Application of the Zone Model FIRST on the Development of Smoke Layer and Evaluation of Smoke Extraction Design for Atria in Hong Kong

Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is determined by its volume. This article reports an evaluation of this regulation using the zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. A survey of the geometri cal configurations of the local atria is made. The general shapes of the atria are classified into three types: 1, 2 and 3, with types 2 and 3 further divided into three sub-types: A, B and C. Smoke filling in those atria is simulated by the model FIRST with the volumes of the atrium space varied from 2500 m3 to 35,000 m3. It is illustrated that specifying only the volume of the atrium space is not good enough to determine whether a smoke extraction system has to be installed. The geometrical configuration is recommended to be included as well. A time constant is defined for the atrium with a certain design fire.