Voice Alarm Systems for Phased Evacuation: A Retrofit Guide for UAE High-Rises

We covered the headline requirement in our piece on the UAE Fire and Life Safety Code 2023: any residential high-rise above 23 metres now needs phased evacuation, and phased evacuation means a voice alarm system, not a bell. What we did not cover is what actually happens when you take that requirement to a 20-storey occupied residential tower — how the evacuation sequence works floor by floor, what the retrofit touches inside your risers and ceiling voids, and how you get the work done without three months of resident complaints. This is the operational guide.

Why the Bell-and-Run Model Is Dead

Under the old single-stage model, one detector triggers, every sounder in the building goes off at full volume, and every occupant on every floor is expected to move to the stairwell simultaneously. In a 20-storey residential tower with roughly 25-30 units per floor, that means 500 to 600 people converging on two stairwells at the same moment. Fire engineers have known for years that this does not scale — stairwell capacity is fixed, and simultaneous evacuation from height creates queuing on the stairs directly above and below the fire floor, which is exactly where you do not want people standing.

The 2023 code addresses this directly. It requires a voice alarm system capable of addressing individual floors, or small groups of floors, with different messages at different times. The fire floor evacuates immediately. Adjacent floors evacuate on a short delay. Floors further away receive an "alert" tone and a stand-by message, and only move once the stairwell has cleared. This is not a nice-to-have acoustic upgrade — it is a structural change to how your building responds to an alarm, and the 2023 code treats a building without this capability as non-compliant regardless of how good its detection is.

How the Evacuation Sequence Actually Runs

A properly configured phased evacuation follows a standard cascade, and it is worth walking through because it drives every design decision in the retrofit that follows.

Stage one — the fire floor. The zone where the detector or call point activated evacuates immediately with a clear voice instruction: "Fire has been reported on your floor. Leave the building now using the nearest stairway."

Stage two — one floor above. The floor directly above the fire floor evacuates next, typically 30 seconds to two minutes later, since smoke and heat travel upward through shafts and voids faster than they spread laterally.

Stage three — one floor below. The floor directly below follows, usually on a similar short delay, to clear the stairwell before it becomes a bottleneck.

Stage four onward — the remaining floors. Every other floor receives an alert message asking occupants to prepare to evacuate and await further instruction, then is called down in a staggered sequence, typically two floors at a time, until the building is clear. On a 20-storey tower this full cascade usually runs eight to twelve minutes end to end, which is precisely why the delay timings and zone groupings have to be engineered into the panel, not left as defaults.

Every one of those messages, timings, and zone boundaries is a design parameter that a commissioning engineer sets against your building's specific stair, corridor, and unit layout. That is the deliverable your Civil Defence-approved consultant signs off on — not just "a voice alarm was installed."

What the Retrofit Actually Involves

For an occupied building, the retrofit is a cabling and integration project more than an equipment purchase. Four workstreams run in parallel.

Cabling and speaker zones. Fire-rated cable (typically enhanced FP200 or equivalent) has to be run to a new voice alarm speaker in every corridor, lobby, and stairwell landing on every floor, wired into discrete zone loops so each floor — or floor group — can be addressed independently. In most existing towers this means opening ceiling voids in common corridors floor by floor; it rarely requires access inside individual apartments, which is the single biggest factor in keeping resident disruption low.

The voice alarm control equipment (VACIE). A dedicated voice alarm control and indicating panel is installed alongside or integrated with the existing fire alarm panel in the fire command centre, with amplifiers sized for the total speaker load plus spare capacity for future zones.

BMS and fire panel integration. The voice alarm panel has to interface with the existing fire alarm control panel so zone activation triggers the correct message automatically, and with the BMS so lift homing, smoke damper closure, and stairwell pressurisation fire fans are sequenced against the same evacuation cascade rather than firing independently.

Commissioning and testing. Every zone is tested individually for intelligibility (measured against STI — Speech Transmission Index — targets, typically 0.5 or higher) and for correct cascade timing, then the full system is tested end to end with the Civil Defence-approved consultant present before the certificate is issued.

Sequencing the Work Without Emptying the Building

The retrofit budget of AED 150,000 to AED 300,000 for a 20-storey residential tower assumes the building stays occupied throughout. Sequencing is what makes that possible, and it is where most projects either run smoothly or turn into a resident-relations problem.

Work floor by floor, not system-wide. Contractors should complete cabling, speaker installation, and zone termination on one floor's common areas — typically a half-day to a full day per floor for corridor work — before moving to the next, rather than opening every ceiling void in the building simultaneously. This keeps disruption localised and lets you give residents on that floor specific, short-notice warning rather than a building-wide notice that unsettles everyone for weeks.

Schedule corridor and riser work during standard daytime hours, and complete plant room and fire command centre work — where the VACIE panel and amplifiers are installed — outside those hours where possible, since that work does not touch occupied floors at all. A fire watch must be maintained on any floor where the existing alarm zone is taken offline for rewiring, and residents need written notice of exactly which days their floor's detection coverage is temporarily reduced. Building managers who skip the fire watch step are the ones who end up with a Civil Defence non-conformance notice mid-project, which stalls the whole retrofit.

Finally, commission and test floor by floor as each zone is completed, rather than waiting until the whole building is wired to run a single test. This means each floor's voice alarm zone is live and functioning as soon as it's finished, rather than the entire building running on a partially-tested system for the two to three months a full retrofit typically takes.

Tracking the Retrofit and the Certificate

A voice alarm retrofit generates a lot of paperwork that Civil Defence will ask for later: the zone design drawings, the cable schedule, the STI test results per zone, the BMS integration test log, and the final commissioning certificate from your approved consultant. If any one of those documents is missing when your next annual audit comes around, the auditor has no way to confirm the system that was installed is the system that was certified.

This is exactly the kind of evidence trail Herman is built to hold. Rather than a folder of PDFs split across the contractor, the consultant, and your own maintenance team, HermanWa keeps the retrofit project — floor-by-floor completion status, test certificates, the final commissioning sign-off — in the same file as your detection upgrades, sprinkler inspections, and audit history. When the Civil Defence auditor asks for proof that your phased evacuation system was designed, installed, and tested to the 2023 code, you are not searching for it. It is already attached to the building.

— The HermanWa Team