In order to properly assess the risk to building occupants during a fire, it helps to have an appreciation of the risks that would be posed as the fire develops. Most of us are familiar with a fire outdoors, such as a campfire, from which one can retreat as it grows. If the wind happens to blow towards you, one simply moves away from the fire to avoid the heat or smoke. Fires in enclosed spaces, such as buildings, behave differently to fires in the open air. The smoke rising from the fire gets trapped by the ceiling and then spreads in all directions to form an ever-deepening layer over the entire room or enclosed space. The smoke will pass through any holes or gaps in the walls, ceiling or floor and into other parts of the building. The heat from the fire will be trapped in the area of the fire, greatly increasing the temperature. There is an added danger to building occupants due to the toxic gases present in the smoke produced by a fire. Smoke contains airborne chemicals which quickly accumulate inside a building. Therefore, it is essential that several means of escape and adequate fire precautions have been established to ensure that occupants can move to a place of safety before the fire and its toxic components trap them in the building. One safety feature of buildings is a smoke control system which can keep escape routes clear of smoke during occupant evacuations. Smoke can be removed using natural and powered exhaust ventilators. The interior of the building is arranged so that the hot smoke and gases rise and collect in reservoirs under the ceiling, from where they are removed through the ventilators. Alternatively, smoke control using a pressure differential system or depressurization system can be used to maintain a smoke-free escape route. The aim is to keep smoke at a safe height above the heads of occupants who are using the escape route while the fire is burning.
The start of any fire must be detected as quickly as possible, and certainly before it can make the means of escape unusable. In some circumstances, particularly where occupants are located away from the origin of the fire and there is a reasonable possibility that it could spread, this means that the fire must be detected and occupants alerted within the first minute of ignition. This will allow building occupants enough time to escape. Regardless of the location, once occupants become aware of a fire they must be able to proceed safely along recognizable escape routes to a designated location. In order to achieve this aim, it is mandatory to protect the route with fire-resisting construction. Legislation for specials needs occupants includes specific requirements regarding the means of escape in case of fire. Building operators must make any necessary adjustments to their premises to ensure that no occupant is at a disadvantage during an evacuation. Every commercial, industrial or institutional building has an approved fire safety plan which clearly identifies the obligation to account for special needs occupants. The plan must list those with physical and/or mental limitations, the nature of the assistance they may require, and customized emergency evacuation procedures.
This article was contributed by Firepoint Inc, serving the GTA since 1997, developing fire department approved fire safety plans for newly constructed and existing buildings. Although every effort is made to ensure the accuracy, currency and completeness of the information, the bulletin publishers and authors do not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current and shall not be liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the bulletin information. Bulletin reproduction in whole or in part is prohibited without the written consent of Firepoint Inc. Copyright 2021 – All Rights Reserved. See www.firepoint.ca or call 905-874-9400.