# Risk Index Method--A Tool for Building Fire Safety Assessments
## 1 Introduction
### Fire Strategy Evaluation and Fire Risk Assessment  
There is an established understanding that integral to the subject of fire safety, especially fire safety engineering, is the assessment of the risk of fire. Fire risk analysis can range from a simplistic assessment to a much more detailed analysis of how the building, the occupants and the fire itself, interact. [PERSON] et al. [28] introduce a hierarchical holistic model, known as the Integrated Characteristic Interaction Model (ICIM), which considers fire protection viz a viz the relationship with both the building and the persons within the building. They aimed to derive a quantitative method to support a holistic approach to developing a fire strategy and reducing subjectivity in its development. [PERSON] [29] considers how fire risk analysis can be adapted and improved using \"scenario clusters\" to assess building fire hazards. [PERSON] [30] proposes the use of holistic methods to better evaluate fire risk, particularly for a performance-based approach to fire safety engineering. More specifically, [PERSON] et al. [31] proposes that the holistic approach is suitable for determining the fire safety attributes in the design of building facade systems. The common objectives behind such research are to provide more inclusive and consistent methods to apply fire safety to buildings. A holistic methodology to the development of fire strategies, using both qualitative and quantitative approaches, but most of all \"strategic\" techniques, is, therefore, an appropriate direction of travel for the fire industry. British Standard PAS 911 [18] identifies several inputs required for the formulation of a fire strategy. The inputs cover everything from the mandatory framework (national legislation and codes) to the characteristics of the building and its occupancy and even the consideration of practical issues such as logistics and economics. One of these inputs is \"Risk and Hazard Assessment\". The document states that \"a fire risk and hazard assessment will focus the strategy on those aspects of the building that could lead to an actual fire incident\". Furthermore, within the UK, the Regulatory Reform (Fire Safety) Order 2005 uses fire risk assessment as the cornerstone of the legislation. Prior to this, UK legislation was largely prescriptive and did not explicitly consider risk. The use of fire risk assessment to help determine appropriate levels of fire safety design has become increasingly embedded in current fire safety engineering methodologies, especially with the increasing move towards performance-based solutions. To support this, a range of international guides and standards have been produced. These include:  
American standards NFPA 550 [32] and NFPA 551 [33] are guides for the evaluation of fire risk assessments. The scope of these documents states that they are intended to provide assistance in evaluating the appropriateness and execution of a fire risk assessment for a given fire safety problem. The documents are focused on assisting enforcing authorities with jurisdiction over a building in question. They acknowledge that various quantitative, qualitative and semi-quantitative methods may be used to provide a framework and methodology to ensure that various aspects have been properly considered. British Standard PD 7974-7 [13] is a standard that provides guidance for the use of a performance-based approach to the development of fire strategies. The standard explains that probabilistic risk assessment can be used to rank the performance of (fire safety) design alternatives. The standard includes a series of flow charts explaining how the risk approach can be applied. It also introduces a term that has also become increasingly used to define an acceptable level of residual risk: ALARP (as low as reasonably practicable) [34]. This term's idea is that there will always be a level of risk that may be deemed acceptable after reasonable precautions have been taken.