a) Assess Reaction:

· Evaluate the expected response and actions of building managers in relation to the evolving fire threat.

b) Determine Escape Provisions:

· Ensure adequate means of escape are provided based on the assessed reaction and time required for safe evacuation.

NOTE 1 Figure 2 shows an example of the relationship between the development of the fire threat and time.

Figure 2 Comparison of fire and time line development

Each building type should be allocated a risk profile (see Clause 6) depending on the occupancy characteristic and the fire growth rate associated with its use. The time to escape to a place of relative safety should be less than the allowable travel time (see Figure 3), which is based on the risk profile.

Figure 3 Occupant response and travel time

Screenshot (36).png

Stages of Occupant Response for Means of Escape

1. Time to Detect and Alarm:

· Time from ignition to detection and sounding the alarm.

2. Pre-Movement Time:

· Time from receiving the alarm to starting movement, including recognition and response time.

3. Travel Time:

· Time required to move to a place of relative safety, including any queuing.

4. Movement Within Safety:

· Movement within a safe area (e.g., protected stairway or compartment).

Key Considerations

1. Escape Capacity:

· Ensure sufficient escape capacity for all occupants to reach safety without delay.

2. Compartmentalization and Smoke Control:

· Provide fire compartments or smoke control systems to allow safe evacuation and prevent smoke spread.

3. Occupant Behavior Insights:

4. Recognize that occupants may:

· Have difficulty recognizing fire threats in large spaces.

· Underestimate fire spread speed.

· Experience delays in evacuation due to late warnings and uncertainty.

NOTE 2 The relationship between these factors is shown in Figure 3. The objective is to limit the time taken to travel through those areas of a building which could potentially be exposed to fire and smoke.

NOTE 3 As shown in Figure 3, there are two primary early stages that occur before the occupants start to move to escape:

NOTE 4 The movement to escape in many cases might not be along the optimum travel route as predicted in the design, particularly in situations where occupants are unfamiliar with the building. This is less important in cases where queuing at a door is the primary control of the existing time. However, since no evacuation is perfect and human behavior can be uncertain, relatively slow travel speeds have been used to provide a margin of comfort to allow for potential unknowns.

NOTE 5 The place of ultimate safety is beyond the final exit but it is not always practicable or desirable to evacuate the whole of the building immediately upon the incidence of fire in any part. In large premises, it is sometimes practical and appropriate to evacuate in stages, which is also beneficial for escape for people with impaired ability to evacuate.

11 Principles of means of escape