• • • SAFETY IN ENGINEERING• • •
WHEN THE SAFE ROUTE IS NO LONGER SAFE: THE CASE FOR ADAPTIVE
EMERGENCY ESCAPE LIGHTING BY JACK ADAMS,
TECHNICAL AND ACCREDITATION MANAGER, LIGHTING INDUSTRY ASSOCIATION
S
afety engineering is built around a simple principle: we should not only consider how a system is intended to operate, but how it might behave when circumstances go wrong. Emergency lighting is no exception. Traditionally, an emergency escape lighting system is designed around predetermined escape routes. Luminaires illuminate those routes and illuminated safety signs provide occupants with clear directional information towards exits and places of safety. This approach has protected building occupants for decades and remains fundamental to life safety. But there is an important question for engineers and building operators to consider: what happens when the designated escape route itself becomes unsafe?
A fire, smoke, structural damage or another developing hazard can make a normally safe route unusable. Yet a conventional static exit sign cannot understand that circumstances have changed. It continues to provide the same instruction. Adaptive Emergency Escape Lighting Systems (AEELS) offer another layer of protection. AEELS are capable of responding to changing circumstances. Rather than simply providing fixed directional information, an adaptive system can modify escape directions and increase the conspicuity of emergency signage, with the potential also to alter lighting levels. Systems may operate according to a predefined scenario when evacuation begins or respond as
conditions change during the incident. The significance of this becomes clearer when we examine real emergencies. On 20 February 2003, a fire broke out at The Station nightclub in Rhode Island, USA. Pyrotechnics ignited polyurethane foam around the performance area and the fire developed extraordinarily quickly. Smoke was visible at the main entrance in little more than a minute. Within around 90 seconds, conditions in parts of the building had exceeded accepted survivability limits. One hundred people died. The subsequent NIST (National Institute of Standards and Technology) investigation identified a critical issue with the evacuation. Although other exits existed, approximately two-thirds of the occupants attempted to escape through the main entrance, the route through which many had entered the building. Before 90 seconds had elapsed, a crowd crush at that entrance had almost entirely disrupted evacuation through it.
The tragedy cannot, of course, be reduced to emergency signage. NIST identified multiple contributing factors and made recommendations covering areas including sprinklers, materials, evacuation, codes and emergency response. Nevertheless, its findings demonstrate an important principle for safety engineering: the escape route that looks correct in the plan, may not remain the safest route during a real emergency.
NIST subsequently recommended increasing the factor of safety applied to evacuation, including calculating required exits on the assumption that at least one exit may be inaccessible during an emergency. This is precisely the type of problem that adaptive emergency escape lighting seeks to address.
14 ELECTRICAL ENGINEERING • OCTOBER 2026
Imagine a building with several available escape routes. A developing incident makes one route dangerous because of smoke or fire. Instead of continuing to direct occupants towards that route, an appropriately designed AEELS could change the information displayed by directional signs, identifying the affected route as unavailable and directing occupants towards an alternative. This does not replace good building design, adequate exits, fire detection, compartmentation, evacuation planning or properly designed conventional emergency lighting. AEELS should instead be viewed as another tool within the wider life-safety strategy. Importantly, adaptive emergency lighting is now recognised within the European emergency lighting framework. BS EN 1838:2024 states that where a premises operator needs the ability to redirect occupants away from specific emergency escape routes, an AEELS complying with CEN/TS 17951 should be used.
BS EN 50172:2024 similarly recognises both adaptive and non-adaptive emergency escape lighting systems. For engineers, this represents an important evolution in how we think about emergency lighting.
A building is not static during an emergency.
Fire spreads. Smoke moves. Routes become compromised. Occupants behave unpredictably. The safest direction at the beginning of an incident may not be the safest direction sixty seconds later. Emergency safety systems increasingly have the capability to recognise and respond to that reality. The question is, therefore, moving beyond simply “Can people see the escape route?” Increasingly, we should also be asking: “Are we still showing them the right escape route?”
www.thelia.org.uk electricalengineeringmagazine.co.uk
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