Simulation-based prediction of available safe egress time in care home fires

Abstract

Fire safety in care homes is critical due to the vulnerable condition of elderly residents and because smoke can spread rapidly across the building. The traditional fire safety measures are inadequate for the vulnerable population group, which calls for a specific assessment of fire dynamics and its relationship with evacuation feasibility. This study evaluates the Available Safe Egress Time (ASET) in an elderly care home facility using the Fire Dynamics Simulator (FDS). An IFC model of the building is used, and four fire scenarios – laundry room, kitchen, sauna, and occupant room – are defined using experimental heat release rate curves. Tenability is assessed using visibility and Fractional Effective Dose (FED) criteria. A parametric study based on occupant room fire scenario and a simplified corridor model examines the effect of the corridor length on time required by staff members to evacuate the occupants. A sensitivity analysis is conducted for the toxic species yield using the laundry room fire scenario.

The ASET/RSET analysis is based on both the full-scale, IFC-based simulations and a parametric study. The former shows that evacuation time exceeds ASET even when increasing staff members from one to two. The latter concludes that use of evacuation chair allows evacuation of up to five occupants before FED incapacitation, while evacuation mattress permits none. In both scenarios, visibility reaches its tenability limit before the staff can initiate evacuation. The results indicate insufficient time for evacuation to a safe zone in almost any fire scenario. Visibility deteriorates almost twice as early as FED, causing irritation, restricting the movement and reducing the available evacuation window. Untenable conditions arise between three and twelve minutes in corridors adjacent to fire source.

The study involves uncertainties due to assumptions such as self-closing doors remaining open even after the smoke detection, excluding role of sprinklers in suppression and ventilation limitations. The future studies should explore more efficient methods for BIM-FDS integration, conducting more detailed comparisons between true and surrogate toxic yields, and studying the effect of HVAC systems on the fire and smoke spread within the building.