Fire: Prevention and protection

This week, we're looking at the effects of fire, how the combustion process operates and the principles of fire prevention and protection (T033 Fire Safety). When you take your APC, at competency level 3, you'll be asked to demonstrate you understand the principles by talking through a fire strategy for a sample building you have been involved in.

Competency Level 1

Question Please provide an overview of the consequences of fire within a building and how fire risk can be reduced through preventative and protective fire safety principles.

Answer This is quite a broad question and the candidate should look to break down the response into a number of key areas. The following would be relevant to this question:

• Provide examples of the consequences of fire

• Look at how the type of building and enclosure will determine the impact of fire

• Overview safety principles to minimise risk from fire

The Consequences of Fire

The consequences of fire can be wide ranging and include:

• Loss of life

• Injuries as a result of the fire or evacuation of the building

• Property damage - both cosmetic and structural

• Loss of data and records

• Loss of business

• Reputation damage arising from difficulties in continuing to trade

Building Type Influences on Fire Impact

Three things are required for a fire to start – an ignition point (e.g. faulty electrical equipment), a fuel source (e.g. the actual appliance and material around it) and lastly oxygen (which in most instances we cannot avoid). These three elements make up what is known as the ‘fire triangle’.

In terms of building type, the main influences are on the fuel source and oxygen supply elements of the fire triangle. The design of the building and the materials and appliances that are incorporated into it, will ultimately have an effect to whether a fire could start and consequently spread. There are also features of the building use that affect fuel sources with the simple example being the storage of paper records.

Examples relating to fuel sources would include the materials used in the construction and finishing such as timber, furniture, carpets and the like. Examples relating to oxygen supply include open windows and doors which promote rapid fire spread, lift and ventilation shafts which can act as chimneys and ventilation ducts which can allow the spread of smoke and fire.

The building may also be fitted with both passive and active fire controls. Examples of passive controls would include fire doors, duct fire dampers and electrical fault protection equipment. Candidates should show they understand in greater detail some of these components, for example with fire doors there could be an explanation of how a fire doors are rated and recognised in existing buildings, the role of self closing devices and intumescent strips, etc.

Active controls would include fire detection systems and sprinklers. The candidate could further demonstrate their competence by explaining the difference between heat detection and smoke detection systems, showing an understanding of zoning in a buildings and also how ‘addressable’ alarm systems can be used in more complex buildings.

It is important to be clear that fire prevention must always be considered first before looking at fire protection measures, although this is not to say that fire protection measures should be ignored.

Fire Safety Principles

To reduce the likelihood of a fire occurring and possible loss of life / injuries that may happen as a result, the professional team need to ensure that key fire safety principles are embedded throughout the process of design and specification. In short, the design and use of the building needs to ensure that the 3 elements of the fire triangle (fuel, heat, oxygen) do not come together.

Candidates should demonstrate a basic understanding of Part B Building Regulations and Regulatory Reform (Fire Safety) Order 2005, together with how the two pieces of legislation sit together and the relevant enforcing authorities. Further knowledge of legislation could be demonstrated by explaining how the Regulatory Reform (Fire Safety) Order 2005 superseded the Fire Precautions Act and the options to design in accordance with the prescriptive requirements of Part B or the Building Regulations or a ‘Fire Engineered’ solution.

Candidates should also show their understanding of how building design and layout affects fire safety by covering topics such as the concept of travel distances within a building, horizontal and vertical escape, building compartmentalisation, what is meant by dead-end corridors and ‘inner rooms’ together with how these are treated from a fire safety perspective.

There are also aspects of fire risk reduction that relate to how the design of the building layout is configured. For example a kitchen provides many potential sources of ignition and the layout would ideally locate this room away from others that could provide major sources of fuel, for example archive storage rooms.

Although not specifically the focus of the question here, it would be worth the candidate showing an awareness of fire safety when the building passes into use. This would include maintenance of fire detection and suppression systems, training and organisation of fire wardens, fire risk assessments and personnel evacuation briefings.

Level 2

Question Give a practical example of how a fire can take effect and give examples of the physiological and psychological effects from fire. Provide an overview of the factors that would be taken into account in conducting a fire risk assessment.

Answer A simple example of how a fire could take hold would be an electrical fault in a photo copy machine. The electrical system failure could provide the ignition source (although this risk is mitigated to a large degree normally through the protection provided on electrical circuits and the insulation of parts) and the paper in the machine could provide the fuel supply. The fire would initially feed off the oxygen in the building space in which the copier was housed and may then spread to furniture and other elements of the building fabric. The degree to which the fire then spreads within the building then depends on the compartmentalisation of the space, how that compartmentalisation restricts the air flow to the fire and the fire ratings on the components (fire doors etc) that are providing the containment.

The physiological effects of fire can include:

• Smoke inhalation

• Burns

• Singed hair

• Unconsciousness

• Death

The psychological effects from being involved in a fire incident include:

• Panic

• Fear

• Post Traumatic Distress Disorder

• Behavioural problems

• Low self esteem

Fire Risk Assessment

In undertaking fire risk assessments reference should be made to the Building regulations and Regulatory Reform (Fire Safety) Order 2005. This provides requirements and guidance on the issues that should be taken into account which include:

• Sources of ignition

• Sources of fuel

• Compartmentalisation of the building

• The number of width of escape routes including the concept of discounting one stair for MoE calculations

• The length of escape routes

• Compartmentalisation of escape routes

• Smoke discharge systems

• Emergency lighting of different types including where it is appropriate to use each type

• Smoke extract ventilation

• Escape route signage

• Time it takes to get out of the building

• Fire detections systems and different categories of fire alarm

• Fire suppression systems / devices and the different types of these, for example the use of inert gas suppression in comm’ rooms

Level 3

Question Talk me though a fire strategy for a building which you have been involved in and explain the factors that were taken into account.

Answer The response to the level three question will clearly be specific to the candidate’s particular experience. Through the response the candidate should demonstrate the application of the principles outlined above in developing the fire strategy and explain how that strategy is validated and then used during the design process.

The strategy itself should demonstrate the ways in which the chosen design and specification meet the requirements of the relevant building and fire regulations. It should provide the philosophy around which fire safety and fire protection measures can be further defined as the design process proceeds and sets out the evacuation strategy including any phasing in more complex buildings.