A design assessment system to protect buildings from internal chemical and biological threats
Recent world events involving chemical and biological (CB) attacks within critical infrastructure have highlighted a potential threat to buildings and their occupants. The March 1995 release of sarin gas in a Tokyo subway and the September 2001 mailing of letters containing anthrax spores have demonstrated the viability of using CB agents as weapons on critical infrastructure. These two attacks resulted in 17 deaths with an additional 5000 people being exposed. As a result, protection of buildings from CB threats has become an important design consideration. A design assessment system has been developed to provide stakeholders with the ability to compare multiple building designs for protection against an internal CB release. This assessment system includes modeling and simulation of CB contaminant dispersion, a quantitative method to calculate protection levels, and analyses using econometric statistical and multiple objective optimization models for design selection. This thesis describes the design assessment system phases, and includes computational details for multizone modeling and exposure assessment based on median CB lethal dosages. Multiple design options are considered which include: dilution ventilation, exhaust systems, separate air handling units, high level chemical and particulate filtration, building segmentation, and the use of a CB sensor system. Two-factor random effects and ordered probability (with random effects) statistical models are estimated which identify the design options with higher protection levels. Weighted sum, multiple objective optimization models allow the stakeholder to prioritize design option criteria. The results of the optimization identify the best design solutions based on different weighting combinations of the objective functions. A hospital emergency room with a complex air handling system is used as a case study to illustrate the overall assessment system. ^ The research framework and modeling described in this study will benefit a spectrum of stakeholders which include: owners, designers, planners, occupants, first responders, government, security and financial agencies. The framework provides a systematic and quantitative process to assist with design selection. It can be applied to existing buildings or to evaluate CB protection alternatives in future buildings during the design concept phase. Stakeholders can evaluate building designs based on their criteria and needs. The results can support building planning and future capital investments. Additionally, the methodology can be modified to perform vulnerability assessments of existing buildings, determine ingress and egress routes in the event of a CB attack, and assist with CB resource allocation.^
Dulcy M. Abraham, Purdue University.