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a) Escape is permitted through an adjoining building or from one firecell to another. Fire separation requirements apply and protected paths may be required adjacent to exit ways. This is not critical to this project as only single buildings are to be considered and it is assumed that the final exit leads directly to a safe pace. Each floor of each building is assumed to be a single fire cell.

b) Basements can generally be treated like any other floor. The only exceptions are that where a basement shares a safe path with other floors then a protected path shall precede the safe path. Where such an arrangement serves three or more basement levels then the safe path shall be pressurised. The impact of basements shall not be assessed in this study.

c) There are minor restrictions and requirements in the code on obstructions in escape routes, direction of door swing, door sizes and handrail sizes. While these are important for the safe design of a building their impact on life safety is difficult to assess both qualitatively and quantitatively. For example all stairs must have a handrail. The impact of not having a handrail is likely to be a reduction of travel speed as persons of unsure footing descend more cautiously. However, this report focuses on the level of safety of buildings meeting the “code” and as such it is assumed that the above minor provisions are met.

d) Exitways shall not be used for storage of goods, solid waste or solid waste containers or points of entry for solid waste chutes. This is generally a matter of good housekeeping and as such exitways should be designed to avoid this. Therefore the impact on life safety of obstacles in exitways is not considered further in this study. e) Other activities, such as a reception, are permitted in an exitway providing that an

alternative escape route is available, an alarm system is installed and other activities have a FHC not greater than 1; the escape route is not impeded, activities (with the exception of ablution facilities) are visible to occupants and exist only to provide support to the purpose group users. It is assumed that all these provision are met when assessing safety of buildings in this study.

f) Lifts are not typically relied upon as a means of escape during a fire event in New Zealand.

g) Refuge areas are required in tall buildings (over 58 m escape height). They are usually contained within the vertical safe path stairs. Refuge areas are designed to remove congestion, allow slow persons to rest or be passed by quicker persons. They are not designed with the intention of a person waiting out a fire emergency.

h) Single escape routes can only be used in limited situations for purpose groups CS, CM, CO, WL, WM, WH, WF, IA and ID, SA and SR; and where total occupant load from all firecells on each level is less than 50 persons; and number of young children or disabled persons on any one floor is less than 10. Height restrictions apply as shown in Table 4.7 below.

Purpose group Escape height Max. FHC Sprinklers Installed

<4.0 m <3 No <10.0m <2 No <10.0m <3 Yes CS, CM, WL, WM, IA, ID <25.0m <2 Yes <10.0m - No SR and SA <25.0m - Yes

Table 4.7 - Height Restrictions for a Single Escape Route

The presence of a single means of escape has a significant impact on the safety of a building and the ability of occupants to escape a fire. Occupants do not get a choice of means of escape with a single escape route and as such C/AS1 looks to minimise the risk by introducing additional safeguards to ensure as far as practical that the escape route remains tenable for a sufficient time to enable all occupants to escape.

The two key elements for reducing the risk are:

• Limiting the total number of persons, and

• Additional passive fire safety features to extend the time to untenable conditions in the safe path.

The lowest occupant number category assessed in this study is up to 100 people, therefore single means of escape building are not applicable. A separate occupant number category would be required limited to a maximum of 50 persons. Therefore single means of escape buildings were not assessed in this study.

i) There are several life safety issues that need to be considered when evaluating the impact of doors on the safety of buildings in fires. These are:

• Fire and smoke control doors are required to perform a function during the course of a fire event. This function is to maintain the integrity of the fire/smoke barrier by preventing the ingress of fire or smoke into the exitway and ensuring the exitways remain tenable until the occupants have escaped. To achieve this, doors need to be fabricated and installed correctly and maintained and used properly. Hold-open devices are required to be used where there are more than 1000 occupants in a firecell and for doors between vertical and horizontal safe paths in sleeping purpose groups.

• Doors must be able to be opened with minimal force and not impede the flow of escaping occupants.

• Final exit doors must be able to be opened without the need to stop and unlock the door or remove impeding security measures.

The above items are paramount to the safe evacuation of persons from a building fire. Failure of any of these aspects may result in unacceptable risk to the occupants during the course of escape with safe and protected path filling with products of combustion early in the fire event or unacceptable levels of queuing or backtracking of escapees.

It is assumed that fire and smoke control doors are installed and used properly, therefore the adequacy of doors is not assessed as a specific item in the risk model developed in this study.

j) Some buildings require emergency lighting in exitways and, for larger occupant numbers and certain purpose groups and escape heights, in open paths as well. All buildings require exits to be clearly signposted.

The visibility of egress routes and adequate signage is an important aspect of fire safety design as it affects the ability of persons to find their way out of a building and as such impacts the travel time for escaping occupants.