Standard fire safety design guides (such as Approved Document B or NFPA 101 or the National Fire Safey Code of Nigeria) can be overly restrictive on the design of buildings, especially for innovative or unusual building designs.
Fire Safety Engineering offers an alternative approach that focuses on ensuring that the design is safe from fire, rather than just ensuring that it complies with a particular design document.
For example, if an assembly hall has an occupancy of up to 1000 people, Approved Document would state that a total exit width of 5m should be provided (with the largest exit discounted). However, there is no flexibility on that, and if it is not possible to provide 5m of exit width, there is a problem.
Fire safety engineering offers an alternative approach. For example, introducing smoke extraction could delay the rate that the smoke builds up which would allow a longer evacuation without compromising safety. Combining smoke modelling with evacuation analysis could ensure that the hall can be evacuated safely, even with reduced evacuation width.
This is only one example of the use of fire safety engineering. Other fire engineering techniques can also be extremely beneficial, such as radiation analysis, structural fire engineering, smoke modelling and evacuation modelling.
Structural Fire Engineering
In most types of buildings it is necessary to ensure that the structure of the building will remain in place for a reasonable period during a fire. That is to protect the people who are evacuating the building as well as to reduce the risk to any firefighter who may be dealing with the fire.
Structural fire engineering is a technique where the actual fire severity can be predicted for each location within the building, and calculations carried out of the impact of that fire on each element of structure. This can often result in very significant reductions in the amount of fire protection that is required for the structure, and major cost savings.
Some types of structure, such as reinforced concrete, inherently achieve a reasonable resistance to fire (although for longer fire durations, increases in reinforcement cover may be required). However, others, such as structural steel, often need to be protected by insulation to prevent the steel heating to the point where it collapses.
That insulation can be relatively expensive and can affect the physical appearance of the structure, so it is important to ensure that the insulation is not over-specified.
Conventionally, in most types of buildings, the amount of fire protection that is required is based on reference to a standard guidance document that states a specific fire resistance period based on the height and type of building. For example, Approved Document would recommend that the structure supporting a 10m high office building should achieve 60 minutes fire resistance. The fire resistance period refers to a specific duration within a standard fire test furnace and has no direct relationship to how long the structure would last in a genuine fire (this is a common misconception in the construction industry).
This approach is simple, but often results in major over-specification because it treats all structure in the same way irrespective of the fire risk on each element. For example, in some situations structure may be located in very low fire risk locations such as external to the building or in an atrium.
Additionally, detailed predictions of actual fire severity often result in much lower fire severities that those required by Approved Document.
Fire Safety Management
Fire safety management is one of the most important aspects of fire safety in buildings. In order to carry that out correctly, it is important to ensure that there is a fire safety management plan for the building.
This would include issues such as:
- Evacuation procedures and responsibilities for all staff;
- Maintenance and testing requirements for fire safety equipment;
- Management of contractors who may be working in the premises;
- Procedures to follow in the event of any alterations to the building;
- Methods of minimising false alarms;
- Responsibilities for carrying out fire risk assessments; and
- Specific procedures for special events.
Fire Safety Plans
Where a building is of any size or complexity it is advisable to have a set of fire safety plans available. In particular, these are typically needed as part of the handover pack of information needed under Building Regulations and the National Fire Safety Code as detailed in it.
These fire safety plans will document the physical fire safety arrangements within the building, including escape routes, fire service access routes, fire rated walls and the
locations of fire safety equipment such as extinguishers.
The plans can be displayed to help occupants identify escape routes (such as in hotels) and can be used to help staff manage and maintain the building. In particular, specifying which walls need to be fire rated will help ensure that the integrity of those walls is maintained (contractors can be given the plans so that they know to provide fire-stopping in any holes that they may create in those walls).
Fire Safety Audits
Fire safety audits can be required for a number of reasons.
In certain parts of the world, it is a legal requirement for a submission to the relevant fire authorities to include a fire safety audit of compliance against relevant design standards.
In other situations, a client may require an audit of their
building against certain fire standards.
Finally, always look for professional when dealing with fire related issues. Always insist on Fire Safety Design for your buildings. Only fire safety management consultant can do it better.
Remember, fire kills but you can prevent.
Always Think Safety and Practice Safety.
ENGR. AGBILI MARTIN O. (AGILITY)
o/c Fire Prevention/Training/Sensitization
Anambra State Fire Service