ISO/TR 25743:2010 — Lifts (Elevators): Use for Evacuation During Emergencies

1. Scope and Risk Assessment Framework of ISO/TR 25743

ISO/TR 25743:2010 investigates the risks and hazards associated with using lifts (elevators) for the evacuation of persons during building emergencies. Historically, lifts have been explicitly excluded from use during fires and other emergencies based on concerns about power loss, smoke ingress, and passenger entrapment. However, modern building design — particularly for high-rise structures, healthcare facilities, and buildings accommodating persons with disabilities — has prompted renewed interest in lift evacuation as a complement to stair evacuation.

The Technical Report provides a structured decision chart methodology that enables building designers, lift engineers, and fire safety professionals to systematically evaluate whether lift evacuation is appropriate for a specific building, what hazards must be addressed, and what technical solutions are required. The decision chart covers 21 distinct risk scenarios organized into four categories: fire-related hazards, non-fire hazards (explosion, chemical, biological), environmental hazards (flood, storm, earthquake), and lift system hazards (power failure, control system failure, mechanical failure).

2. Technical Solutions and Design Requirements

Annex A of the Technical Report provides detailed technical solutions for each of the 21 identified risk scenarios. For fire-related hazards, the key requirements include: a fire-resistant hoistway enclosure with fire resistance rating of at least 60 minutes, a protected lobby at each lift landing with automatic closure and smoke detection, a backup power supply capable of operating the lift for the full evacuation duration (typically 30–120 minutes depending on building height), and a communication system providing real-time status information to passengers and building management.

For non-fire hazards such as chemical or biological agents, the report addresses the need for hoistway pressurization to prevent contaminant ingress, HEPA filtration of lift car ventilation air, and the provision of emergency decontamination procedures. The report emphasizes that the specific technical solutions must be tailored to the risk profile of the building, which is determined through a structured risk assessment process that considers building location, occupancy type, and the likelihood of specific hazard scenarios.

3. Engineering Design Insights for Lift Evacuation Systems

From an engineering design perspective, implementing lift evacuation requires a holistic approach spanning architectural design, structural engineering, fire protection engineering, and lift system design. One of the most challenging aspects is the coordination between the fire alarm system, the lift control system, and the building management system to ensure correct sequencing of evacuation operations. The lift must be automatically recalled to a designated evacuation floor upon fire alarm activation, with doors opening to allow boarding while preventing access to fire-affected floors.

Another critical design consideration is the water protection of lift installations. Fire sprinkler activation can introduce large volumes of water into the hoistway, potentially causing short circuits, brake failure, and car entrapment. The report recommends that lift evacuation systems include: water drains at the pit bottom with capacity equivalent to the sprinkler system discharge rate, weatherproof enclosures for electrical components located near the pit floor, and a lift car design that prevents water ingress into the passenger compartment during descent through sprinkler-activated floors.

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