Occupant Evacuation Elevators (OEE): How Elevators Became an Evacuation Tool

For most of the twentieth century, elevators were considered unsafe during fires because of three classic failure modes: smoke entering the hoistway and traveling between floors; water from sprinklers entering the elevator pit and shorting electrical equipment; and elevators recalled by automatic operation responding to smoke detection rather than to the occupants who pressed the call button. Posted notices in commercial elevators have for decades read 'In case of fire, use stairs.' The September 11, 2001 World Trade Center attacks brought the question into sharp focus: in tall buildings the time required for the entire population to descend by stair vastly exceeds the time fire spreads, and the disabled population in particular faces nearly insurmountable evacuation challenges. Post-9/11 NIST research recommended elevators specifically designed for occupant evacuation, and the 2009 editions of NFPA 101 and the IBC introduced the occupant evacuation elevator (OEE) framework that has since become standard in new high-rise design.

NFPA 101 Section 7.2.13 and IBC Section 3008 set the design requirements for occupant evacuation elevators. The hoistway must be enclosed in fire-resistance-rated construction matching the building's interior exit stairway requirement (1-hour for buildings less than four stories, 2-hour for four stories or more). The hoistway must be ventilated to prevent smoke buildup. The machine room must be protected from water exposure, with floor drains, sump pumps and water-resistant equipment housings to prevent shorting from sprinkler discharge. The elevator car and shaft must have standby emergency power for at least 2 hours of operation. The elevator lobby on each floor must be enclosed in smoke-resistant construction, ventilated separately from the building, sized to accommodate at least one wheelchair space plus standing occupants waiting for the elevator, and equipped with two-way communication to the fire command center. The elevator must operate under fire service emergency operations Phase I (automatic recall) and Phase II (manual fire fighter operation) per ASME A17.1.

The OEE lobby is the critical safe-area between the building's occupied floors and the elevator hoistway. IBC Section 3008.4 requires the lobby to be separated from the remainder of the floor by smoke-resistant construction with self-closing or automatic-closing smoke doors. The lobby must be ventilated separately so that smoke from the building cannot enter the lobby and travel down the hoistway. The lobby must be sized for the maximum number of occupants expected to use the elevator at any one time, with at least one 30×48 inch wheelchair space and additional area for standing occupants. The lobby must include the two-way communication station required for areas of refuge, with the device connected to the fire command center where occupants can request assistance and confirm their location. The lobby must have illumination on emergency power for at least 90 minutes. Signage in the lobby identifies it as an occupant evacuation elevator lobby and provides instructions for the elevator's use during a fire alarm.

OEE integration with the fire alarm system is more sophisticated than traditional elevator recall. The elevator must remain in service for occupant use during the alarm, not recalled automatically — but the elevator must be capable of being placed under fire service Phase II control when the fire department arrives. The fire alarm system communicates the status of each floor (smoke detected, sprinkler activated, manual pull activated) to the elevator controller and to the fire command center display. The elevator controller manages priority calls: stops at lobby floors with waiting occupants, bypasses floors with active fire conditions, and returns to the level of exit discharge to discharge occupants. Two-way voice communication between each OEE lobby and the fire command center allows occupants to confirm they are waiting and allows the incident commander to direct elevator operation. The system must continue to operate on emergency power throughout the 2-hour minimum operation requirement, even when normal building power is lost.

Occupant evacuation elevators are most valuable in: high-rise buildings (more than 75 ft above lowest fire department vehicle access), where stair descent alone is impractical for the full population; buildings with significant populations of mobility-impaired occupants (large medical office buildings, government buildings, public buildings); buildings with extreme height where stair-only descent would take an hour or more (super-tall residential and office towers); and buildings where the time of day or special events may concentrate occupants beyond what stair capacity can handle quickly. The cost of OEE design — separate ventilation, water protection, standby power, lobby separation, two-way communication, additional fire alarm logic — is significant but often justified by the operational and life-safety benefits. Many modern high-rise designs include OEEs as part of a layered evacuation strategy: occupants choose stairs or elevators based on their location, ability and the location of the fire.

Operational procedures during a real OEE evacuation follow the building's Emergency Action Plan and the integrated fire alarm sequence. On initial fire alarm activation, elevators are not immediately recalled — they remain in service for occupant evacuation. The fire alarm system displays floor-by-floor status on the elevator controller, and the elevator skips floors with active fire conditions. Occupants who arrive at the OEE lobby and find the elevator unavailable can use the two-way communication to confirm their need for evacuation and either remain in the protected lobby (which is also an area of refuge) or proceed to the stair if able. When the fire department arrives, the incident commander may take Phase II manual control of the OEE to use it for firefighter access and to evacuate occupants who cannot use stairs. Staff training, drills and posted plans must all reflect the OEE operational sequence so occupants and responders understand the system.

Posted evacuation plans in buildings with OEEs should clearly differentiate occupant evacuation elevators from regular elevators. The OEE should be marked with the standard elevator symbol plus a specific OEE label and the international symbol of accessibility. The OEE lobby should be drawn as a separate enclosed area (with smoke-resistant boundary lines), labeled as an Area of Refuge / OEE Lobby, and shown with the two-way communication station marked. A note on the plan should describe the elevator's operational sequence — for example, 'This elevator is rated for occupant evacuation use during a fire alarm. Proceed to the lobby, use the call button or two-way communication, and follow staff direction.' Regular elevators must continue to display the 'Do not use elevator in case of fire — use stairs' notice. EvacPlan Generator (www.evacplangenerator.com) supports differentiated elevator symbols, separately drawn lobby boundaries, and text annotations that describe operational expectations — letting facility managers post plans that accurately reflect the increasingly common dual-elevator-strategy in modern high-rise buildings.