Risk and Performance Standards

Performance codes are replacing prescriptive codes in much of the world. As the form of the codes change, the form of standards which support those codes needs to evolve in concert. Thus, performance standards need to be explicit about the purpose(s) served by the standardized systems and to provide quantitative means to assess the degree to which they serve that purpose. Most of the engineering methods evolving to support performance based codes assess risk to life of building occupants relative to the risk to occupants in buildings which comply with the prescriptive code. Such relative risk assessment is cumbersome and unreliable, and should be replaced by absolute risk limits to enjoy all of the efficiencies of performance codes. Financial risk is easy to understand but is inappropriate to codes that exist to protect life. Risk to life is difficult to understand and communicate to the public. These risk analysis methods utilize scenarios as a bridge to experience and the means to quantify likelihoods. In the absence of incident data some systematic methods of identifying scenarios is needed. This paper deals with each of these issues in an attempt to stimulate research needed to find the answers. 1. BACKGROUND The worldwide migration to performance-based fire and building codes has placed new demands on the engineering profession. One of the most challenging is for meaningful ways of assessing the degree to which specific designs meet the requirements which society places on its constructed facilities. With regard to fire safety, it can be argued that society expects the risk of death or injury from fire to be held to some acceptable level that varies with occupancy. For example in residential occupancies, people are generally willing to accept higher risks in their own homes as compared to hotels. The general risk literature suggests that society expects the risk of multiple deaths or injuries per incident to be decreased, roughly in inverse proportion to the numbers (i.e., the risk of 10 deaths in an incident should be 1/10 that of a single fatality). What is not clear is how to communicate risk implications to policy makers and the public, and how to arrive at risk targets that society considers acceptable. The fact that every draft performance evaluation system is risk based makes it clear that risk is the metric of choice for the performance-based safety regulations of the future. This fact raises certain issues which need to be addressed early so that this beneficial process is not unnecessarily delayed. Some such issues include: 1. The regulatory system is made up of codes and standards -the former dictate what is required and the latter how to implement something that is required or provided voluntarily. When adopted, both have the force of law, but codes establish the fundamental requirements and standards expand on the details. In the debate over