Formulating Acceptable Levels of Fire Risk

Abstract

Building codes and standards traditionally have set levels of performance based on the experienced judgment of the code writer. Occasionally, a certain level of safety is envisioned, but the objective tends to be expressed in imprecise terms, such as the “minimum” or “reasonable” level of safety. There is a need to set goals for fire safety in terms which can be measured so that they can be specified in building codes and standards. With such quantification, systematic fire safety analyses will be more meaningful. A probabilistic approach can be used to set fire safety goals. Sufficient statistics are available today to set realistic goals, and the state of the art in fire safety systems analysis is sufficiently advanced to develop the methodology needed to calculate the failure probabilities for specific events. Such a methodology is described. It assigns probabilities to events associated with fire development in a building and allows these probabilities for a specific set of conditions to be related to the risk being evaluated (loss of life, property damage, business interruption, and so on). Statistics of industry experience help to relate the relative safety levels to the actual loss forecasts. Similar statistical analysis can be used to establish goals for fire safety in building codes, regulations, and standards.