Egress, Evacuation and Smoke Modelling
We carry out performance based egress and smoke modelling with Pathfinder and FDS
Egress, Evacuation and Smoke
Modelling
Prescriptive egress rules covering travel distances, exit widths and occupancy factors encode the assumption of a conventional building. For atria, large or complex plants and for phased or refuge based strategies they can be either unsafe or needlessly costly. Performance based egress modelling replaces that assumption with proof, demonstrating that the available safe egress time exceeds the required safe egress time under credible fire scenarios with a margin to spare. We model occupant movement with agent based simulation in Pathfinder to capture crowding, route choice and counterflow, and we couple it with the Fire Dynamics Simulator for smoke spread and tenability against the ISO 13571 life threat criteria and the ISO and TR 16738 timed egress framework. The result is a defensible life safety case that gives you quantified margins between available and required egress time, the bottlenecks we identified and the design or management changes needed to close them.
How the study is executed
A structured, facilitated process that runs from scope definition through close out and produces defensible, actionable outputs.
Calculate occupant load per NFPA 101 / IBC, occupant load factor per occupancy type (assembly 7 sq ft/person, business 100, industrial 100, storage 300), calculate required egress capacity per width (0.2 in/person stairway, 0.15 in/person level).
Verify travel distance per NFPA 101 / IBC, typical 150 to 300 ft maximum depending on occupancy and sprinkler protection, design corridor width (44 inch minimum), dead end length (20 ft typical), common path (75 to 100 ft typical).
Design stair / exit per NFPA 101 / IBC, stair width (44 inch minimum, calculated for capacity), tread / riser dimensions (11 in / 7 in typical), guardrail height (42 in), nosing, illumination (1 fc minimum), specify enclosure rating (1 to 2 hour).
Conduct evacuation modelling per Pathfinder / EVACNET / building thunder, agent based simulation with pre movement time, walking speed, queueing at choke points, benchmark RSET (Required Safe Egress Time) vs ASET (Available Safe Egress Time).
Design for special populations per ADA / IBC Chapter 11, accessible route, area of refuge for mobility impaired, exit signage with tactile / audible features, evacuation chair / lift programme, align with NFPA 101 special purpose requirements.
Design wayfinding per ISO 7010 / NFPA 170 / EN ISO 7010, pictogram signage, photoluminescent path marking per EN ISO 16069, illuminated exit signs per NFPA 101 7.10, design PA / voice evacuation per NFPA 72 / EN 54 16.
What the study covers in full
Outcomes of Egress, Evacuation and Smoke Modelling
- We validate safe egress under credible fires
- We identify bottlenecks and dead ends
- We strengthen emergency lighting and signage
- We support realistic drill design
- We align the design with NFPA 101 and IBC egress
- We document the performance based justification
- We support BS 9999 fire engineering
- We produce work that stands up to AHJ inspection
- We make evacuation drills more realistic
- We improve emergency lighting design
- We support occupant training
- We strengthen your fire warden programmes
- We avoid the over design that prescriptive code forces
- We support flexible architectural design
- We reduce costly retrofits
- We optimise your evacuation infrastructure
Codes & standards we work to
Triggers that signal the need
Where Egress, Evacuation and Smoke Modelling applies
Office towers and mixed use developments.
Process units, control rooms and warehouses.
Mission critical environments with raised floors.
Hospitals, labs and multi occupancy facilities.
Airports, metro stations and terminals.
Offshore and onshore process facilities.
Tangible deliverables
- Egress and smoke modelling report
- Evaluation of available against required safe egress time
- Tenability analysis
- Bottleneck and improvement register
- Performance based justification
- Drill design recommendations
Ready to start your project?
Speak with our team to scope an engagement tailored to your facility, regulatory context, and lifecycle stage.