The occupant capacity of an event is the number of persons who can safely be present at the event. You will need to work out the occupant capacity for your event and ensure that this figure is not exceeded. For a ticketed event, the occupant capacity figure should be used to set the maximum amount of tickets that can be sold, for a non-ticketed / free event, alternative measures may need to be found to restrict entry where necessary.

The occupant capacity for an event is the lower of two figures:
The occupant density of the event.
The exit capacity of the event.

The occupant density of the event refers to the amount of persons that can safely fit into the space available. The exit capacity of the event refers to the amount of persons that can safely be evacuated from the site if necessary given the available exits.

The occupant density of an event can be worked out by finding the total available space in meters squared and multiplying by two. The HSE recommendation for available space per person for outdoor events is 0.5 meters squared. This figure is often referred to as the occupant load factor for such Events. Multiplying the total available space (in meters squared) by two will give you the number of people that can safely fit into the space available. To find the total amount of available space you will need to find the total space of the site and subtract all space taken up by structures or other inaccessible areas.

The exit capacity of an event can be worked out using the formula below. You will need to ensure that you have sufficient available exits, using this formula, for the number of public on site to leave safely should a fire occur. Designated Emergency Access Gates do not count as available exits. You should also discount one available exit from the calculation to account for the fact that the Emergency situation occurring may block an exit or otherwise restrict its use. The minimum width of a exit should be 1.05m.

Exit capacity = Number of people divided by Flow rate x escape time

The current recommendation for escape time from outdoor events is between 5 and 10 minutes depending on the level of risk involved. The given flow rates are 73 people per meter per minute for open air seated areas and 109 people per meter per minute otherwise.

For example, to find the exit capacity of an low risk non seated outdoor event site with 5,000 visitors:
Exit capacity = Number of people divided by Flow rate x escape time
Exit capacity = 5000 divided by 109 x 10
Exit capacity = 4.58m
For 5,000 visitors 4.58m available exit width must be available, excluding emergency exits.

The minimum width of a exit should be 1.05m so, in this case, 5 minimum width exits would be required (totalling 5.25m) or 3 minimum width exits (totalling 3.15m) and one larger exit of 1.43m.

A further exit should be provided in case one exit becomes inaccessible due to the emergency occurring. This must be large enough to ensure that whichever of the original exits is taken out, the exit capacity for the event is still met.

The occupant capacity for an event is either the occupant density for the event or the amount of people that can safely leave the event site given the available exits using the exit capacity formula given above. The smaller of these two numbers will be the occupant capacity for the event.


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