In an office building where several people carry out their day-to-day activities, it is important to make adequate design for fire safety. A well laid out design helps to reduce the incidence of fire outbreak and fire related injuries. It lowers the panic rate of occupants within an affected building or area.
The following factors should be considered when designing for fire safety in the workplace:
Fire Resistant Construction
Construction materials for any building should be chosen having regard for the safety of the structure and its occupants. The choice for wall and ceiling finishes and also linings for furnishings can significantly affect the spread of fire and its rate of growth, even though they may not be the materials first ignited.
To inhibit the spread of fire within the building, the internal linings should resist the spread of flame over their surfaces, and if ignited, should have a reasonable rate of heat release.
Means of Escape
Safe routes from any point in a building should be provided for persons to escape in case of fire. These include protected lobbies, corridors and escape stairs. Information required to provide adequate means of escape include:
- Number of Occupants – dependent on the intended use of the floor space.
- Density factors (the available floor space per person).
- Widths and Number of Exits – This depends on the occupancy factor. When this is known the number of exits must equate the necessary total width of escape required. Where there are two or more exits, it is assumed that fire may affect one of them, therefore the largest exit should be discounted when calculating the number of exits required.
- Travel distances – the number of exits may be determined by recommended travel distances, i.e. the actual distance to be travelled to the nearest exit. A person should be able in most circumstances to turn their back on a fire and walk to an alternative exit.
If escape is in one direction only, an exit or alternative escape route should be near enough for people to reach before being affected by heat and smoke. It is usually recommended that the angle of divergence should be not less than 45° plus 2.5° for every metre travelled in one direction.
Time of evacuation – This is dependent on Building construction and Occupancy. The generally accepted times are:
- Class ‘A’ construction (complete non-combustible construction) – 3 minutes.
- Class ‘B’ construction (non-combustible walls with combustible floors) – 2.5 minutes.
- Class ‘C’ construction (combustible construction) – 2 minutes.
These times are subject to extension or reduction, depending on the circumstance.
Escape for people with disabilities
Special consideration should be given to people with disabilities. It may be necessary to construct protected refuges adjacent to lifts and stairs for those in wheelchairs and with limited mobility. Blind people need help to find the exits, and deaf people require audible warnings to be duplicated by visual ones. In all cases, controlled escape is vital and assistance should be available.
Lighting and directional signage
Emergency lighting should be provided in the areas necessary for escape purposes in case the artificial lighting fails. It may be a maintained system (continuously illuminated in conjunction with the general lighting) or be non-maintained (only coming into operation on the failure of the general lighting).
Fire signs are also required to indicate the way to exits, and the exits themselves. Signs should be distinguishable against their background and surrounding and also be visible from required distances.
Fire Protection Appliances and Installations
The primary danger associated with fire in its early stages is not the flame but the smoke and noxious gases produced by the fire. They cause most of the casualties and may also obscure the way to the escape route and exits.
Fire Protection Appliances should however be provided. They include:
- Warning Appliances – alarms and detectors for smoke, heat and fire.
- Active extinguishing systems – fire blankets, fire extinguishers, sprinklers and hose reels.
Fire safety management
The management of any work environment has a duty to make sure that the workplace and the people who work there are kept safe from fire and its effects. To this end, the management is expected to have fire safety strategy for the premises following a fire risk assessment. It is also necessary to provide information and train the employees on fire precaution in the workplace and what to do in the event of fire.
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