Fire Safety Engineering

According to the UK IFE definition: Fire Engineering is the application of scientific and engineering principles, rules [Codes], and expert judgement, based on an understanding of the phenomena and effects of fire and of the reaction and behaviour of people to fire, to protect people, property and the environment from the destructive effects of fire.

What is a rational design?

According to SANS 10400-T: 2011 Undertaken by a competent person to achieve the same level of fire safety implied in 4.2 to 4.59 ? According to an article which appeared in the “Engineering News”: Rational fire design is the detailed design of fire safety and prevention mechanisms and strategies in a building in order to comply with the National Building Regulations, where prescriptive requirements cannot be met.

The Design Process

At its most superficial level, it is recommended that a fire engineered project should comprise of the following three stages:

1. Qualitative design review (QDR)

2. Quantitative analysis

3. Assessment against criteria

QDR: Review of architectural design

Building characterisation: Layout, geometry, construction

Environmental influences: Climatic conditions affecting structural load, smoke ventilation, external fire spread

Occupant characteristics: occupancy type, population, distribution, AFD

Management of fire safety: Likely extent and nature of building management

QDR: Establish fire safety objectives

Life safety

Occupants can leave relatively safely or risk to occupants is low

Fire-fighters can operate in reasonable safety

Collapse does not endanger people near the building

QDR: Establish fire safety objectives

Loss prevention

Minimise fire damage to:

Structure and fabric of the building

Building contents

On-going business viability

Corporate image

QDR: Establish fire safety objectives

Environmental protection


Effects on adjacent buildings or facilities

Release of hazardous materials into environment

QDR: Identification of fire hazards and consequences

Review to include:

Ignition sources

Combustible contents

Construction materials

Nature and activities of building

Building layout

Any unusual factors

QDR: Establish trial fire safety design

Establish various fire protection strategies

Select cost-effective strategies that satisfy criteria and meet objectives

Actually establishing trial fire safety strategies

Considerations when developing trial designs include: - Control on materials - Automatic suppression and detection - Compartmentation

QDR: Establish trial fire safety design

- Other automatic systems

- Smoke control

- Means of escape

- First aid fire-fighting

- Fire service facilities

- Fire safety management

QDR: Establish fire scenarios for analysis (worst likely case)

Characterisation of fire scenarios for analysis should include the following where relevant:

Fire type

Internal/external ventilation conditions

Performance of each fire safety measure

Type, size and location of ignition sources

Distribution and type of fuel

QDR: Establish fire scenarios for analysis (worst likely case)

Fire load density

Fire suppression

State of doors

Breakage of windows

Building ventilation system

QDR: Establish fire scenarios for analysis

Consider the consequences for each fire scenario

Several fires may need to be modelled e.g.:

A quick developing fire – may be worst for escape but easiest to detect

A hot fire – may be worst in terms of smoke temperature but best in terms of smoke volume production

A fire in the centre of a room may make escape difficult but in a corner will grow quickly

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