Does anyone know of any standard or guide to calculate the evacuation time? and if there are reference times, to compare into ours evacuation drills.
Sounds like a simple question. However, we may need more information.
What occupancy group are we talking about here and why are you judging the evacuation capabilities of the occupants?
Hi Milton, is an assembly occupancy, and my intention in not judge the evacuation capabilities of the occupants.
For example if in my evacuation drills the time of evacuation of 80 people is 15 minutes. I would like to know if this time is reasonable or if I can compare to a theoretical time, in that case I would know if I can improve the evacuation time.
I believe there are some figures NFPA uses as the baseline in 101 that help determine the number and sizes of the means of egress. Of course there are many uncontrollable factors, including the fact that we're talking about humans, thus at times it's like herding cats. That said, I'll see if I can find the numbers if I have a chance later this morning, or someone else may beat me to it?
I'd think your example of 80 persons in 15 minutes is a very poor evacuation time for an assembly building. We get hundreds kids out of the schools in under 3 minutes. Granted, their well trained and disciplined compared to us know it all adults... Most assembly buildings should have good means of egress and alarms and the occupants should normally be awake and alert, so getting them to react quickly is the only challenge. Too often they don't take alarms seriously.
I agree the evacuation time appears way too long.
Available Safe Egress Time (ASET) is mathematical model for estimating the time available for safe egress from a fire. You can find several computer programs on the internet. For example: https://www.gpo.gov/fdsys/pkg/GOVPUB-C13-157b48b12ec8344d4fb1a07170742441/content-detail.html
It would be interesting to see if there is more recent data or methods of analysis, as that guidance looks like it was circa 1982. The Fire Service and NIST has undertaken numerous studies of the past few years that reveal the time to flashover is much reduced in today's structures due in large part to the move from natural products to petroleum based products in nearly every furnishing.
As I noted earlier, it was described to our inspector class that NFPA uses/used data to help come up with or legitimize the egress component factors given in NFPA 101-18.104.22.168 These used in conjunction with the minimum numbers of means of egress for a given occupant load should allow adequate time for everyone to egress. I think it may be very difficult to determine a specific time for overall evacuation in an existing building without using some sort of predictive fire modelling that can account for a host of factors.
One could maybe measure the time it takes to follow the egress path from the most remote location in the building to the outside and figure that should be close to the maximum evacuation time in a place where the numbers do not indicate funneling at the egress points? Having people know the expectation is to hear an alarm an immediately begin exiting is part of the battle. Armed with a number, you can use it to set an evacuation drill expectation? Though it's likely you don't have the ability to "school" most occupants in an assembly occupancy, unless it's full of just employees?
Just two 36" egress doors should be able to safely egress 180 persons (using the 22.214.171.124 chart), so an 80 occupant assembly occupancy shouldn't have much issue with egress choke points if all egress paths and exiting is proper?
Of course if you want an actual verifiable answer you may need a FPE.
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