A042 Egress time

Risk analysis of escape time from buildings

Brief:

Purpose – To model the evacuation time from buildings in the event of emergencies based on occupant load, looking specifically at the exit width as a design parameter.

Design/methodology/approach – In this study, transient occupant loads from a simulation model based on a recent study of 34 offices in Hong Kong were used to evaluate the probable risk to evacuees in the case of an emergency evacuation. For this analysis the “door carrying capacity” approach was used, together with probability profiles for the occupant loads at certain exit flow rates. This paper investigates the occupant load profiles as well as the yearly and daily occupant load variations of some typical offices in Hong Kong and examines the fire safety implications of the office building designs from the perspective of the risk to evacuees.

Findings – The results show that the building occupant load, occupant-load ratio, total exit width and specific flow rate at the exit significantly affect the risk to evacuees.

Research limitations/implications – The model parameters are not exhaustive and are determined from surveys in Hong Kong.

Practical implications – A useful source of reference in conducting risk assessment for safe egress design of office buildings for those involved in building design, operation and management.

Originality/value – This paper, taking account of exit design, occupant load and its variations using the door carrying capacity approach, presents a simple method to determine the probable risk to evacuees in offices.

Further information:

Wong LT, Fong NK, 2005. Risk analysis of escape time from buildings, Facilities 23(11/12) 487-495.