Posted By David J Jones You have identified two of the factors which have a direct impact on evacuation time. There is never a "set" time as you need to consider other factors (the following is not exhaustive) such as multi-storey buildings (from first floor upwards) looking at stairways/stairwells, size and layout of the building, siting of emergency exits in relation to occupancy, nature of occupants (age, mobility, sensory impairment, employees or public) and how you intend to deal with checking everybody has evauated.