Building/Use Parameters

BU1) Purpose Groups

The term “Purpose Group” covers the occupant type in a building and the activities they may be undertaking. This is an important parameter in a safety/risk analysis as the type of person and their activities will affect how they respond to fire cues and/or alarm and the length of time it takes for the person to escape the building. Therefore this parameter essentially assesses the human behaviour aspect of fire safety. The four key elements under consideration are:

• Alertness – awake or asleep, noisy environment or quiet?

• Familiarity – regular user, resident or casual visitor of the building?

• Capabilities – Physical (How fast can they walk, do they need assistance?) – Psychological (Will they think clearly or be confused?)

For this project it is assumed that we are assessing the safety of an average person who is fully ambulant, is capable of looking after themselves and following authoritative instructions if necessary. It is assumed that variance in individual capabilities is accounted for in the C/AS1 Purpose Group categories, e.g. children will be under the guidance of an adult and disabled persons will have access to appropriate facilities or assistance in the event of a fire emergency. Therefore variance in individual capabilities will not be specifically assessed. A simple independent ranking scheme based on a scale of 0 to 2 was derived by judgment to assess alertness, familiarity and occupant density of each purpose group to determine the points scored for each purpose group type. Alertness is considered the most important of the three factors and as such was weighted by a factor of 3. This was done to account for the fact that sleeping persons could take considerably longer to respond to an alarm than a person who is awake and/or familiar with a building. The results are shown in Table 6.1 below:

Purpose Group Alertness (x3) Familiarity (x1) Occupant

Density (x1)

Status Score Weighted _Score Status Score L/M/H Score

Total Score Scaled Score Sleeping Accommodation

SA Asleep 0 0 Unfamiliar 0 Low 2 2 1.1

Sleeping Residential SR

Asleep 0 0 Familiar 2 Low 2 4 2.2

Crowd

CS/CL/CM Awake & Noisy 1.5 4.5 Unfamiliar & Familiar 1 High 0 5.5 3.1 Working

WL/WM Awake 2 6 Familiar 2 Medium 1 9 5.0

Note: The crowd alertness has been reduced by 0.5 points to account for the fact that crowd environments can be noisy.

A similar scoring method was proposed by Sime (49) for deriving efficiency scores for determining pre-movement times for various occupancy types. The method is more comprehensive than the method used above and includes eight factors as follows:

B. Alertness - awake or asleep

(1 = asleep, 5 = fully alert). C. Mobility - disabilities

(1 = low mobility, 5 = high mobility). D. Social Affiliation - alone or in a group (e.g. family)

(1 = group, 5 = alone). E. Role - ratio of public to staff

(1 = public, 5 = staff).

F. Position - lying, sitting, standing or moving (1 = lying, 5 = moving).

G. Commitment - to what degree are people committed to finishing a task (1 = high, 5 = low).

H. Focal point - are all people focusing there attention on one point (1 = none, 5 = focused).

I. Familiarity - how familiar are people to the building (1 = unfamiliar, 5 = familiar).

The points are attributed on a scale of 1 to 5. There are no independent weightings so each item is weighted the same. Efficiency ratings for the purpose groups under consideration in this study were assessed as shown in Table 6.2 below for comparison to the Table 6.1:

Purpose Group B C D E F G H I Average SA _{1 3 1 1 1 4 1 1 1.6} SR _{1 3 5 3 1 4 1 5 2.9} CS/CL _{4 3 3 1 2 4 4 3 3.0} CM 4 3 3 1 5 2 4 3 3.1 WL/WM _{5 3 5 5 3 3 3 5 4.0}

From Table 6.2 the Sime method give the same ranking order as the ranking scheme shown in Table 6.1, however the point differential is not as wide with the score ranging from 1.6 to 4.0. (Table 6.2), as compared to 1.1 to 5.0 (Table 6.1). Either ranking could be used in this model however as some of Sime’s attributes are not applicable to the sleeping purpose groups, e.g. Role (E), the attributes scores will be derived based on Table 6.1.

Given the above the attribute scores are shown in Table 6.3 below:

BU1 – Purpose Group

Purpose Group As

SA 1 SR 2 CS/CL/CM 3

WL/WM 5

Table 6.3 – Purpose Group Attribute Scores

BU2) Building Escape Height

The points will be assigned in linear manner as shown in Table 6.4 below:

BU2 – Building Escape Height

Escape Height As Over 58m 0 46m < He ≤ 58m 1 34m < He ≤ 46m 2 25m < He ≤ 34m 3 10m < He ≤ 25m 4 4m < He ≤ 10m 5

BU3) Occupant Numbers

The points will be assigned in linear manner as shown in Table 6.5 below:

BU3 – Occupant Numbers

Occupant Numbers As Over 1000 1 501 < Occ. No. ≤ 1000 2 101 < Occ. No. ≤ 500 3 51 < Occ. No. ≤ 100 4 Occ. No. ≤ 50 5

Table 6.5 – Occupant Number Attribute Scores

BU4) Fire Hazard Category

The Fire Hazard Category (FHC) is a numerical grading from 1 to 4 as noted in Section 4.2.1. C/AS1 defines each category by a Fire Load Energy Density (FLED) which varies linearly between 0 and 1500 MJ/m2 for FHC 1 to 3 respectively and FHC 4 for FLED over 1500MJ/m2. Therefore the points will be assigned in a linear manner as shown in Table 6.6 below:

BU4 – Fire Hazard Category

FHC As

4 0 3 1 2 3 1 5