The LWF Blog

Facilities Management – Voice Alarm Systems – Part 1

November 11, 2016 10:57 am

In this blog series for those who work in Facilities Management and who have a responsibility for fire safety, we have been talking recently about fire alarm systems and how they work. In this blog, we’re going to be looking specifically at voice alarm systems and in what circumstances they might be used.


Voice alarms have increased in popularity since the 1990s, as a means of giving warning to occupants of a building when a fire occurs. Alerting people by voice wasn’t a new idea even then, public address systems had been in use since the 1960s when they were used ‘live’ to give instruction or information to the occupants of buildings, some of which may have been in a fire situation. It was often the case that a traditional fire alarm would sound its bells and that supplementary information could be given over the ‘tannoy’.


However, their use was dependent upon the procedures of the organisation involved and there was no integration between the fire detection system and the public address system.


In recent years, ‘voice alarm system’ has come to mean a system which automatically broadcasts messages or warnings. These systems are designed to assist with meeting the standards required for conventional alarm systems and in some ways are able to exceed those requirements. It is not normally possible to convert an existing fire alarm system and separate public address system into one which would function adequately to satisfy current standards. The voice alarm system must be designed and installed at the same time as the fire alarm system to ensure full compatibility.


One reason why voice alarm systems are becoming more popular as a means of giving warning in case of fire is the increase in phased evacuation. In tall office buildings, phased evacuation is commonplace, with the floor of fire origin and the floor above being evacuated prior to any other necessary floors. The protection provided within the building’s construction (compartment walls, floors etc), means that fire should not pass easily from one floor to another within a set amount of time (usually a minimum of 60-120 minutes fire resistance). The idea behind this is that the affected people can be evacuated, the fire put out and it avoids having to evacuate large numbers of people from floors unaffected by the fire, as well as prioritising an evacuation, based on risk.


This system also means that the way the building is constructed changes. In situations of phased evacuation, less staircases or a narrower stairway width is required than if the entire occupancy of the building had to evacuate simultaneously.


The use of such a voice system means that those people affected will be notified of the need to evacuate immediately and persons working on other floors will receive an alert which reassures them they do not need to evacuate yet and to await further information.


In our next blog, we will continue looking at how voice alarm systems are used and how they came to be in use so frequently in recent years. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.


Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.


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