Investigation On Emergency Ventilation Strategies To Control The Dispersion Of Indoor Contaminants

As the chemical and biological attack by terrorists occurs frequently in buildingsin recent years, it has become a threat to the public environment throughout the world.Since most of such attacks were indoors, the ventilation system, if properly designed,could help reduce the total loss during the event. Thus, the emergency ventilationcalls more and more attention in the research field. Unlike the commonly usedventilation system for thermal comfort and indoor air quality, emergency ventilationemphasizes on the temporal development and dispersion of the contaminant in alimited period of time after it is released. In addition, many investigations have shownthat, occupants only move in a limited region in the room during evacuation processwhen they know such emergency event occurs. Therefore, the present emergencyventilation study mainly emphasizes on the portion of the space which can influencepeople's safety and health. Based on such concerns, the main work of this research isas follows:1. The whole process of determining ventilation strategy to protect the indoorenvironment against contamination is first proposed, which includes examiningthe room function and the capability of the ventilation system, providing suitableemergency ventilation strategies for different situations by using CFD analysis,identifying the location of source locations when emergency event occurs, andswitching the ventilation style into the optimal one upon necessity.2. Two methods to evaluate the effect of ventilation for the purpose of defendingemergency are investigated. The one based on IACS can evaluate the ventilationstrategy without knowing the intensity and components of the source;the otherone based on the evacuation model and the Haber's Law can reflect theventilation performance in more detailed and logical way, provided the intensityand the component of the source are known.3. An occupant evacuation model based on the idea from fire science is developedand used to calculate the total exposure.4. A method based on zonal model is proposed to identify the location of pollutantsources, and the discrepancy between the predicted location and the actual one isdiscussed.