fire damper shall have a fire resisting rating of not less than that required for the compartment wall or compartment floor through which the relevant section of the ventilation duct passes. Fire dampers shall be of the type approved by the SCDF and constructed in accordance with the requirements in SS 333.

1. Provision of fire dampers

   Ventilation ducts which pass directly through a compartment wall or compartment floor shall comply with the following:

   1. where the ventilation duct does not form a protected shaft or is not contained within a protecting structure, the duct shall be fitted with a fire damper where it passes through the compartment wall or compartment floor; and

   2. where the ventilation duct forms a protected shaft or is contained within a protecting structure, the duct shall be fitted with fire dampers at the shaft inlets and outlets.

2. Installation of fire dampers

   1. Fire dampers shall be installed so that the casing completely penetrates through the compartment wall or floor, and the casing shall be retained, either:

      1. on both sides by means of flanges in such a manner that it can expand under fire conditions without distorting the blades in the closed position, or

      2. on the accessible side by means of one flange only, which can be fixed to the damper and to the wall through slotted holes to allow for expansion.

   2. Flanges shall be butted against the face of the compartment wall or floor and fixed to the damper casing.

   3. Ductwork connected to the damper shall be attached in such a manner as to ensure that the damper remains securely in position and is fully functional in the event of damage of ductwork.

   4. The clearance between the damper body and the sides of the penetration shall not be less than that of the tested prototype and be not greater than half the width of the angled section of the collar.

   5. The space between the damper body and the opening in the wall or floor shall be fire-stopped.

   6. Vertically positioned fire dampers shall be installed in such a manner that the direction of air flow assists in the closure of the damper.

   7. Connections to fire dampers

      The distance between the plane through a closed fire damper and ducting, flexible connections, duct coverings, internal linings and the like, shall be

      1. not less than 1m when such parts are made of materials with fusing temperatures less than 1000oC;

      2. not less than three times the diagonal or diameter of the damper; and

      3. not less than 2m when such parts are made of materials that are combustible, except for vapour barrier to provide thermal insulation.

   8. Fire damper inspection access doors

      Each fire damper installation shall be provided with an inspection access door in the ventilation duct, either upstream or downstream, as appropriate. The access door dimension shall measure 450mm (length) X 450mm (width); for smaller ducts, the door width dimension can be reduced to the width or depth of the duct. Access doors shall be hinged and fitted with sash locks, and be constructed of minimum 1.25mm suitably braced sheet steel. Openings in ducts shall be stiffened by a sheet steel frame.

3. Prohibition of fire dampers

   Fire dampers shall not be fitted in any of the following locations:

   1. openings in walls of a smoke extract shaft, or a return air shaft which also serves as a smoke extract shaft, or

   2. openings in walls of a protected shaft when the openings have a kitchen exhaust duct passing through it, or

   3. opening in walls of a protected shaft when the openings have a fume hood exhaust duct passing through it, or

   4. anywhere in an air pressurising system, or

   5. in locations explicitly prohibited in this Code.

4. Standards

   Where a fire damper is required by this Code to be installed in an air- conditioning and mechanical ventilation system, its type, details of installation, connection of accessories, inspection door, etc., shall be in accordance with SS 333.

1. The space above a suspended ceiling which forms part of a fire-rated floor ceiling or roof ceiling construction shall not contain ducting, unless said ducting was incorporated in a prototype that qualified for the required fire resistance rating, in which case the ducting shall be identical to that incorporated in the tested prototype.

2. Openings in the ceiling, including openings to enable the ceiling to be used as a plenum, shall be protected by fire dampers identical to those used in the tested prototype. Such openings in the ceiling shall be so arranged that:

   1. no opening is greater in area than that in the corresponding prototype test panel;

   2. the aggregate area of the openings per unit ceiling area does not exceed that of the prototype test panel; and

   3. the proximity of any opening to any structural member is not less than that in the prototype test panel.

1. Openings for the intakes of outdoor air to all air handling systems, mechanical ventilation systems, pressurisation systems of exit staircases and internal corridors, and smoke control systems shall be no less than 5m from any exhaust discharge openings.

2. All return air openings and outdoor air intakes shall be located and arranged such that sources of ignition, such as lighted matches and cigarette butts, which accidentally enter the openings and intakes cannot be deposited onto the filter media.

1. Air plenums

   Air handling systems shall not use protected shafts of exits, smoke-free lobbies, including its concealed space for supply, exhaust or return air plenums.

2. Compartmentation

   1. Where the air handling equipment serves more than one compartment, fire dampers shall be provided in air ducts at penetrations through the compartment walls and floors to comply with the requirements in Cl.7.1.5.

   2. Where AHU rooms are vertically stacked, each AHU room shall be separated by a compartment floor at every level.

3. Smoke detectors

   1. Smoke detectors of approved type shall be incorporated in the return air stream immediately adjacent to:

      1. AHUs serving more than one storey or compartment, or

      2. a single AHU in excess of 15000m³/h.

   2. The function of smoke detectors, where required by this Code, is to initiate action to shut down the AHU automatically when the smoke density in the return air system has become unacceptable for recycling.

4. Stop switch

   Where the AHUs in a building are not centrally controlled, each AHU exceeding 8500m³/h shall be provided with a manual stop switch to facilitate quick shutting down of the fan in the case of fire. For ease of access, this switch shall be located on the wall next to the door opening of the air handling equipment room.

1. Air plenums

   Protected shaft of exits, smoke-free lobbies, including their concealed spaces shall not be used for supply, exhaust or return air plenum of air handling systems.

2. Exit staircase and internal exit passageway

   A mechanical ventilation system for each exit staircase and internal exit passageway, if provided, shall be an independent system of supply mode only exclusive to the particular staircase and internal exit passageway, and it shall comply with all of the following requirements:

   1. Supply air for the system shall be drawn directly from the external space, with intake point not less than 5m from any exhaust discharge openings.

   2. For exit staircase serving more than four storeys, supply air shall be conveyed via a vertical duct extending throughout the staircase height and discharging through outlets distributed at alternate floors.

   3. Where the supply air duct serving the exit staircase has to penetrate the staircase enclosure, the portion of the duct where it traverses outside the staircase shall be enclosed in masonry construction or drywall complying with Cl.3.8.7b. of at least the same fire resistance as the elements of structure, and it shall not be fitted with fire dampers.

   4. The ventilation system shall be of supply mode only, and of not less than 4 air changes per hour.

   5. The mechanical ventilation system shall be automatically activated by the building fire alarm system. In addition, a remote manual start-stop switch shall be made available to firefighters at the FCC, or, where there is no FCC, at the fire alarm panel.

   6. Visual indication of the operational status of the mechanical ventilation system shall be provided.

1. The ventilation system shall be of supply mode only of not less than 10 air changes per hour.

2. Supply air shall be drawn directly from the external space with intake point not less than 5m from any exhaust discharge or openings for natural ventilation.

3. Any part of the supply duct running outside the smoke-free or fire lift lobby which it serves shall either be enclosed or constructed to give a 1-hr fire resistance rating. The SCDF may, at its discretion, require a higher fire resistance rating if the duct passes through an area of high fire risk.

4. The mechanical ventilation system shall be automatically activated by the building fire alarm system. In addition, a remote manual start-stop switch shall be made available to firefighters at the FCC, or, where there is no FCC, at the main fire alarm panel.

5. Visual indication of the operational status of the mechanical ventilation system shall be provided.

6. Where air conditioning is required for daily operations, this can be provided via supply and return air duct from the FCU/ AHU outside of the smoke-free/ fire lift lobby. Fire dampers shall be provided in the supply and return air ducts at penetrations through the compartment walls and/or floors. The ducts shall be fire-rated if it forms part of the other services passing through the smoke-free/ fire lift lobbies and/or the duct insulations are not of non-combustible type.

Where mechanical ventilation is installed to provide a smoke-free environment for the room housing the fire pump or emergency generator, such systems shall be independent of each other and of any other system serving other parts of the building, and shall comply with all of the following requirements:

1. Supply air shall be drawn directly from the external space and its intake point shall not be less than 5m from any exhaust discharge openings. Exhaust discharge shall also be direct to the external space.

2. Where the corresponding ducts run outside the room they shall either be enclosed in a structure or be constructed to give at least the same fire rating as the room which they serve, or that of the room through which they traverse, whichever is higher. The rating shall apply to fire exposure from both interior and exterior of the duct or structure. Where the duct risers are required to be enclosed in a protected shaft constructed of masonry or drywall complying with Cl.3.8.7b., they shall be compartmented from the rest of the shaft space containing other ducts or service installations.

3. No fire damper shall be fitted in either supply or exhaust duct required under this clause.

4. A duct serving areas other than rooms housing equipment stated in this clause shall not pass through such rooms.

The FCC can either be air-conditioned, naturally ventilated or mechanically ventilated. The air-conditioning or mechanical ventilation shall be independent of each other and any other system serving other parts of the building. Where air-conditioning or mechanical ventilation is provided, the fan coil unit or ventilation fan serving the FCC can be located within the FCC and shall also comply with all of the following requirements:

1. Supply air shall be drawn directly from the external space and its intake point shall not be less than 5m from any exhaust discharge openings. Exhaust discharge shall also be direct to the external space.

2. Where the corresponding ducts run outside the FCC, they shall either be enclosed in a structure or be constructed to give at least the same fire rating as the room which they serve or that of the room through which they traverse, whichever is higher. Where the duct risers are required to be enclosed in a protected shaft constructed of masonry or drywall complying with Cl.3.8.7b., they shall be compartmented from the rest of the shaft space containing other ducts or service installations.

3. No fire damper shall be fitted in either supply or exhaust duct required under this Clause.

4. A duct serving areas other than the FCC shall not pass through the room.

1. Provision

   A mechanical exhaust system for the cooking area of a kitchen in a hotel, restaurant, coffee house or the like shall be independent of those serving other parts of the building. It shall also comply with all of the following requirements:

   1. The hood and ducts for the exhaust shall have a clearance of 500mm from unprotected combustible materials.

   2. The exhaust shall discharge directly to the external space and shall not be less than 5m from any air intake openings.

   3. The exhaust duct, where it runs outside the kitchen, shall either be enclosed in a structure or be constructed to give at least the same fire rating as the kitchen or that of the room through which it traverses, whichever is higher. The rating shall apply to fire exposure from both interior and exterior of the duct or structure. Where the duct riser is required to be enclosed in a protected shaft constructed of masonry or drywall complying with Cl.3.8.7b., it shall be compartmented from the rest of the shaft space containing other ducts or services installations.

   4. No fire damper shall be fitted in kitchen exhaust ducts.

2. Sharing of kitchen exhaust system

   Sharing of kitchen exhaust system for food and beverage outlets is allowed, provided all of the following conditions are complied with:

   1. For food courts

      1. The food court shall be under a single ownership/ operator.

      2. All kitchen exhaust ducts running outside the food court shall have 1-hr fire resistance rating, or shall not be less than that for the elements of structure, whichever is higher.

   2. For restaurants/small F&B outlets (e.g. snack bars, food kiosks, etc.)

      1. Restaurants and small F&B outlets that are sharing the same kitchen exhaust system shall be located on the same storey and within the aggregate zone area not exceeding 2000m². The maximum length of the aggregate zone covering from the first to the last restaurant/F&B outlet shall not exceed 50m.

      2. The aggregate floor area of the restaurants and F&B outlets shall not exceed 1000m².

      3. Common ducts shall be provided with a common exhaust fan.

      4. The building shall be protected by an automatic fire sprinkler system.

      5. The exhaust hood shall be fitted with a wet chemical fire extinguishing system.

      6. The fire rating of the common kitchen exhaust duct running outside the restaurants shall have 1-hr fire resistance rating, or shall not be less than that for the elements of structure, whichever is higher.

         (Note: Kitchen exhaust ducts include both horizontal and vertical ducts.)

3. Kitchen exhaust duct (KED)

   1. A KED running outside a building shall not be located within 3m of any unprotected openings. This separation distance can be reduced to 1.5m if the unprotected opening is on the same plane as the duct. (See Diagram 7.1.13c.(1) - 1 and  2)

   2. Where the distances mentioned above cannot be achieved, a fire resistant construction having at least ½-hr fire resistance shall be placed between the duct and the unprotected opening. (See Diagram 7.1.13c.(2))

   3. A non-fire-rated KED shall not be located above an LPG storage cabinet, unless they are separated from LPG cylinders by a minimum of 2-hr fire-rated masonry construction above and beside the cylinders. (See Diagram 7.1.13c.(3))

   4. The KED shall be located at least 3m from any unprotected LPG cylinders. Non-fire-rated KED shall be located at least 600mm from the vapouriser or any liquid-phase LPG pipeline. (See Diagram 7.1.13c.(4))

   5. Access panels for KED

      KED shall be provided with openings via access panels to facilitate inspection and maintenance, which shall comply with the following:

      1. Access panels shall be provided to allow the interior of the duct to be viewed without the assistance of tools, to facilitate thorough cleaning. The access panels shall not be obstructed by suspended ceilings, cable routes, pipes or other installations.

      2. Access panels shall be located at the sides of the duct.

      3. Access panels are not required at the duct entry, duct discharge, or sections of the duct which are fire-rated or protected with fire-rated enclosure. Excluding these exempted areas, access panels shall be provided at the following locations:

         1. at changes of ducting direction;

         2. if fire extinguishing systems are provided, to facilitate installation and servicing of the fire extinguishing systems;

         3. within 900mm of each side of exhaust fan assemblies;

         4. at least 40mm from all outside edges of the duct or welded seams; and

         5. in addition to compliance with subclause (i) to (iv), access panels shall be located at maximum 3m intervals for horizontal ducting, and at the top and bottom of sections of vertical ducting which runs solely at the building exterior.

      4. Access panels shall be conspicuously marked with the following wording: ACCESS PANEL – DO NOT OBSTRUCT. The lettering shall be at least 25mm in height, in a colour contrasting with the background.

4. Maintenance

   All kitchen exhaust systems shall be properly maintained in accordance with the following: 

   1. The entire (interior and exterior) exhaust duct and kitchen hood shall be degreased and cleaned at least once every 12 months.

   2. The work shall be carried out by a specialist and the records of cleaning and degreasing shall be kept by the owner/ operator for verification. This requirement shall be included in the Fire Safety Instruction Manual. 

1. Dedicated system

   Mechanical ventilation systems, where required for rooms which involve the use of flammable and explosive substances, shall be independent from those serving other parts of the building. They shall comply with all of the following requirements:

   1. Ventilation system shall consist of exhaust and supply parts with a rate of 20 air changes per hour or any other rates acceptable to the SCDF. The exhaust shall direct to the external space and shall not be less than 5m from any air intake openings.

   2. Where such ducts run outside the room they shall either be enclosed in a structure or be constructed to give at least the same fire rating as the room which they serve or that of the room through which they traverse, whichever is higher. The rating shall apply to fire exposure from both interior and exterior of the duct or structure. Where the duct risers are required to be enclosed in a protected shaft constructed of masonry or drywall complying with Cl.3.8.7b., they shall be compartmented from the rest of the shaft space containing other ducts or service installations.

   3. No fire damper shall be fitted in either a supply or exhaust duct required under this Clause.

   4. Ducts serving other areas shall not pass through rooms involving use of flammable and explosive substances.

2. Sharing of supply air duct

   A common fire-rated supply air duct can serve various compartments within the same floor level or other floor levels, provided:

   1. the compartments are sprinkler-protected;

   2. the compartments are of the same purpose group;

   3. the duct is fitted with a fire damper where it passes through the wall or floor of each fire compartment; and

   4. a dedicated exhaust duct is provided for individual fire compartments and shall be maintained in operation (with the minimum flow rate) even it is under fire mode situation to prevent smoke entering into other fire compartments.

Rooms housing batteries shall comply with the following requirements:

1. The batteries shall be of either vented or sealed type.

2. The room ventilation system shall be designed to limit the maximum concentration of Hydrogen (H2) gas to 1% of the total volume of the room during the worst case event of simultaneous “boost” charging of the batteries. The inlets and outlets of the ventilation system shall be properly located so that there is no stagnant area in the room.

3. Adequate hydrogen gas detectors shall be provided inside the room to monitor the hydrogen concentration and to activate the fan, if necessary, to ensure that the hydrogen concentration level at any part of the room does not exceed 1% of the total volume of the room. Display panels showing the readings of the detectors shall be located at the entrance to the room. At the same time, an alarm signal shall be sent to a manned station such as security control room, guard house or FCC.

4. The design of the battery room ventilation shall be in accordance with BS EN IEC 62485-2 & BS EN IEC 62485-3.

5. For mechanically ventilated battery rooms, the ventilation requirement shall be based on Cl.7.1.15d., or 6 air changes per hour, whichever is higher.

6. No fire damper shall be provided in the essential ventilation system and ducts passing through other compartments shall have 2-hr fire resistance rating.

7. Essential fans and associated electrical controls shall be backed up with a secondary source of power supply.

1. Internal exit staircase

   In any building of which the habitable height exceeds 24m, any internal exit staircases without adequate provision for natural ventilation shall be pressurised to comply with the requirements in this Code. Where the upper part of the staircase is naturally ventilated, its lower part can be provided with mechanical ventilation or pressurisation, whichever is appropriate, in accordance with Cl.2.3.3d.(9).

2. Basement

   In a building comprising more than four basement storeys, exit staircases connected to a fire lift lobby in basement storeys shall be pressurised to comply with the requirements in this Code.

3. PG II occupancy

   Where PG II building is provided with a mechanical ventilation system or pressurisation system for its staircase storey shelter, an automatic smoke detection system complying with SS 645 shall be installed. The smoke detector shall be located at the entrance of each exit staircase at every storey, including the non-residential floors. Activation of any smoke detector shall initiate the operation of the mechanical ventilation system or pressurisation system.

1. When in operation, the pressurisation system shall maintain a pressure differential of not less than 50 Pa between the pressurised exit staircase and the occupied area when all doors are closed.

2. Where a smoke-free lobby is also pressurised, the pressure at the exit staircase shall always be higher.

3. The force required to open any door against the combined resistance of the pressurising air and the automatic door closing mechanism shall not exceed 110N at the door handle.

1. When in operation, the pressurisation system shall maintain an airflow of sufficient velocity through open doors to prevent smoke from entering into the pressurised area.

2. The flow velocity shall be attained when a combination of two doors from any two successive storeys and the main discharge door are fully open.

3. The velocity averaged over the full area of each door opening shall not be less than 1.0 m/s.

1. The rate of supply of pressurised air to the pressurised areas shall be sufficient to make up for loss through leakages into the unpressurised surroundings.

2. Adequate relief of leaked air out of the occupied area shall be provided to avoid a pressure build-up in this area. The relief can be in the form of perimeter leakages or purpose built extraction systems.

1. The number and distribution of injection points for supply of pressurising air to the exit staircase should ensure an even pressure profile complying with Cl.7.2.2.

2. The arrangement of the injection points and the control of the pressurisation system shall be such that when the opening of doors or other factors cause significant variations in pressure difference, the condition in Cl.7.2.2 shall be restored as soon as practicable.

1. All the equipment and the relevant controls associated with the pressurisation system shall be designed and installed to ensure satisfactory operation in the event of a fire.

2. Supply air for the pressurisation system shall be drawn directly from the external space and its intake shall not be less than 5m from any exhaust discharge openings.

3. The pressurisation system shall be automatically activated by the building fire alarm system. In addition, a remote manual start-stop switch shall be made available to firefighters at the FCC, or at the fire alarm panel where there is no FCC. Visual indication of the operation status of the pressurisation system shall be provided.

1. Where internal corridors in hotels are required to be pressurised in compliance with Cl.9.7.2a.(3), the pressure within such corridors shall be higher than that in the guest rooms by 12.5 Pa. Corridor pressurisation shall be activated for the floor on fire and two floors above.

2. The pressure within the smoke-free lobby/ fire lift lobby serving these internal corridors shall be higher than that of the internal corridors by 12.5 Pa. The pressurisation fans serving the smoke-free lobby/ fire lift lobby shall activate on all floors during a fire.

3. Pressure within the internal exit staircases shall comply with Cl.7.2.2a..

1. An engineered smoke control system as specified in Cl.7.4.5 shall be provided where:

   1. the requirements for compartmentation specified in Cl.3.2.1, Cl.3.2.4a. and Cl.3.2.4b. are relaxed under the conditions in Cl.3.2.6 for Atrium spaces in a building, or

   2. the total floor area of any compartment in a building or part of a building exceeds 5000m², or

1. -

   3. the total aggregate floor area of all basement storeys exceeds 2000m², except in any of the following situations:

      1. Where the basement or a portion of the basement is used as a car park, the car park shall comply with the requirements of smoke purging system in accordance with Cl.7.4.3, provided it is compartmented from the rest of the basement.

      2. Where a plant/ equipment room with floor area not exceeding 250m² is compartmented from rest of the basement, two doors remotely located from each other for better reach in firefighting operations shall be provided. The provision of a single door opening for this room is permitted provided the most remote part of the room is less than 8m from the door, and the equipment found inside this room, does not obstruct the throw of a water jet from a firefighting hose.

      3. Where a plant/ equipment room with floor area not exceeding 2000m², is provided with smoke vent in accordance with Cl.7.4.2 or smoke purging system in accordance with Cl.7.4.3.

      4. Where a compartmented service area comprising storerooms or workshops (restricted to staff only) is provided with smoke vent in accordance with Cl.7.4.2, or smoke purging system in accordance with Cl.7.4.3.

      5. Where the basement of a residential development is used as a car park, one office intended for ancillary use is permitted in the car park. The office shall be provided with smoke purging system in accordance with Cl.7.4.3 and compartmented from the rest of the basement. The office floor area shall not exceed 40m².

2. A smoke vent in accordance with Cl.7.4.2 shall be provided if the total aggregate floor area of all basement storeys does not exceed 2000m², except for PG I buildings . In lieu of smoke vents, a smoke purging system or an engineered smoke control system is permissible for car parks or other occupancies respectively.

Smoke vents shall be adequately distributed along the perimeter of the space served, and its outlets shall be easily accessible during firefighting and rescue operations. Smoke vents shall comply with the following requirements:

1. the number and their sizes shall be such that the aggregate effective vent openings shall not be less than 2.5% of the floor area served;

2. the vent outlets, if covered under normal conditions, shall be openable in case of fire;

3. the position of all vent outlets and the areas they serve shall be suitably indicated adjacent to such outlets;

4. where ducts are required to connect the vent to outlets, the ducts shall either be enclosed in structure or be constructed to give at least 1-hr fire resistance rating; and

5. separate ducts and vent outlets shall be provided for each storey.

Smoke purging system, where permitted under this Code in buildings, shall conform to all of the following requirements:

1. The smoke purging system shall be independent of any other system serving other parts of the building.

2. The purging system’s purge rate shall be at least 9 air changes per hour.

3. The purging system shall be activated automatically by the building fire alarm system. In addition, a remote manual start-stop switch shall be located at the FCC, or at main fire alarm panel on first storey (where there is no FCC in the building). Visual indication of the operation status of the smoke purging system shall also be provided with this remote control.

4. Supply air shall be drawn directly from the external space and its intake shall not be less than 5m from any exhaust discharge openings. Outlets for the supply air shall be adequately distributed over the area served.

5. Where there is natural ventilation for the area served based upon evenly distributed openings equal to not less than 2.5% of the floor area of a given storey, such natural ventilation can be considered a satisfactory substitute for the supply part of the smoke purging system.

6. Replacement air shall be provided and if it is supplied by a separate mechanical system, such a system shall be connected to a secondary power supply.

7. Exhaust ducts shall be fabricated from heavy gauge steel of at least 1.2mm thickness.

8. The exhaust fan shall be capable of operating effectively at 250ºC for 2 hours and be connected to a secondary power supply.

1. General

   This system can be used in lieu of a smoke purging system for conventional car parks where passenger cars/light weight vehicles are parked alongside each other with common driveways. It is not intended for mechanised car park systems or other forms of car parking systems.

2. Provision of sprinkler system

   1. The basement car park shall be sprinkler-protected in accordance with the SS CP 52.

   2. The arrangement of the sprinkler heads and the jet fans shall be such that, upon the operation of the jet fans, the effect on the spray pattern of the sprinklers is minimised.

3. Zoning of car park

   1. All car park spaces shall be divided into smoke control zones with each zone not larger than 2000m² (excluding plant rooms and circulation spaces) for the purpose of smoke containment and quicker location of fire. A commissioning test will be carried out using hot smoke to demonstrate that smoke can be contained within each zone and channelled to the extract fans.

   2. Each smoke control zone shall have its own jet fan system (fresh air fans, exhaust air fans and jet fans) to purge smoke from the affected zone. The ducts shall be fabricated from heavy steel gauge steel of 1.2mm thickness. Alternatively, sharing of the fresh air and exhaust air fans is permitted provided the fans, wiring and control panel are protected with at least 1-hr fire resistance rating. The exhaust fan system shall also be designed to run in at least two parts, such that the total exhaust capacity does not fall below 100% of the required rate of extract for the zones affected in the event of failure of any one part. This requirement is also applicable for mechanised supply fan system, if it is used.

4. Jet fan system

   1. The jet fan system shall be activated by the sprinkler system serving the basement car park level and any other areas located within the same level. The activation of the jet fan system shall be confined to the smoke control zone on fire and all its adjacent zones. A firefighter cut-off and activation (override) switch shall be provided at the FCC. As an alternative form of fan activation, the use of smoke detectors to activate the jet fan system is allowed, provided:

      1. the detectors are positioned at the effective mid-range of the jet fan profile;

      2. in-duct smoke detector is located at the start point of the exhaust duct; and

      3. jet fan system shall only operate upon activation of two smoke detectors. This is to minimise false alarms.

   2. The jet fan system shall be provided with a secondary source of power supply through automatic operation of an emergency generator in case of failure of the primary power supply source.

   3. The jet fans shall be distributed at a spacing of 2⁄3 of the tested effective range of each jet fan. The tested effective range of the jet fan shall be taken as the distance up to the point at 0.2m/s of the air-velocity distribution profile.

   4. The minimum headroom for the installation of the jet fan system is 3m.

   5. The interaction of the various components of the jet fan system shall be as follows:

      1. Each group of exhaust fans for each smoke control zone shall be interlocked with its corresponding groups of jet fans for that zone.

      2. If the group of exhaust fans stops/ fails in any smoke control zone, the corresponding group of jet fans in that zone shall stop. But if any of the exhaust fans is still in operation in a particular smoke control zone, all the jet fans in that zone shall continue to operate.

      3. The exhaust fan shall continue to run even if any corresponding group of jet fans fails.

      4. The other groups of jet fans shall continue to run even if any one group of jet fans fails.

      5. If the fire alarm signal is isolated, the exhaust fans and jet fans shall continue to run at high speed. If the fans are manually restarted, both the exhaust fans and jet fans shall continue to run at high speed until they are set to low speed at the field control panel.

   6. The jet fan system shall be independent of any systems serving other parts of the building.

   7. The jet fan system design shall be such that the bulk air velocity induced by the jet fans is sufficient to stop the advance of the ceiling jet within 5m from the fire location in the direction opposite to the induced bulk air flow.

   8. The smoke control sub-panel in each smoke control zone is to be connected to the main smoke control panel, such that any isolation of jet fan system at a particular zone is automatically displayed at the main smoke control panel.

   9. The car park main smoke control panel at the FCC/ Guard house and remote local panel for the supply and exhaust fans shall indicate, by means of indicator lights, whether the fans are on low or high speed. The panels are also required to have the individual group of jet fans indication lights interlocked with the main exhaust fans in the respective smoke control zones.

   10. In the event of failure of the primary source of power supply and subsequent operation of the secondary power supply, the mode of operation of the jet fan system during the fire mode shall follow that prior to the failure of the primary power supply. For example, if the operation of jet fan system in a particular smoke control zone is switched off by the firefighter during fire mode condition and the primary source of power fails, the subsequent operation of the secondary power supply shall be such that the jet fan system remains in the previous fire mode condition, i.e., non-operational mode for that smoke control zone, while the other smoke control zones resume operation.

   11. The jet fan system design shall take into consideration the presence of any down-stand beams and other obstructions that are of depths of more than 1/10 of the car park floor to ceiling height so as to account for any resistance to airflow.

   12. On activation of the jet fan system, the movement of smoke towards the extraction point(s) shall not adversely affect the means of escape and cause smoke to be blown into the lobby area or exit staircases.

   13. The operation of the jet fan system should be such that there are no stagnant areas where smoke can accumulate in the event of fire.

   14. The operation of the jet fan system shall not cause the volume of air movement to be greater than that volume extracted by the main exhaust fans.

   15. There shall be at least one viable approach route (i.e. where acceptance criteria for firefighters are in accordance with Cl.7.4.4g. and Diagram 7.4.4e.(4)-2) for the firefighters to any possible fire location up to a distance of 5m from that fire. As such, information as to the viable approach route shall be displayed at the main fire alarm panel. This can be achieved by arranging the sprinkler control zone to correspond with that of the smoke control zone. Upon detection of the fire within a particular smoke control zone/ sprinkler zone, reference can be made to the display showing the viable approach route for that particular smoke control zone.

5. Wiring arrangement of jet fans

   1. All jet fans shall be connected to the local jet fan control panel in groups of not more than three jet fans.

   2. Each group will be connected by fire-rated cabling.

   3. Each group of jet fans will be protected by a separate MCB (main circuit breaker), with power supply compliant with SS 638, to prevent the failure of all the jet fans at once due to tripping of the main RCB, e.g., due to overloading.

   4. The jet fans shall also be wired in a zigzag configuration and no two consecutive jet fans in a straight line are to be wired in the same group. In the event of failure of one group of jet fans, the next corresponding group will be able to drive the smoke towards the exhaust location to be extracted (see Diagram 7.4.4e.(4) - 1 & 2). Should one group of jet fans fail, all other groups shall still continue to run.

   5. The location of the local control panel for the operation of the jet fans within each zone shall be in a relatively safe area within the zone and be spaced as least 5m apart from the local control panels of adjacent zones. This is to minimise the risk of a fire affecting all the control panels if they be spaced closely together, and thus rendering the ineffectiveness of the jet fan system.

6. Provision of supply air

   1. Supply air to the car park can be provided via mechanised supply air fans or by permanent openings of at least 2.5% of the floor area. Whichever is used, the maximum inlet air speed shall be 2m/s to prevent recirculation of smoke.

   2. The air velocity within escape routes and ramps shall not exceed 5m/s to prevent escapees from being hindered by the air flow.

   3. The replacement air intakes shall face away from any smoke exhaust points and be sited at least 5m apart so as to prevent recirculation of smoke. If the supply and exhaust louvers are located on the same façade of the building, they shall also be sited at least 5m apart.

   4. The replacement air intake shall be located on the opposing end of the smoke exhaust points so that there is no opposing flow between the supply air and the smoke that is drawn towards the exhaust fan.

7. Exhaust fan design

   1. The car park shall be provided with at least 12 air changes per hour during a fire. A lower air change not less than 9 air changes can be permitted provided the acceptance criteria stipulated in the Cl.7.4.4g.(1)(b) can be achieved through fire modelling:

      1. Hot smoke test/ CFD fire modelling
         The effectiveness of the jet fans system design shall be demonstrated using hot smoke test in accordance with Cl.7.4.4j.. The heat release rate of the fuel load for the hot smoke test shall be at least 1MW. The relevant PE or Fire Safety Engineer should decide on the fire location(s) that is (are) deemed most onerous with justification. In addition to the hot smoke test, Computational Fluid Dynamics (CFD) fire modelling will also be required in the following instances:

         1. If air change per hour is smaller than 12.

         2. If there are general goods vehicle or coaches where design fire size exceeds 4 MW (i.e., car fire).

         3. If replacement air is a combination of natural and mechanical means.

         4. If spacing of jet fans is more than 2/3 of the tested effective range.

            The CFD study is to be endorsed by a Fire Safety Engineer (FSE) to verify the conformance of the jet fans system with the acceptance criteria as stipulated in Cl.7.4.4g.(1)(b). The FSE is also required to put up a fire engineering report. Some of the accepted fire modelling software includes FDS, Swift-AVL, Fluent and Pheonics.

      2. Acceptance criteria

         1. Not more than 1000m² of the car park space can be smoke-logged for at least 20 mins, regardless of whether the fire is located within the smoke control zone or across the zone boundaries (Note: After the 20 mins duration, smoke is expected to remain confined within the 1000m² area). Within this smoke-logged area, there shall be at least 1 viable route for the firefighters where the following conditions are satisfied:
            *Smoke temperature shall not exceed 250^oC at a height of 1.7m from floor level.
            *Visibility shall not be less than 5m at a height of 1.7m from floor level.
            These conditions shall commence at a distance of 5m from the fire location in the direction opposite to the induced bulk air flow induced by the jet fans. All other areas outside the smoke-logged area shall be kept substantially free from smoke i.e. smoke temperature not more than 60oC and visibility of at least 25m (Diagrams 7.4.4e (4) - 1 & 2).
            (Note: If hot smoke test is performed, assessment is to be made on the operation of the jet fans system, movement of smoke towards the extraction points and smoke spread. The latter 2 aspects can be generally verified using the above visibility criterion. The temperature criterion need not be verified in view of the nature of the hot smoke test.)

      3. CFD fire modelling input parameters

         1. Fire Size
            The design fire size shall be based on at least 4MW steady-state fire (i.e., car fire). For general goods vehicle, the design fire size shall be based on at least 10MW steady state fire (FSE is expected to provide justification for the bigger fire size other than the car fire).

         2. Type of fire

            The type of fire shall be flaming polyurethane.

         3. Location of fire

            Generally, the fire should be located furthest away from the exhaust points and in between zones. The relevant PE or Fire Safety Engineer should decide on the fire location(s) that is (are) deemed most onerous with justification.

         4. Down-stand beams and other obstruction
            The CFD model shall take into consideration the presence of any down-stand beams and other obstruction that are of depths of more than 1/10 of the car park floor to ceiling height so as to account for any resistance to airflow and turbulence.

         5. Jet fan velocity profile
            Validation model of the velocity profile is to be carried out for a single jet fan. The data from the model shall be compared against physical test data. 
            As such, the jet fan shall be tested for velocity profile by an accredited testing laboratory for comparison with the simulated velocity profile. The test report is to be attached to the Fire Engineering Report. The equation to be used for the deviation between the CFD profile and actual test profile is as follows:
            Equation : Deviation = [(A-B) / B] X 100%
            Where :
            A = distance/width/height from CFD profile
            B = distance/width/height from actual test profile
            The deviation of the distance, width and height of the actual profile from the simulated profile at the various air velocities should be within 10%.

         6. Duration of fire simulation

            The duration of the fire simulation shall be at least 20 mins.

         7. Sprinkler activation
            The model shall assume there is no sprinkler activation for the design fire size specified in Cl.7.4.4g.(1)(c)(i).

         8. Grid resolution
            The grid size to be used in the fire model shall not be larger than 200mm X 200mm X 200mm in the smoke control zone where fire is located and its adjacent zones. Other than these zones, the grid size shall not be larger than 400mm X 400mm X 400mm. Alternatively, the relevant PE or FSE undertakes a grid resolution study to ascertain the appropriate grid size needed for the fire size and smoke flows modelled (e.g., outcome of study showing that additional resolution does not make much of a difference to the results).

         9. Sensitivity study

            A sensitivity study is to be carried out to show the impact of 1 group of jet fan failure nearest the fire on the overall effectiveness of the jet fans system. This study is applicable to both fire modelling and hot smoke test. Notwithstanding the failure of 1 group of jet fans, the acceptance criteria must still be maintained.

   2. The capacity of the exhaust fan and any associated ducting shall be calculated on the basis that the pressure in the car park close to the extract points is equal to the external atmospheric pressure.

   3. Each smoke control zone of the car park shall have its own exhaust fan system. The exhaust fan system in each zone shall be designed to run in at least two parts, such that the total exhaust capacity does not fall below 50% of the required rate of extract in the event of failure of any one part, and that a fault or failure of the exhaust fan system in one zone will not affect the operation of the exhaust fan system in the other zones. The above requirement is also applicable for mechanised supply fan systems, where used.

      (Note: If there is sharing of the exhaust air fans, see Cl.7.4.4c.(2))

   4. The smoke discharge points shall be located such that the smoke extracted from the smoke exhaust fans does not affect any occupied area or means of escape at the level where smoke is discharged.

8. Fire resistance of jet fan system

   The jet fan system, such as the mechanised air supply fans, smoke exhaust fans, jet fans, duct works and wiring shall be capable of operating effectively at 250°C for 2 hours. The fans, ducts and wiring shall be tested in accordance with EN 12101-3, BS 476: Part 24 and SS 299, respectively.

9. Operations and maintenance manual

   An operations and maintenance manual shall be attached. The manual shall contain the roles and responsibilities of the building owner/ operator, the restrictions placed on the building, identification of the sub-systems, servicing and maintenance plan, fault identification, etc. The manual can also be used as a guide for future renovations and changes to the building.

10. Commissioning test

    The Registered Inspector who carries out commissioning test of the jet fans system may make reference to Table 2 of BS 7346 - Part 7 as a guide. When hot smoke test is performed, the PE/ FSE shall use a test fire size of 1MW. Reference may be made to AS 4391 on hot smoke test and PE is advised to make reference on how the test can be prepared and carried out in a proper manner.

1. Acceptable design guidance

   The engineered smoke control system shall be in the form of a smoke ventilation system by natural or mechanical extraction designed in accordance with BR 186, BR 258, BR 368 and other acceptable standards:

2. Sprinkler system

   A building provided with an engineered smoke control system shall be sprinkler-protected.

3. Fire size

   1. Non-industrial buildings

      The capacity of the engineered smoke control system shall be calculated based on the incidence of a likely maximum fire size for a sprinkler controlled fire as recommended in the following table:

      TABLE 7.4.5c.(1) : FIRE SIZE FOR NON- INDUSTRIAL BUILDINGS
      Occupancy (Sprinkler-protected)	Fire Size
      	Heat Output (MW)	Perimeter of Fire (m)
      Shops	5	12
      Shops (fast response sprinklers)	2.5	9
      Offices	1	14
      Hotel Guest Room	0.5	6
      Hotel Public Areas	2.5	12
      Assembly Occupancy with Fixed Seating	2.5	12

   2. Industrial buildings

      The requirements for design fire size are applicable to sprinkler- protected industrial premises (factory and warehouse) without in-rack sprinklers and limited to the design of smoke control system based on Cl.7.4.

      1. Fire growth

         The fire growth can be evaluated by the following generic fire growth curve (also referred to as ‘t2 fire’), that represents the general types of combustible material present within an enclosure:

          

         Q_max = ∝ (t-ti)² ------------------------------------- equation (1)
         where:
         Q_max = heat release rate (kW);
         ∝ = fire growth parameter (kJ/s³);
         t = time (s);
         t_i = time of ignition (s) (taken here as zero)

         The fire growth parameter varies with the fire load density and the fire load configuration factor. However, for purpose of design, fire growth parameter can be generally defined as follows:

         TABLE 7.4.5c.(2)(A) : FIRE GROWTH PARAMETER FOR INDUSTRIAL BUILDINGS
         Fire growth rate	Fire growth parameter (kJ/s3)	Time for Qg = 1MW (s)
         Slow	0.0029	600
         Medium	0.012	300
         Fast	0.047	150
         Ultra fast	0.188	75
         Note: The fire growth rate that is applicable through available literature or standard such as the SFPE Handbook shall be adopted. In the instance where the fire growth rate lies in between the range as stated above, the more conservative fire growth rate is to be used.

      2. Design fire – sprinkler-protected

         1. The heat output of the design fire is assumed to increase according to equation (1) until sprinkler operation is deemed to occur at time t8. Following sprinkler operation, the heat output of the fire is considered to remain constant.

         2. The capacity of the smoke control system shall be based on the fire size that is controlled by activation of 2nd ring of sprinklers.

         3. The operation of the sprinkler system at ts and the corresponding fire size can be determined by hand calculations based on fire engineering principles or the use of fire engineering tools such as FPETool from National Institute of Standards and Technology (NIST). Whichever approach is used, the following design factors governing its calculation are as follows:

            • Rate of fire growth
              The type of fuel load and its configuration in the premises shall govern the rate of fire growth which can be represented using equation (1) and Table 7.4.5c.(2)(a).

            • Sprinkler response time index (RTI)
              The RTI is the thermal sensitivity of the sprinkler and shall be based on the manufacturer’s specification.
              Example:
              Standard response sprinkler – 105m^0.5s^0.5;
              Fast response sprinkler - 50m ^0.5s^0.5;
              ESFR - 26m^0.5s^0.5

            • Temperature rating of sprinkler
              The operating temperature of the sprinklers shall be based on SS CP 52 (e.g., 141°C or 68°C).

            • Ambient temperature
              Room temperature for air-conditioned spaces and non-air conditioned spaces can be taken as 25°C and 30°C, respectively.

            • Ceiling height
              The ceiling height shall be based on the height, measured from the finished floor level to the soffit of the ceiling/ roof.

            • Spacing of sprinkler above fire
              Sprinkler spacing shall be based on SS CP 52 (e.g. 3m by 3m or 4m x 3m).

              Note: The application of FPETool from NIST or any other software in determining the activation time of the sprinkler system and the corresponding fire size has its limitations. Some of the software programs are based on Alpert’s correlations where a number of fundamental assumptions are made such as flat smooth ceilings, unconfined smoke flow, axisymmetric plumes (not near walls or corners), location of detector close to the ceiling, etc. Such assumptions shall thus be taken into consideration when using this tool.

         4. The capacity of the smoke control system shall also take into consideration the possibility of forklift or general goods vehicle on fire along the internal ramps/driveways. For design purposes, the design fire size shall be taken as follows:

            TABLE 7.4.5c.(2)(b)(iv) : VEHICLE DESIGN FIRE SIZE
            Type of vehicle	Design fire size
            Forklift or car	4MW
            General goods vehicle	10MW

      3. Determination of perimeter of fire

         1. Fire perimeter for forklift/car and goods vehicle

            The fire perimeter is used to determine the mass flow rate of smoke. For forklift or general goods vehicle, the perimeter of fire shall be taken as follows:

            TABLE 7.4.5c.(2)(C)(I) : FIRE PERIMETER SIZE
            Type of vehicle	Perimeter of fire
            Forklift or car	5m x 2m
            General goods vehicle	9m x 2.5m

         2. Fire perimeter other than for forklift/car and general goods vehicle

            Other than for forklift/car and general goods vehicle, the following equation is used to calculate the fire perimeter for a square fire of equal sides:

            P = 4(Q_c/Q_r)^0.5 -------------------------------- equation (2)
            where:
            P = fire perimeter (m);
            Q_c = convective heat output = 0.7Q_max (kW);
            Q_r = heat release rate per unit area (kW/m²), see Table 7.4.5c.(2)(c)(ii)

            Where elongated storage configurations such as racking or shelving are used, the fire perimeter is determined using the following equation:

            P = 2[Q_c/(Q_r x d)] --------------------------- equation (3)
            where:
            Q_c = convective heat output = 0.7Q_max (kW);
            Q_r = heat release rate per unit area (kW/m²), see Table 7.4.5c.(2)(c)(ii)
            d = depth of rack (m)

            For purpose of calculating the fire perimeter, the values for Q_r given in Table 7.4.5c.(2)(c)(ii) are used.

            TABLE 7.4.5c.(2)(C)(II) : HEAT RELEASE RATE
            Building Use	Heat release rate per unit area, Qr (kW/m2)
            Industrial	260
            Storage	500

      4. Capacity

         The capacity of an engineered smoke control system shall be capable of handling the demand for smoke exhaust in a worst case scenario.

5. Clear layer

   The design smoke layer base shall be above the heads of people escaping beneath it. The minimum height shall be 2.5m.

6. Smoke reservoir

   1. Smoke reservoirs to prevent the lateral spread of smoke, and to collect smoke for removal, shall be of non-combustible construction capable of withstanding smoke temperatures.

1. -

   2. For cases where smoke is removed from the room of origin, the smoke reservoir size for a smoke ventilation system shall not exceed:

      1. 2000m² for a natural smoke ventilation system; and

      2. 2600m² for a mechanical smoke ventilation system.

1. -

   3. For cases where smoke is removed from a circulation space or atrium space, the smoke reservoir size for a smoke ventilation system shall not exceed:

      1. 1000m² for a natural smoke ventilation system; and

      2. 1300m² for a mechanical smoke ventilation system.

1. -

   4. Reservoir length

      The maximum length of the smoke reservoir shall not exceed 60m.

1. -

   5. Stagnant regions

      Adequate arrangement(s) shall be made in each smoke reservoir for the removal of smoke in a way that will prevent the formation of stagnant regions.

1. -

   6. Perforated ceiling

      For cases where the smoke reservoir is above the false ceiling, the ceiling shall be of perforated type with at least 25% opening.

7. Discharge of smoke

   1. Removal of smoke

      For cases where smoke is removed from a circulation space or atrium space, the rooms discharging smoke into the circulation space/atrium spaces shall either:

      1. have a floor area of not exceeding 1000m² (for natural ventilation system) or 1300m² (for mechanical ventilation system), or

      2. be subdivided such that smoke is vented to the circulation space or atrium only from part of the room with floor area not exceeding 1000m² (for natural ventilation system) or 1300m² (for mechanical ventilation system), that is adjacent to the circulation space or atrium. However, the remainder of the room needs to be provided with an independent smoke ventilation system(s).

1. -

   2. Exhaust points

      The minimum number and siting of exhaust points within a smoke reservoir shall be determined to prevent “plug-holing” effect at the exhaust points. The exhaust point shall comply with the following plugholing equation.

      

8. Limitations

   Owing to practical limitations, a smoke ventilation system shall have:

   1. a maximum mass flow not exceeding 175kg/s; and

   2. a minimum smoke layer temperature of 18°C above ambient temperature.

9. Replacement air

   1. Replacement air shall by natural means be drawn directly from the external space.

   2. The design replacement air discharge velocity shall not exceed 5m/s to prevent the escapees being hindered by the air flow.

   3. Replacement air intake shall be sited at least 5m away from any exhaust air discharge.

   4. Replacement air shall be discharged at a low level, at least 1.5m beneath the designed smoke layer, to prevent fogging up of the lower clear zone.

   5. Where the inlet cannot be sited at least 1.5m below the smoke layer, a smoke curtain or a barrier shall be used to prevent replacement air disrupting the smoke layer.

   6. Where replacement air is taken through inlet air ventilators or door- ways, devices shall be incorporated to automatically open such inlet ventilators and doors to admit replacement air upon activation of the smoke ventilation system.

   7. Where the roller shutters are used as replacement air inlets in the design and installation of an engineered smoke control system or smoke purging system, they shall be of perforated type, having the required effective free area for the effective operation of the engineered smoke control system. Non-perforated type of roller shutters with solid surface shall not be used.

10. Emergency power supply

    The engineered smoke ventilation system shall be provided with secondary source of power supply.

11. Mode of activation

    1. Automatic activation

       1. The engineered smoke ventilation system shall be activated by smoke detectors located in the smoke control zone. Use of smoke detectors for activation shall be carefully designed, so that accidental or premature activation of smoke detectors in a non- fire zone (due to smoke spills or spread from other areas) are avoided.

       2. Provision of activating smoke detectors shall comply with SS 645.

    2. Manual activation

       A remote manual activation and control switches, as well as visual indication of the operation status of the smoke ventilation system, shall also be provided at the FCC. Where there is no FCC, it shall be indicated at the main fire alarm panel.

12. Interlocking with other ACMV systems

    Except for ventilation systems in Cl.5.2.1g. and  Cl.5.2.1h., all other air-conditioning and mechanical ventilation systems within the areas served shall be shut down automatically upon activation of the smoke ventilation system.

13. Standby fans/ multiple fans

    1. Either a standby fan or multiple fans with excess capacity shall be provided for each mechanical smoke ventilation system, such that in the event the duty fan or the largest capacity fan fails, the required smoke extraction rate will still be met. The standby fan shall be automatically activated in the event the duty fan fails.

    2. Fans shall be capable of operating at 250°C for 2 hours.

    3. Protected circuits

       The fans and associated smoke control equipment shall be wired in protected circuits designed to ensure continued operation in the event of fire.

    4. Electrical supply

       The electrical supply to the fans shall, in each case, be connected to a sub-main circuit exclusive thereto after the main isolator of the building. The cables shall be of at least 1-hr fire resistance rating in accordance with SS 299.

14. Smoke ventilation ducts

    1. Smoke ventilation ducts (both exhaust and replacement air ducts) shall be of at least 1-hr fire resistance rating. The rating shall apply to fire exposure from both the interior and exterior of the duct or structure and the duct shall also comply with Cl.7.1.2h..

    2. Where a duct passes through another fire compartment with higher fire rating, the duct shall be constructed to have fire-rating as that of the compartment. Where a duct is installed in a single fire compartment and does not pass through another compartment, smoke control ducts (both exhaust and replacement air ducts) within that compartment need not comply with the 1-hr fire resistance rating requirement subject to the following conditions:

       1. the smoke ventilation ducts (both exhaust and replacement air ducts) are constructed of at least 1.2mm thick galvanised steel sheet;

       2. sprinklers, designed to SS CP 52, shall be provided above and below the entire length of the ducts (regardless of the duct dimensions) to protect the duct surfaces from the effect of water spray through the activated sprinklers; and

       3. the construction and support of the duct shall conform to the appropriate requirements of the duct construction standards contained in ASHRAE Handbook, IHVE Guild books or SMACNA Manuals.

15. Fire damper

    1. Fire dampers shall not be fitted in the smoke ventilation system, except where used in an engineered smoke control system. In such a situation, the fire-smoke dampers shall be constructed in accordance with SS 333.

    2. The damper shall be in closed position during fail-safe mode.

    3. The combination fire and smoke damper, and any duct extension between it and the protected vent shaft, shall be of the same rating as the element of structure.

    4. Sprinkler protection shall be provided to the electric actuator.

    5. The electrical power supply cables to the electric actuator shall be fire resistant.

16. Time taken

    The time for a smoke ventilation system within a smoke zone to be fully operational shall not exceed 60 secs from the time of activation.

17. Natural ventilation

    Natural ventilation shall not be used together with mechanical ventilation.

18. Smoke curtain

    All smoke curtains, where required, unless permanently fixed in-position, shall be brought into position automatically to provide adequate smoke-tightness and effective depth.

19. Obstruction to means of escape

    A smoke curtain, or other smoke barrier, located at any access route forming part of or leading to a means of escape, shall not in its operational position obstruct said escape route.

20. Smoke or chanelling screens

    Where glass walls or panels are being used as smoke screens to form a smoke reservoir or as channelling screens, they shall be able to withstand the design highest temperature.

21. Smoke control equipment

    All smoke control equipment (including smoke curtains) shall be supplied and installed in accordance with BS EN 12101-1, BS EN 12101-3 and BS 7346 Part 7 or equivalent.

22. Engineered smoke control system

    Fixed screen shall be constructed of non-combustible materials capable of resisting the highest design temperatures. Automatic retractable smoke curtains are required to comply with BS 7346 and listed under Product Listing Scheme.

For natural smoke ventilation system, the natural ventilators shall be-

1. in the “open” position in the event of power/system failure; and

2. positioned such that they will not be adversely affected by positive wind pressure.

   Note: Natural ventilators refer to any device e.g., entrance sliding doors or any other mechanised openings for fresh air replacement or smoke venting to external space.

1. 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: 

      1. smoke-free/ fire lift lobbies;

      2. exit staircases; and

      3. 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. 

2. 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.