On the evaluation of a `time constant' for studying the smoke-filling processes in atrium spaces

The time constant which has been previously proposed to characterize the smoke-filling time in an atrium space for design purposes is further evaluated in this paper using the CFAST, FAST and CCFM.VENTS zone models developed at the Building and Fire Research Laboratory, NIST, USA. A design fire of thermal power and area related to the volume of the atrium space is proposed in order to evaluate the time constant. Results of the zone-modelling simulation supported the fact that the time required to fill 80% of the atrium space with smoke is related to its time constant. Full-scale experimental results on smoke-filling processes in atria available in the literature are compared. Use of this quantity to specify the smoke-filling time for an atrium space is recommended for design purposes.Department of Building Services Engineerin