Evacuation Analysis - RIBA

Management Summary

To meet the UK building fire safety requirements either a prescriptive or performance-based fire analysis approach will need to be performed. In the case of performance-based analysis, also known as Fire Safety Engineering approach, crowd simulation tools can be used to determine the Required Safe Egress Time (RSET) which is compared to the Available Safe Egress Time (ASET). The ASET is often determined using a fire modelling tool. This use case will examine the stages involved in the UK RIBA guidelines to identify current UK fire safety practices and data exchanges performed during the building design phase.

Use Case Definition

An application of evacuation analysis as part of the performance-based design was applied to a multi-story office building.

When it comes to occupants' safety in buildings, prescriptive codes are in place. But for special and more complex buildings such as e.g. stations, airports, high rises, such prescriptive rules are not always applicable. As such, new methods have been developed in order to cope with the requirements. Performance-based approaches compare the Available Safe Egress Time (ASET) against the Required Safe Egress Time (RSET) of a building. In order to determine the RSET of a building, crowd simulations can be applied. These kind of simulations determine evacuation times and possible bottlenecks of building designs. In order to support such simulations, common building information models have to be enhanced by information needed by these simulations.


Aim and scope

The aim is to identify the performance based fire safety analysis workflow related to the evacuation design of a given structure in relation to the UK RIBA stages.

The focus will be on the building design stages, which are stage 2, 3 and 4 of RIBA.


  1. Identify the actors and stages involved in the evacuation design phase.
  2. Identify the workflow for evacuation modelling tools.
  3. Identify data exchange requirements to carry out evacuation analysis using modelling tools.
  4. Identify current IFC support for data exchange and limitations, together with areas for improvement.



  • Approved Document B (AD B) [AD B is a prescriptive document that allows alternative solutions to be implemented for more complex scenarios. These alternative solutions are typically called fire engineering solutions or performance-based solutions.]
  • British Standard (BS) 7974:2001 – Application of Fire Safety Engineering principles to the Design of Buildings, code of practice [The BS 7974 is the main document that provides technical support for the development of fire engineering solutions, including human factors and computational modelling]



Fire Safety Engineering (FSE)

Occupant Movement Analysis (OMA)


  1. This use case is based on UK RIBA stages.
  2. Focused only on the design stage.
  3. Only covers office buildings.

Project Group



The documents reflect the current best practice and do not claim to be complete. They should not to be understood in the sense of a generally valid recommendation or guideline from a legal point of view. The documents are intended to support appointing and appointed parties in the application of the BIM method. The documents must be adapted to the specific project requirements in each case. The examples listed do not claim to be complete. Its information is based on findings from practical experience and is accordingly to be understood as best practice and not universally applicable. Since we are in a phase in which definitions are only emerging, the publisher cannot guarantee the correctness of individual contents.

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  • Document Type : Use Case
  • GUID : CCEB0BA5-0E8F-4CA2-80E5-B6CF856BA003
  • Identifier : OMA-EVAC-RIBA
  • Life Cycle Stage : RIBA - plan of work
  • Revision : V1.0.0.0
  • Project Status : Draft
  • Maturity level : Example
  • Use Case: Draft
  • Processes: Draft
  • ER: Draft
  • Published on: Dec 6, 2021
  • Last change: Jan 14, 2022
  • Publisher: buildingSMART International
  • Author: Abualdenien, Jimmy | Kneidl, Angelika | Lawrence, Peter | Lehtoviita, Timo | Siddiqui, Asim