Transportation and HVAC Systems for Building Emergency Evacuation

Building emergency evacuation has long been recognized as an important problem, since safety is a major concern for building occupants. The paths selected for egress should be pressurized with fresh air through HVAC airflow control. The problem is to minimize the egress time by reconfiguring HVAC units and selecting egress paths for occupants in a building, subject to path capacities and HVAC system limitations. The interdependency of the transportation and HVAC systems and the combinatorial nature of discrete optimization make this a challenging problem. For simplicity, steady-state airflow analysis over each duct is used, and dampers are considered either fully open or fully closed. Our key idea is to make full use of traditional network flow models for egress while considering the fan power capacity as a constraint. The problem is solved by iteratively using a maxflow algorithm while exploiting dominance properties to reduce the search space. An optimized reconfiguration of the HVAC is established, resulting in significant improvements in evacuation time