Specification 31 Fire and smoke control systems in buildings containing atriums
S31C1
Scope
2019: Spec G3.8: 1
This Specification sets out the requirements for the design and operation of systems of fire and smoke control in buildings containing an atrium.
Automatic fire sprinkler system
S31C2
General requirement — automatic fire sprinkler system
2019: Spec G3.8: 2.1
A sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification 17 must be installed in every building containing an atrium, except where varied or superseded by this Specification.
S31C3
Roof protection
2019: Spec G3.8: 2.2
- less than 12 m above the floor of the atrium or the floor of the highest storey where the bounding construction is set back more than 3.5 m from the atrium well if a Class 2, 3, 5 or 9 part of a building is open to the atrium; or
- less than 20 m above the floor of the atrium or the floor of the highest storey where the bounding construction is set back more than 3.5 m from the atrium well if a Class 6, 7 or 8 part of a building is open to the atrium.
S31C4
Atrium floor protection
2019: Spec G3.8: 2.3
S31C5
Sprinkler systems to glazed walls
2019: Spec G3.8: 2.4.1 – 2.4.5
- On the atrium side of the glazing — to all glazed walls which are set back more than 3.5 m from the atrium well.
- On the atrium side of the glazing — to all glazed walls which are not set back, or are set back 3.5 m or less, from the atrium well, for all levels which are less than—
- 12 m above the floor of an atrium or the floor of the highest storey where the bounding wall is set back more than 3.5 m from the atrium well if a Class 2, 3, 5 or 9 part of the building is open to the atrium; or
- 20 m above the floor of an atrium or the floor of the highest storey where the bounding wall is set back more than 3.5 m from the atrium well if a Class 6, 7 or 8 part of the building is open to the atrium.
- On the side of the glazing away from the atrium well — to all glazing forming part of the bounding wall at each storey.
- on the atrium side of the glazing—
- 0.25 L/s.m2 where glazing is not set back from the atrium well; or
- 0.167 L/s.m2 where glazing is set back from the atrium well; and
- on the side away from the atrium well — 0.167 L/s.m2.
- Where the bounding walls are set back less than 3.5 m from the atrium well — wall wetting of a part not less than 6 m long for a height of not less than—
- 12 m above the floor of an atrium or the floor of the highest storey where the bounding wall is set back more than 3.5 m from the atrium well if a Class 2, 3, 5 or 9 part of the building is open to the atrium; or
- 20 m above the floor of an atrium or the floor of the highest storey where the bounding wall is set back more than 3.5 m from the atrium well if a Class 6, 7 or 8 part of the building is open to the atrium.
- Where the walls are set back 3.5 m or more from the atrium well — wetting of a part not less than 12 m long on one storey.
S31C6
Stop valves
2019: Spec G3.8: 2.5
Smoke control system
S31C7
General requirements — smoke control system
2019: Spec G3.8: 3.1
Except where varied or superseded by this Specification, mechanical air-handling systems in a building containing an atrium must comply with AS 1668.1.
S31C8
Operation of atrium mechanical air-handling systems
2019: Spec G3.8: 3.2
Mechanical air-handling systems serving an atrium must be designed to operate so that during a fire—
- a tenable atmosphere is maintained in all paths of travel along balconies to required exits during the period of evacuation; and
- smoke exhaust fans serving the atrium are only activated when smoke enters the atrium; and
- central plant systems do not use the atrium as a return air path; and
- central plant systems which use return air paths remote from the atrium—
- cycle to the full outside air mode; and
- stop supply air to the fire affected storey or fire compartment; and
- continue to fully exhaust the fire affected storey or fire compartment and reduce the exhaust from other storeys or fire compartments by at least 75%; and
- continue to supply air to fire compartments or storeys other than the fire affected storey or fire compartment; and
- fans performing relief or exhaust duty from the atrium stop normal operation; and
- floor by floor, or unitary, air-handling plant serving a single fire compartment or storey—
- ceases normal operation in the fire affected storey or fire compartment; and
- commences full relief or exhaust from that fire affected storey or fire compartment; and
- continue to supply air to fire compartments or storeys other than the fire affected storey or fire compartment.
S31C9
Activation of smoke control system
2019: Spec G3.8: 3.3
- operation of an automatic fire alarm; or
- operation of the sprinkler system; or
- a manual start switch.
- in the fire control room; or
- in the emergency control centre (if any); or
- adjacent to the sprinkler control valves; or
- incorporated in the Fire Indicator Panel.
S31C10
Smoke exhaust system
2019: Spec G3.8: 3.4
A smoke exhaust system serving an atrium must be designed on the basis of—
- the sprinkler system limiting the size of a fire to—
- a smoke plume reaching a level 3 m above the highest storey having a path of travel to a required exit along a balcony bounding the atrium well, and not less than—
- 12 m above the floor of an atrium or the floor of the highest storey where the bounding wall is set back more than 3.5 m from the atrium well if a Class 2, 3, 5 or 9 part of the building is open to the atrium; or
- 20 m above the floor of an atrium or the floor of the highest storey where the bounding construction is set back more than 3.5 m from the atrium well if a Class 6, 7 or 8 part of the building is open to the atrium; and
- the smoke exhaust system discharging smoke at a rate of not less than that shown in Figure S31C10 for the appropriate height of smoke plume and fire size—
- from the top of the atrium; or
- horizontally, where calculations of wind velocity induced pressure profiles for the building verify that the exhaust system will operate effectively for all wind directions.
S31C11
Upward air velocity
2019: Spec G3.8: 3.5
Notwithstanding S31C10(c), the average upward air velocity in the atrium, due to the required smoke exhaust quantity must—
- be not less than 0.2 m/s at any level over an 18 m height above the floor of the atrium; and
- not exceed the following maximum velocities in atriums of constant cross sectional plan area:
- For occupancy classification qualifying for 1.5 MW fire size — 3.5 m/s.
- For occupancy classifications qualifying for 5 MW fire size — 5 m/s.
S31C12
Exhaust fans
2019: Spec G3.8: 3.6
S31C13
Smoke-and-heat vents
2019: Spec G3.8: 3.7
Notwithstanding S31C12, automatic vents complying with AS 2665 may be used, except where a Class 6 part of a building adjoins the atrium, in lieu of exhaust fans provided that—
- the height from the atrium floor to the bottom of the highest vent is not more than 12 m; and
- the vents are fitted with a remote manual operation switch located adjacent to the sprinkler control valves or incorporated in the Fire Indicator Panel.
S31C14
Make-up air supply
2019: Spec G3.8: 3.8
- openings directly from the outside air to the atrium and located as close as practicable to the lowest level of the atrium; or
- ducts from the outside air to the atrium which deliver air as close as practicable to the lowest level of the atrium and, where passing through any other fire compartment having an FRL of at least 60/60/60; or
- a combination of (a) or (b).
Fire detection and alarm system
S31C15
General requirements—fire detection and alarm system
2019: Spec G3.8: 4.1
S31C16
Smoke detection system
2019: Spec G3.8: 4.2
Smoke detection within an atrium—
- must be provided within all outside air intakes and at individual floor return air intakes of all air-handling systems to initiate automatic fire mode operation, and where applicable, comply with the restart facilities in AS 1668.1; and
- must operate at an obscuration level not greater than 0.5% per metre with compensation for external airborne contamination as necessary; and
- must sample air within the atrium and in storeys where the bounding wall is set back more than 3.5 m from the atrium well; and
- must be calibrated to compensate for smoke dilution where sampling occurs within return air path common to more than one room; and
- may incorporate beam type detectors to sense smoke in an atrium in a Class 5, 6, 7 or 8 building with an effective height of not more than 25 m if the beam detectors are—
- located at intervals of not more than 3 storeys; and
- arranged to scan at 90 degrees orientation to adjacent beam units.
S31C17
Smoke detection in spaces separated from the atrium by bounding walls
2019: Spec G3.8: 4.3
S31C18
Alarm systems
2019: Spec G3.8: 4.4
- Alert building management when abnormal smoke levels of 0.03% obscuration per metre are detected.
- Initiate a second alarm to management and start all smoke control systems including pressurisation of escape routes when smoke levels of 0.07% obscuration per metre are detected.
- Automatically call the fire brigade, activate the emergency warning and intercom system, and de-activate all plant not necessary for fire safety within the building when smoke levels of 0.09% obscuration per metre are detected.
Additional requirements
S31C19
Emergency warning and intercom systems
2019: Spec G3.8: 5
A building containing an atrium must be provided with an emergency warning and intercom system which—
- complies with AS 1670.4; and
- incorporates visual warning devices that—
- operate upon the evacuation signal; and
- display the word “EVACUATE” in red with letters conforming with the requirements of the Deemed-to-Satisfy Provisions of Part E4 for exit signs.
S31C20
Standby power system
2019: Spec G3.8: 6
- be connected automatically if the normal power supply fails; and
- if located within the building, be separated from the remainder of the building by an enclosure with an FRL of at least 120/120/120; and
- be connected to the safety systems by means of cabling complying with C3D14(3).
- a single medium voltage supply taken from an electricity substation situated within, or adjacent to, the building concerned where the power supply to the substation consists of two or more high voltage cables each taking electricity from separate transformers; or
- two or more medium voltage supplies each taking electricity from separate electricity substations situated—
- outside the building concerned; and
- at a suitable distance from each other; or
- a single medium voltage supply taken from an electricity substation together with an electricity generating plant capable of—
- generating a medium voltage supply; and
- starting and taking the required electrical load within a period of not more than 30 seconds from the time of normal supply failure.