Fire Safety Science Digital Archive

Natural or mechanical smoke exhaust systems are supported to install in tall buildings for removing hot smoke from fire in Taiwan’s building code. Normally, the mechanical smoke exhaust volumes are designed according to floor area or given an assigned value of 120 m³/min. An opening area of 2 m² or 3 m² is commonly used for natural smoke exhaust vent in Taiwan’s building code. However, the wind effects on tall buildings are not included in Taiwan’s building code or fire safety regulations. The smoke exhaust systems are strongly influenced by wind effects, especially, for tall buildings. Therefore, an experimental study using a wind tunnel was conducted to investigate the fire pressure and wind induced pressure around tall buildings. Improvements of the design of the smoke exhaust systems of tall buildings were submitted according to the test results. A height-to-wide ratio 4:1 model building was adapted to measure wind pressure in a wind tunnel with a 4 m x 2.6 m cross section area. Three important smoke exhaust system design parameters, building height, smoke temperature and wind angles are adopted to analyze the wind tunnel test results. The study will present useful and practical design limitations of natural/mechanical smoke exhaust system for different building heights.