BackgroundFire safety and security (with or without CBR building protection) are often a significant part of any major construction effort. However, a disconnect often exists between life safety requirements (get every occupant out of the building safely) and security (prevent unauthorized access). While there are prescriptive code requirements that generally address these situations, there is little consideration for new technologies that have yet to be written into the code, but that may provide a superior solution.
The code development and adoption process, which defines the construction and design of the vast majority of buildings within the United States, inherently has difficulty reacting to changing conditions. An example is the rapidly emerging threat posed from CBR attack by terrorists. The growing concern over chemical and biological terrorist attacks has exposed the discipline of CBR building protection to a wider base of projects.
While dealing with terrorist threats and attacks is clearly not within the scope of traditional building code and life safety documents, many buildings may be susceptible (as direct targets or by proximity to direct targets) and more are being designed, thus this subject needs to be addressed. Unfortunately, the building and life safety codes have no means for dealing with the impact of these types of systems; therefore implementation of effective security and CBR measures can be frustrating and self-defeating.
Fortunately, the advent of performance-based design has created more opportunities for fire protection, security, and CBR building protection to be developed in coordination with, not in conflict with, each other. As a direct result of this convergence, the tools and analyses used for performance-based design are being applied to CBR building protection to create a more streamlined and integrated approach.
What is Performance-Based Design?Performance-based design for the fire protection engineer consists of an engineering process that establishes, documents, and evaluates design and protection options based upon the inherent features of a building or site.
This process is not solely applied to fire protection engineering; it has been used by other building code-mandated disciplines (such as structural engineering) for many years. The primary difference between these disciplines and security is that the building and life safety codes, for the most part, do not regulate security.
Therefore, the field has been performance-based from the start. Implementation of security systems and procedures has been primarily market-driven and has increased as public concern over security has grown.
Performance-Based from the BeginningThe release of a CBR threat agent or toxic industrial material (TIM), such as chlorine, inside or outside of a building could have a serious impact on the building occupants and the equipment within the facility. Buildings are attractive and vulnerable targets to CBR attack for several reasons.
First, containment of CBR agents and TIMs within a confined space allows the threat agent concentrations to remain at high levels for extended periods of time. Second, threat agents are effectively transported throughout a building by the mechanical system. Buildings are designed to provide air exchange via mechanical ventilation and natural infiltration in order to remove carbon dioxide, odor, and heat. In the case of a CBR threat release, these air movement strategies could serve to increase exposures and complicate the decontamination problem.
Third, population densities are high in buildings. During the day or night, people spend the majority of their time inside buildings thereby making the buildings logical targets.
ConclusionThe advent of performance-based fire protection and life safety design provides an opportunity to introduce significant flexibility, practicality, and cost effectiveness to a project when used judiciously.
However, an opportunity is missed if other performance-based disciplines such as security and CBR protection are not integrated into the entire master plan where appropriate.
Considering the complete integration of all fire protection, life safety, security, and CBR protection systems (as necessary) when developing a performance-based design approach would contribute significantly the overall project's success. Otherwise, the maximum potential benefits of a true performance-based design may not be realized. ES