Fire alarm systems: design the response, not only the devices

A fire alarm system is a chain with four links: detect the condition, alert the people in the building, tell the responsible team what is happening and where, and have them act. Specifications tend to concentrate on the first link and the device schedule, which is why the weakest link is usually one of the other three.

Detection is one part of the chain

Detection type and placement follow the occupancy and the building fabric — what is stored, how high the ceilings are, how air moves. Zoning should follow how people would actually evacuate, not how the floor plan is drawn, because a zone that does not match an evacuation route makes a panel indication harder to act on. Sounder and beacon coverage has to be checked against the real noise level of each area.

Zoning creates useful information

The response is the part to write down. Who is called, who sweeps which area, who meets the fire service, who confirms the building is clear. Commission the cause-and-effect behaviour end to end and demonstrate it to the people who will act on it, then test it on a schedule. A system nobody has practised with is a system that will be improvised around on the day.