Audio Visual Design Guidelines

Evacuation and life safety

36 views November 19, 2019 aetm 0

The national building and fire codes in Australia and New Zealand require that emergency and evacuation messaging can be clearly heard by the population of a building. 

Whilst other forms of alerting system will apply to some projects, it is most common to encounter an EWIS (Emergency Warning and Intercommunication System). Both Australia and New Zealand reference AS1670.4; the deviations identified in NZS 4512 concern the Fire trade, not AV.

This is a life safety system, so:

  • It is critical for designers to liaise closely with each project’s fire engineers to understand, allow for and implement strategies which ensure the building can be certified. The approach taken on any previous project cannot be assumed to be automatically applicable.
  • We must appreciate our sound systems are competing sound systems under AS1670.4 and may need to be shut down when any emergency warning system is broadcast.
  • If a combined EWIS/general PA is considered, AS1670.4:2015 requires loudspeakers to comply with AS7240.24. At the time of publication, only those speakers marketed specifically for EWIS comply, though most speaker manufacturers were evaluating certification requirements.

While this document cannot predict any certifier or fire engineer’s opinion, our ‘competing’ PA systems will often be evaluated as compliant on the following basis:

  • Auditoria, lecture theatres, large spaces (average SPL >75dB(A) is likely)
    • Fire contractor provides a failsafe EWIS mute line from their system 
      • When an alarm is triggered, or the line breaks the trigger changes state. 
      • This trigger may be dry (relay) or wet (voltage) depending on local circumstances.
    • AV system mutes audio on change of state.
      • Occasionally we are required to fully shutdown the amplifiers
  • Meeting and smaller rooms (average SPL≤75dB(A) is likely)
    • System is configured so average SPL is well below the EWIS – generally at least 10dB

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