Part E2 Smoke hazard management

E2.1 to E2.3 and EP2.1 and EP2.2

Where a solution is proposed to comply with the Deemed-to-Satisfy Provisions, except in buildings containing atriums, compliance with E2.1 to E2.3 achieves compliance with EP2.1 and EP2.2.

In addition to achieving compliance with E2.1 to E2.3, to achieve compliance with EP2.1 and EP2.2 buildings with atriums must also comply with Part G3.

Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2.2(3) and A2.4(3) as applicable. (See commentary on Part A2).

E2.1(a), E2.2 and E2.3 do not apply to open-deck carparks or open spectator stands. EP2.2 does not apply to such buildings because the smoke and hot gases can vent naturally.

The Deemed-to-Satisfy Provisions of Part E2 do not apply to small Class 8 electricity network substations, located in a multi-classified building. These smaller substations are usually located within a "host" building and the associated electrical equipment has its own sensitive dedicated systems that provide a rapid response signal to a central control room that is constantly staffed.

Under E2.1(b), the E2.2 and E2.3 provisions regarding smoke exhaust systems and smoke-and-heat vents do not apply to small areas used for short periods.

A small area will be easily evacuated before smoke build-up and if the area is only used for short periods, the risk of occupants being trapped in it during a fire is low.

Class 2–9 buildings must comply with E2.2(b), (c) and (d), which cover the fire mode operation of air-handling systems so that they do not contribute to the spread of smoke during a fire. This assists to maintain the basic smoke integrity of the fire compartments.

In addition to E2.2(b), (c) and (d), Class 2–9 buildings must comply with the requirements of Table E2.2a, which provides some general and specific strategies for smoke hazard management.

In addition to E2.2(b), (c) and (d) and Table E2.2a, Class 6 and Class 9b buildings must comply with the requirements of Table E2.2b, where applicable, which provides some general and specific strategies for smoke hazard management.

E2.2(b) requires that an air-handling system that is not part of a smoke hazard management system be designed and installed with suitable strategies to ensure that, during a fire, it does not:

• recycle air (and therefore smoke) from one fire compartment to another; or
• otherwise contribute to the spread of smoke between fire compartments.

The effect of E2.2(b)(i) is that in a fire, an air-handling system must either operate as a smoke control system in accordance with AS 1668.1 (as specified in E2.2(b)(i)) or shut down (as specified in E2.2(b)(ii)).

A smoke purging system, in accordance with AS 1668.1, is allowable in buildings not covered by the general provisions in Table E2.2a, and, in some instances, in conjunction with other measures in accordance with Table E2.2a.

An air-handling system not designed as a smoke control system must comply with the requirements set out in E2.2(b) as follows:

• Automatic smoke dampers—E2.2(b)(ii)(A)

  Where the air-handling system is shut down in fire mode, it must incorporate automatic smoke dampers where the ducts penetrate any fire barriers.

  This requirement may apply to an air-handling system which supplies outside air to a group of residential sole-occupancy units.

• System shut down—E2.2(b)(ii)(B)

  The air handling system must shut down, and smoke detectors must automatically activate smoke dampers.

• Class 2 and Class 3 buildings

Sole-occupancy units in Class 2 and Class 3 buildings are, under E2.2(b), regarded as separate fire compartments.

Air-handling systems, other than one in a carpark, serving more than one fire compartment covered by Sections 5 and 6 of AS 1668.1 must be designed and installed in compliance with those sections of the Australian Standard. This will restrict the spread of smoke between fire compartments.

Provisions on the operation of carpark ventilation systems during a fire in the carpark are included under the general provisions in Table E2.2a.

An AS 1668.1 system for zone pressurisation and automatic air pressurisation for fire-isolated exits must be controlled by a smoke detection and alarm system installed in compliance with Specification E2.2a. Activation of these systems also requires the activation of a building occupant warning system.

E2.3 states that certain factors may need additional smoke hazard management measures.

E2.3 reinforces the need for careful consideration and sound professional judgement in the application of the smoke hazard management provisions of the BCA.

Deemed-to-Satisfy Provisions—Tables E2.2a and E2.2b

EP2.1 requires automatic warning on the detection of smoke in buildings having sleeping accommodation, so that occupants may be alerted to the fire hazard. EP2.2, in terms of maintaining safe conditions in any evacuation route, deals with the period of time it would take occupants to evacuate that part of the building.

Table E2.2a provides smoke hazard management strategies structured to help application to buildings of mixed classification. In the case of a multi-classified building, each classifiable part must comply with the relevant provisions for its classification. Certain Class 6 and Class 9b parts of buildings must also comply with the specific provisions in Table E2.2b.

Where zone pressurisation systems are specified in various locations in Table E2.2a to be in accordance with AS 1668.1, the provision states that zone pressurisation systems only apply between vertically separated fire compartments and not horizontal fire compartments.

Fire-isolated exits enable the safe evacuation of occupants, and also aid fire brigade access. Smoke must not unduly affect the conditions in such exits during an evacuation.

To minimise smoke intrusion, the exits may need to be pressurised with outside air for the entire exit route. See the following examples. Alternatively, the exits may be provided with open access ramps or balconies from which smoke can vent naturally.

In buildings more than 25 metres in effective height, tenable conditions need to be maintained in the fire-isolated exits and, where practicable, in other parts of the building to enable the staged evacuation of occupants.

Occupants of such buildings may continue to occupy compartments remote from the fire for an extended time before evacuation. Accordingly, suitable measures must be adopted to minimise the spread of smoke from the fire-affected compartment to non-affected compartments by way of a number of potential leakage paths.

These paths include lift shafts, air-handling ducts, services risers, building penetrations, spandrels, and the like, through which smoke can be driven by buoyancy, expansion, stack and wind effects, and air-handling systems.

In order to minimise the spread of smoke, a zone pressurisation system is considered necessary in buildings more than 25 metres in effective height. This does not apply to the residential parts of a building in view of:

• the alternative protection provided by the fire compartmentation of sole-occupancy units;
• separation of public corridors by bounding construction; and
• division of such corridors by smoke-proof walls into lengths of not more than 40 metres (see C2.14).

Additionally, this requirement does not apply to a building that contains only one single fire compartment containing a Class 5, 6, 7b, 8 or 9b part (or a combination of these classes in the same fire compartment) in an otherwise Class 2, 3, 9a or 9c building. Reference to a Class 2, 3, 9a or 9c building does not include a building that also contains a Class 7a carpark (see Figure E2.2a). The reasons for this exemption are:

• the provision of a zone pressurisation system is considered inappropriate for a single compartment in a building; and
• any single fire compartment Class 9b building or Class 6 building with a floor area greater than 2000 m² is also subject to the provisions of Table E2.2b, ensuring that smoke hazard management considerations are applied; and
• to require compliance could create an anomaly with the exemption of sporting complexes, including gymnasiums and swimming pools from required smoke hazard management measures under Table E2.2b.

Notwithstanding the above, a smoke detection and alarm system must be provided in residential and health-care buildings to provide early warning to occupants who may be asleep, confused, or non-ambulatory and dependent on assistance.

Figure E2.2a Zone pressurisation concession

Table E2.2a provisions are additional to other safety provisions for buildings with an effective height of more than 25 metres.

In buildings less than 25 metres in effective height, the necessary levels of protection may be achieved by measures other than zone pressurisation, depending on the Class and rise in storeys of the building.

In buildings other than health-care buildings, zone pressurisation may be substituted by either stairway pressurisation, smoke detection, or sprinkler protection. The rise in storeys before which the provisions become applicable depends on the building’s classification and use.

The above measures do not apply to the residential parts of a building because of the passive protection provided to such parts. However, where one or more fire-isolated exits join residential and non-residential parts, other than open-deck carparks, the fire-isolated exits must either be pressurised, or the non-residential parts provided with smoke detection or sprinkler protection. This is necessary to compensate for the potential additional hazard associated with the particular mix of Classes.

In health-care buildings, zone pressurisation may be substituted by a sprinkler system, providing residential sprinkler heads are used in patient care areas. The fast response of residential sprinkler heads promotes life safety by limiting fire growth and smoke development. Where zone control is not adopted, the air-handling systems must generally be shut down not only to maintain the integrity of the smoke and fire compartmentation, but also to minimise the spread of smoke within the fire-affected compartment.

Notwithstanding the above, a smoke detection and alarm system must be provided in residential and health-care buildings.

These provisions set out the smoke hazard management measures for large isolated Class 7 or 8 buildings subject to the requirements of C2.3(a) with a floor area of 18 000 m² or less and a volume of 108 000 m³ or less. Such buildings are required to have:

• a sprinkler system (see Specification E1.5 for details) and be provided with perimeter vehicular access complying with C2.4(b);
• an automatic fire detection and alarm system (see Clause 7 of Specification E2.2a for details);
• an automatic smoke exhaust system (see Specification E2.2b for details);
• automatic smoke and heat vents (see Specification E2.2c for details); or
• natural smoke venting (see Table E2.2a for details).

These provisions set out the smoke hazard management measures for large isolated Class 5 to 9 buildings subject to the requirements of C2.3(b) having a floor area exceeding 18 000 m² or having a volume exceeding 108 000 m³.

Such buildings are required to have:

• where there is a ceiling height of 12 metres or less, either a specified automatic smoke exhaust system (see Specification E2.2b for details), or an automatic smoke-and-heat ventilation system (see Specification E2.2c for details); or
• where there is a ceiling height of more than 12 metres, a specified automatic smoke exhaust system (see Specification E2.2b for details).

Roller shutters and doors can be used for smoke venting purposes in accordance with the table if they are “readily openable”. A building proponent must satisfy the appropriate authority that such roller shutters and doors achieve the “readily openable” requirement.

However, if the openings are also used for egress purposes, they must also comply with the requirements of relevant provisions such as D2.19 and D2.21.

A carpark ventilation system is consistent with the treatment of miscellaneous air-handling systems in AS 1668.1. Accordingly, the electric power and control cabling for a carpark ventilation system need not be fire rated.

Likewise, a concession is granted to allow fans with metal blades suitable for operating at normal temperatures to be used instead of fans required to operate at elevated temperatures as required by Clause 4.8.1 of AS 1668.1.

To make sure that the manual override provision of Clause 5.5.3 of AS 1668.1 is not subject to the control of any general installation main switches, the power supply arrangement must comply with AS 3000.

The provisions for basements are more stringent due to the special problems they pose for evacuation, search and rescue, and firefighting operations.

As the total floor area of the basement increases to above 2 000 m², certain minimum measures have been stipulated. In basements with three or more below ground storeys, a sprinkler system is considered necessary.

The provisions of this Part, as well as Part G3, apply to atrium buildings.

The provisions of Table E2.2b are additional strategies which only apply to certain Class 6 and Class 9b buildings where there is a high risk that occupants may not be able to safely evacuate the fire-affected compartment. This risk may be due to factors such as:

• building design;
• function;
• usage;
• fire load; or
• nature of occupancy.

Occupants of such buildings are also not necessarily familiar with the building or the procedures for evacuation.

Table E2.2b addresses requirements under EP2.2 in terms of maintaining safe conditions in any evacuation route within the fire-affected compartment of Class 6 and Class 9b buildings, for the period of time it would take occupants to evacuate that part of the building.

There are specific provisions for large Class 6 buildings in Table E2.2b for the installation of either an automatic smoke exhaust system or automatic smoke-and-heat vents to control smoke during a fire. These apply to the whole fire compartment where the floor area of the Class 6 part of the fire compartment is more than 2 000 m².

There are specific concessions that vary these requirements. These are—

• for buildings where the floor area of the fire compartment does not exceed 3 500 m², it is permitted to install—
  • an automatic smoke detection and alarm system in lieu of a smoke exhaust or smoke venting system if the building is single storey; or
  • a sprinkler system if the building has a rise in storeys of not more than 2.

• for single storey shops with a floor area less than 2 000 m² (within a larger fire compartment) which have a main entrance opening to a road or open space and are smoke separated from the fire compartment. See Example 1.

• for another part of the building with a different classification (i.e. other than Class 6) which is smoke separated, including openings, junctions and joints of building elements, etc., from the Class 6 part.

Figure E2.2b(1) Plan of shopping centre for Example 1

The specific smoke hazard management provisions for Class 6 buildings containing shops and an enclosed common walkway or mall are similar. Where such a building has a fire compartment with a floor area of more than 2 000 m², an automatic smoke exhaust system or an automatic smoke-and-heat vent system to control smoke during a fire is required.

However, where a single storey shop does not open onto the mall and its main public entrance opens to a road or open space, it does not need to have any smoke exhaust or smoke venting, if its floor area does not exceed 2 000 m². This is similar to the concession for a shop in a building which does not contain a mall.

Another concession applies to shops that open onto the mall. They do not need to have any smoke exhaust or smoke venting system if their individual floor areas are less than 1 000m².

A concession is also available for another part of the building with a different classification (i.e. other than Class 6) which is smoke separated, including openings, junctions and joints of building elements, etc., from the Class 6 part.

In a Class 6 building containing a mall, a sprinkler system can also be used in lieu of a required automatic smoke exhaust system or an automatic smoke-and-heat vent system, if the floor area of the whole fire compartment is not more than 3 500 m².

Figure E2.2b(2) Plan of shopping centre for example 2

Assembly buildings cover a wide range of uses with varying degrees of hazards. Table E2.2b addresses some of the uses to enable greater uniformity in the treatment of the buildings or parts of buildings. It provides for assembly buildings generally, except for certain low hazard occupancies which have been exempted from compliance.

Certain Table E2.2b provisions for assembly buildings do not apply to schools, apart from the automatic shutdown of air-handling systems in lecture theatres. This is because such buildings may have alarm systems with which the occupants are familiar, and the occupants are usually under a sufficient level of control to enable quick and orderly evacuation.

Concessions are granted for sporting complexes, excluding indoor stadiums with total spectator seating of more than 1000, principally because the risk levels are not high, particularly with regard to open-air complexes. Buildings used solely for religious worship are also exempt.

The Table E2.2b provisions for smoke exhaust or smoke-and-heat vents are applicable to fire compartments having a floor area of more than 2 000 m², except that certain concessions apply to low rise buildings.

If the floor area of the fire compartment is not more than 5 000 m², smoke extraction need not be provided if the building has a rise in storeys of two or less, and a smoke detection and alarm system, or a sprinkler system is installed.

The Table E2.2b provisions apply to all nightclubs, discotheques and the like, regardless of the floor area, in recognition of the high hazards generated by such factors as:

• occupant density;
• access control;
• indoor environment;
• quantity and location of soft furnishings;
• whether or not smoking is permitted; and
• occupant behaviour.

The Table E2.2b provisions for exhibition halls which are used for trade displays and the like are based on them having hazards similar to those for shopping centres and indoor markets.

The Table E2.2b provisions only apply to those theatres and public halls which are considered a high hazard occupancy due to the potential fire load associated with the stage and backstage areas and/or rigging lofts. Under Part H1, such theatres and public halls are also required to be sprinkler protected or have the stage and backstage areas separated from the audience by a proscenium wall.

The Table E2.2b provisions for these occupancies are similar to those for assembly buildings. The provision for automatic shutdown of air-handling systems (which do not form part of a smoke management system) is applicable in all such buildings, including those serving school lecture theatres not more than 2 000 m² in area.

Table E2.2b includes provisions for general assembly buildings not covered elsewhere. Museums and art galleries with fire compartments in excess of 2000 m² are covered by these provisions.