Fire life and health safety investigation of an innovative ventilation system in underground parking facilities / Kong Kok Haw

Kong , Kok Haw (2019) Fire life and health safety investigation of an innovative ventilation system in underground parking facilities / Kong Kok Haw. PhD thesis, University of Malaya.

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Abstract

City urbanisation induces many large mixed development projects. The increase of population and wealth increases the vehicles ownership. Storing and managing vehicles in underground space is one of the solutions. Enclosed underground parking facilities require more stringent fire life and health safety requirements compared to aboveground space. The requirements are stated in the Malaysia Uniform Building By-Law (UBBL) 1984. Some UBBL passive requirements are difficult to comply for large development. The ventilation requirement for fire life and health safety are often combined into one hybrid system, which is the dual-speed uni-directional ducted ventilation system. This hybrid system delivers air flowrate of minimum ten air-change-per-hour during fire mode to maintain an acceptable fire life safety and six air-change-per-hour during normal mode to maintain an acceptable health safety level. Continuously running the ventilation fans consumes high energy during normal mode. Carbon monoxide (CO) sensors are commonly used in controlling the fans. However, placing CO sensors at particular locations may not reflect the CO condition throughout the entire parking space. This thesis introduces the innovative semi-ducted reversible variable flow ventilation system and static balance duct design method. The passive fire compartments are enlarged, which deviates from UBBL passive requirements. During fire mode, the innovative system extracts the smoke based on pre-determined fire zonings. In this reversible scheme, the fans located in the fire zone operate as extraction and the fans in the adjacent zones operate as make-up air to facilitate the extraction. The information collected from vehicle parking guidance system is able to determine the number of vehicles in a parking facility. The ventilation rate can be varied based on the percentage of active vehicles. From these studies, it was shown that two air-change-per-hour is sufficient for five percent and six air-change-per-hour is required for forty percent of active vehicles. The static balance duct design method uniformizes the air flow for variable-air-volume system. Further studies were carried out based on the human behaviour dependent and reversible zonal control. Humans tend to look for the parking bay nearest to the access point. When more vehicles are detected near to the access point, the fans in that zone will be first operated. When vehicles spread to adjacent zones, the fans in adjacent zones will be started and the fans in the access point zone will be switched off. All fans are designed to reversible and in-paired of zones to create cross ventilation. The fans at zone with higher occupancy will be operated as exhaust and the paired zone becomes supply. This method can effectively remove the hot and contaminated air in a shorter time. The semi-ducted system possesses less ductwork, which reduces fan static pressure and further enhances the energy savings. Simulation results show that this innovative ventilation system is able to enlarge fire compartments by four times with acceptable fire life safety requirements for first application. Second application showed that this innovative ventilation system is able to achieve 94% energy savings in a rectangular underground parking facility while fire life and health safety are achievable.

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