Consultants often ignore the building roof’s geometry and the required substitute rectangular volume used in smoke-fill formulae. Therefore the qualitative review under rational design includes an architectural review, fire-safety objectives, fire hazards and risks, trial fire-safety designs and worst-case fire scenarios for analysis.
All buildings in South Africa must comply with the requirements of the National Building Regulations and Building Standards Act, 1977 (Act 103 of 1977), Fire Protection, as set out in SANS 10400 Part T: 2011. Any digression from the prescriptive requirements requires a rational design.
This must be completed in accordance with the fire-engineering methodology framework requirements of BS 7974. The Application of Fire-Safety Engineering Principles to the Design of Buildings, supported by the published documents, forms an integral part of the BS 7974 framework.
3 critical steps to follow:
Step 1: Rational design
A rational design is the performance-based design of fire safety and prevention mechanisms and strategies in a building in order to provide the same or better fire-safety levels of the National Building Regulations, where the prescriptive requirements cannot be applied. This process is not elective, in as much as that only certain parts of the framework may be used, or that the results of the process are subjective or optional.
A rational design commences with a fire-risk consultant visiting the premises or reviewing a set of new building plans, to undertake a comprehensive evaluation of all areas of the property to inspect all areas of fire safety and risk in detail, ASP Fire chief executive officer, Michael van Niekerk, explains.
“Rational design considers the behaviour of a building during a fire, meaning the structure must be designed accordingly, thereby minimising any potentially devastating impact. Engaging a fire engineer at the earliest possible stage of the design can avoid costly fire-protection systems by designing from the start with fire in mind,” he says.
Step 2: Quantitative analysis
Following the qualitative review, the next step is quantitative analysis in accordance with BS 7974. Here the focus is on the development of fire within the enclosure of origin, the spread of smoke, structural response and fire spread beyond the enclosure of origin, detection of fire and activation of fire-protection systems, fire-services intervention and evacuation of occupants.
Step 3: Criteria assessment
Assessment against criteria is the final step, where the fire-safety designs developed during the engineering analysis are assessed to ensure that the objectives established at the beginning of the process are, in fact, met.
What happens next?
Upon completion of the fire-risk assessment and drafting the rational design report, ASP Fire provides the client with practical actions to implement. The report comprises a detailed and documented objective fire-risk assessment, as well as fire-engineering calculations and analysis where required, covering all aspects of fire risk and safety.
Why is this process necessary?
“This guides the client in protecting its business, employees and customers by providing prioritised recommendations for action, in order to rectify problem areas and strengthen existing fire-safety procedures. This also ensures that the client complies with fire-safety regulations for the protection of life, property and the environment,” Van Niekerk highlights.
Need to know:
ASP Fire also works closely with insurance brokers and underwriters to address a client’s fire risk based on the outcomes of the fire-safety risk assessment report. This assists in preventing damage to property and products, loss of life, financial loss, consequential loss of profit, loss of productivity and insurance repercussions.
Acknowledgement and thanks go to ASP Fire for the information contained in this article.
A rational design is the performance-based design of fire safety in a building.
All buildings in South Africa must comply with the National Building Regulations and Building Standards Act, 1977.
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