Building Risk Profiles - An Introduction

Building Risk Profiles are a fairly straightforward way of categorising buildings from a fire safety point of view, yet a concept that many fire risk assessor interviewees are surprisingly unfamiliar with. This article provides an introduction to the concept.

Risk Profiles

The building risk profile is a concept derived from BS9999:2017 Fire safety in the design, management and use of buildings – Code of practice.

The risk profile is a composite of two factors, the type of occupancy, and the fire growth rate. So a building with the risk profile A1 benefits from occupants who will be awake and familiar with the building, and limited combustible material, where one with C4 contains sleeping occupants and large bulk storage of combustible material (Note B4 and C4 are not acceptable under BS9999).

Table 4

Occupancy Characteristic	Fire Growth Rate	Risk Profile
A Occupants who are awake and familiar with the building	1 Slow	A1
	2 Medium	A2
	3 Fast	A3
	4 Ultra-Fast	A4
B Occupants who are awake and unfamiliar with the building	1 Slow	B1
	2 Medium	B2
	3 Fast	B3
	4 Ultra-Fast	B4
C Occupants who are likely to be asleep	1 Slow	C1
	2 Medium	C2
	3 Fast	C3
	4 Ultra-Fast	C4

Note that according to 6.5 of BS9999 automatic sprinkler systems provide an efficient means of controlling fire within a compartment, and as such the fire growth rate can be lowered by one level in the sprinklered rooms. This reduction should only be applied where the sprinkler system has been installed to BS EN 12845 (new) or BS 5306-2 (existing).

Why are building risk profiles important?

When applying the principles of BS9999, buildings with higher risk profiles generally require lower levels of protection, can afford higher exit capacity, and support longer travel distances compared to buildings with lower risk profiles. As such the building risk profile talks directly to level of control required when applying BS9999.

We will return to this principle in much more detail in later later articles.