Performance-based Approach to Fire Safety Design (By Fire Division)

In Hong Kong, fire safety design in a building can be demonstrated as compliance with the statutory regulations by either following the prescriptive guidance from codes of practices or adopting alternative solution with the support of engineering justifications. When a building is found to be difficult to fully comply with the prescriptive requirements in fire safety design, the fire safety performance of the alternative solution is required to be assessed to demonstrate that an equivalent fire safety level as prescriptive design or an acceptable fire safety level can be achieved. This is Performance-based Approach which is generally recognized as Fire Engineering Approach (FEA) for fire safety design of building.

What is Fire Engineering?

Developing fire safety design using FEA is a design process which, by consideration of the hazards and risks involved and the precautions that are possible, achieves a balanced and acceptable level of fire safety. This is application of scientific and engineering principles and common sense to the protection of people, property and the environment from fire. The process will involve:

  • Identifying hazards and fire scenarios
  • Setting acceptable criteria of fire safety
  • Defining alternatives and/or mitigation
  • Carrying out qualitative and/or quantitative analyses
  • Reviewing and evaluating of performance 

Fire Engineering applies the first principles of fire science to derive the fire safety design. Credible fire scenarios that potentially threaten the life safety in a building will be analyzed and compared to the human protection acceptance criteria. For example, the design should ensure the smoke layer can be maintained at high level (at least 2m above floor level) so that evacuees will not be affected by smoke during evacuation; appropriate fire suppression system should be provided to extinguish or control the fire to avoid fire spread. Other than objective proof by scientific analyses, effective means for fire-fighting intervention and fire safety management for maintaining and ensuring proper operation of fire safety systems during emergency are part of the design considerations to allow an integrated fire safety strategy for optimizing the fire safety level of a building. 

Application of Fire Engineering Approach in Hong Kong 

Hong Kong is one of the few places in East Asia adopting FEA in the design of fire safety in buildings. The first few buildings in Hong Kong that adopting FEA include the Hong Kong International Airport, the HSBC Headquarter in Central and the Festival Walk Shopping Mall in Kowloon Tong. These are iconic buildings designed in the period between the late 80s and mid 90s. At the same time, the development of the Mass Transit Rail (MTR) system provided a significant boost to the popularity of FEA in fire safety design. As it is recognized that codes and regulations for typical buildings are not suitable for MTR stations and rail tunnels. FEA offers tailored solutions to address the specific hazards and risks of the MTR system.

The use of FEA in the fire safety design of buildings continued to grow and become popular in the early 2000s. FEA was adopted to increase flexibility in design, to support architectural aspiration or as part of value engineering while maintaining the safety level of the developments. FEA has continuously been applied in many iconic buildings and developments in Hong Kong including Innovation Tower of The Hong Kong Polytechnic University, the Central Police Station Compound (“Tai Kwun”), the Xiqu Centre at the West Kowloon Cultural District, and the future Kai Tak Sports Park at the Kai Tak area. 

The Role of Fire Engineer

The main responsibility of a Fire Engineer in a project is to ‘look after’ the fire safety aspect of the design, usually at the strategic level. The Fire Engineer will set out the Fire Safety Strategy of a building, such as the use classification, the hazard classification, the evacuation strategy, the fire resistance rating to the structure, the active and passive protection systems to be provided, etc. The Strategy should be a live document which describes the operation of a building in the event of fire. Any significant changes to such operation or building features that affect the fire safety should be reviewed and reflected on the Strategy. 

The activities carried out by a Fire Engineer in a project differ from one project to another. In some projects, the Fire Engineer will only provide code consultancy, which is to assist the design team in understanding, interpreting and implementing the requirements in the codes. In other cases, the Fire Engineer will be involved in dealing with design issues that are not compliant with the prescriptive requirements in the codes. In Hong Kong, the latter is often the reason for a Fire Engineer to be involved in a project. It is also possible for a Fire Engineer to provide both code consultancy and carry out FEA for a project. This is more typical for large scale projects or projects involving unique structures or use.  

The role of a Fire Engineer is not only limited to the design stage. Recently, Fire Engineers have been requested to provide their expertise during the construction stage of a project or even after the building has been occupied for some time. The activities of a Fire Engineer during those stages of a project include carrying out site inspection of the fire safety provisions, risk assessment or due diligence of a building in use. 

Looking ahead

There are several challenges in adopting FEA for building designs in Hong Kong. One of the reasons is low popularity of FEA which not many people understand what it is and be willing to work on this industry. With the increasing demand of dealing with different fire safety issues throughout the life cycle of a building, FEA should be further promoted and supported by all the stakeholders including the Government in Hong Kong. 

Written by Ir Anny IP from the Fire Division of the HKIE

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