National foreword

This British Standard is the UK implementation of ISO 20414:2020.

The UK participation in its preparation was entrusted to Technical Committee FSH/24, Fire safety engineering.

A list of organizations represented on this committee can be obtained on request to its committee manager.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2020.

Foreword

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This document was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 04, Fire safety engineering.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

The objective of fire safety engineering is to assist in the achievement of an acceptable predicted level of fire safety. Part of this work involves the use of calculation methods and models to predict human behaviour in case of a fire. Evacuation analyses are performed to mitigate the adverse effects of a fire on people. The main principles that are necessary for establishing credibility of these evacuation models are verification and validation. This document addresses the procedures for verification and validation of evacuation models. The context of applications addressed in this document is building fires.

Evacuation models are applied to establish the time for an evacuating population to reach a place of safety. Evacuation models are also used to examine evacuation dynamics of different scenarios and to evaluate the effectiveness of procedural solutions.

Evacuation models present different levels of sophistication, ranging from simplified methods (such as capacity analysis or flow calculations) to complex computational agent-based models. Microscopic models represent evacuees in computer models as agents. Each evacuee is represented by an autonomous agent with certain properties, e.g. pre-evacuation time and walking speed. A crowd is built up of a group of agents acting together in a multi-agent-based evacuation model. Agents act according to behavioural rules defined in the model. These rules can represent agent‑to‑agent or agent-to-environment interactions. The macroscopic approach instead represents a crowd at an aggregate level, generally adopting analogies with other physical systems (e.g. hydraulic flows). In addition, in relation to their modelling assumptions in terms of space representation (coarse or fine network approach, continuous approach or hybrid), evacuation models are capable of representing geometries with a different level of accuracy.

Evacuation models operate at three main levels when they produce results, namely 1) Individual Level, 2) Aggregate Level and 3) Scenario level. The individual level deals with the simulation of the actions performed by each agent. The aggregate level concerns the interactions between agents or the interaction between agents and simulated objects which can influence the local conditions. The scenario level relates to the results that summarize the conditions at the end of the simulation, i.e. the final outcome of the model and the layout in which the evacuation takes place.

Potential users of evacuation models and those who are asked to accept the results need to be assured that these models provide sufficiently accurate predictions of human behaviour in fire. To provide this assurance, evacuation models being considered need to be verified for accuracy and validated for capability to reproduce the phenomena. A rigorous verification and validation process are a key element of quality assurance.

There is no fixed requirement of accuracy that is applicable to all possible applications of evacuation models. The accuracy level depends on the purposes for which an evacuation model is to be used. It is not necessary that all evacuation models demonstrate high accuracy in all their components as long as the error, uncertainty and limits of applicability of the models are known. The accuracy of the evacuation model predictions is also highly dependent on the competency of the user, e.g. model configuration, data input selection, results interpretation.

This document focuses on the predictive accuracy of evacuation models. However, other factors such as ease of use, relevance, completeness and status of development play an important role in the assessment of the use of the most appropriate model for a particular application. The assessment and suitability of evacuation models for the simulation of human behaviour in fire in several contexts of applications is supported by the use of a quality-assurance methodology to ensure that the requirements are being fulfilled. Tests and methods for measuring attributes of the relevant model characteristics are outlined in this document.

This document is complementary to ISO 16730‑1, in which the procedures and requirements for verification and validation of calculation methods in fire safety engineering are addressed at a general level. This document should also be used in parallel with the relevant ISO documents in which design scenarios are discussed (ISO 16733‑1 and ISO/TS 29761).

This document is intended to have the following users:

Conceptual model developers (individuals or organizations that perform development activities, including requirements analysis, design and testing of components): These users can use this document to document the usefulness of a particular fire evacuation model for building applications. Part of the model development process includes the identification of precision and limitations of applicability, and independent testing.
NOTE Model developers generally have access to more model components than a user, given their work in the model development phase.
Software model developers (individuals or organizations that maintain computer models, supply computer models, and those who evaluate computer model quality as part of quality assurance and quality control): These users can use this document to document the software features and capabilities and to assure users that an appropriate testing protocol is followed to ensure quality of the application tools by documenting the verification and validation of the model pursuant to this document,
Model users (individuals or organizations that use evacuation models to perform a fire safety analysis): These users can use models verified and validated pursuant to this document to assure themselves that they are using an appropriate model for a particular application and that it provides adequate accuracy.
Developers of performance codes and standards: These users can use this document to specify the verification and validation procedure for evacuation models used in fire safety designs for a given set of applications.
Approving bodies/officials (individuals or organizations that review or approve the use of evacuation models): Theses users can use this document as a basis to ensure that the results submitted show clearly that the evacuation model is used within its applicability limits and has an acceptable level of accuracy.
Educators: These users can use this document to demonstrate the application and acceptability of evacuation models being taught.

General principles are described in ISO 23932‑1, which provides a performance-based methodology for engineers to assess the level of fire safety for new or existing built environments. Fire safety is evaluated through an engineered approach based on the quantification of the behaviour of fire and knowledge of the consequences of such behaviour on life safety, property and the environment. ISO 23932‑1provides the process (necessary steps) and essential elements to design a robust performance‑based fire safety programme.

ISO 23932‑1 is supported by a set of fire safety engineering International Standards on the methods and data required to undertake the steps in a fire safety engineering design as summarized in ISO 23932‑1 and shown in Figure 1 (taken from ISO 23932‑1). This set of International Standards is referred to as the Global fire safety engineering analysis and information system. This global approach and system of standards provides an awareness of the interrelationships between fire evaluations when using the set of fire safety engineering International Standards.

1 Scope

This document describes a protocol for the verification and validation of building fire evacuation models. This document mostly addresses evacuation model components as they are in microscopic (agent-based) models. Nevertheless, it can be adopted (entirely or partially) for macroscopic models if the model is able to represent the components under consideration.

The area of application of the evacuation models discussed in this document includes performance-based design of buildings and the review of the effectiveness of evacuation planning and procedures. The evacuation process is represented with evacuation models in which people's movement and their interaction with the environment make use of human behaviour in fire theories and empirical observations^[⁵^]. The simulation of evacuation is represented using mathematical models and/or agent‑to‑agent and agent-to-environment rules.

The area of application of this document relates to buildings. This document is not intended to cover aspects of transportation systems in motion (e.g. trains, ships) since specific ad-hoc additional tests may be required for addressing the simulation of human behaviour during evacuation in these types of systems^[⁶^].

This document includes a list of components for verification and validation testing as well as a methodology for the analysis and assessment of accuracy associated with evacuation models. The procedure for the analysis of acceptance criteria is also included.

A comprehensive list of components for testing is presented in this document, since the scope of the testing has not been artificially restricted to a set of straightforward applications. Nevertheless, the application of evacuation models as a design tool can be affected by the numbers of variables affecting human behaviour under consideration. A high number of influences can hamper the acceptance of the results obtained given the level of complexity associated with the results. Simpler calculation methods, such as macroscopic models, capacity analyses or flow calculations, are affected to a lower extent by the need to aim at high fidelity modelling. In contrast, more sophisticated calculation methods (i.e. agent-based models) rely more on the ability to demonstrate that the simulation is able to represent different emergent behaviours. For this reason, the components for testing are divided into different categories, enabling the evacuation model tester to test an evacuation model both in relation to the degree of sophistication embedded in the model as well as the specific scope of the model application.

In Annex A, a reporting template is provided to provide guidance to users regarding a format for presenting test results and exemplary application of verification and validation tests are presented in Annex B.

2 Normative references

3 Terms and definitions

4 Documentation

4.1 General

4.2 Technical documentation

4.3 User's manual

5 Verification

5.1 General

5.2 Basic components

5.3 Behavioural components

5.4 Fire-people interaction components

5.5 Building-specific components

6 Validation

6.1 General

6.2 Methods for the analysis of results

6.3 Component validation

6.4 Global validation

7 Review of the theoretical and experimental basis of probabilistic models

8 Quality assurance

9 Quantification of uncertainty

10 Acceptance criteria

Bibliography

BS ISO 20414:2020

Fire safety engineering. Verification and validation protocol for building fire evacuation models

Current, Under Review

Published:

30 Nov 2020