Quantification in NCC 2022 Volume 2

The introduction of the National Construction Code 2022 in May 2023 heralds the introduction of new quantified Performance Requirements in Volume 2. NCC 2022 H3P1 and H3P2 (BCA 2019: P2.3.1 and P2.3.2) now include quantified metrics for spread of fire and automatic warning of occupants. H3P1 is quantified with appropriate fire safety design metrics. H3P2 is quantified using an effectiveness metric. This metric combines efficacy and reliability.

BCA 2022 H3P1 has been reproduced in Figure 1 and BCA 2019 Amendment 1 P2.3.1 has been reproduced in Figure 2, with the clear difference being the reference to 92.6 kW/m2 and the introduction of a design probability.

The reference to the 92.6 kW/m2 thermal radiation can be traced back to the Verification Methods in NCC 2019 Volume 2 Amendment 1, as shown in Figure 3.

Figure 1 – BCA Performance requirement H3P1 in NCC 2022 Volume 2

Figure 2 – BCA Performance requirement P2.3.1 in NCC 2019 Volume 2 Amendment 1

Figure 3 – Verification Method V2.3.1.1 and V2.3.1.2 in NCC 2019 Volume 2 Amendment 1

What Does This Mean for Performance Solutions?

Currently, many Performance Solutions for Class 1 and Class 10a buildings deal with openings in the external walls that are located within 900 mm of the allotment boundary.

Utilising NCC 2022, whilst the wall can be designed to comply with the Deemed-to-Satisfy requirements of Section 9.2 of the ABCB Housing Provisions, the openings would effectively need to be protected in some manner.

This is further compounded by the probability criteria which requires analysis of the provided fire safety measures and the likelihood of a fire occurring within the compartment. The latter would further warrant updated statistical data to develop probabilities to use the analysis to determine the likelihood of fire spread exceeding the threshold value.

The subject quantification of NCC Performance Requirement H3P1 (previously P2.3.1) represents the first steps in the adoption of quantified Performance Requirements in the NCC.

In comparison to NCC Volume Two, NCC Part A8 represents the quantification of Performance Requirements in NCC Volume One. It provides new risk and probability metrics to be used in interpreting the fire safety Performance Requirements. However, the adoption of A8 has been delayed and not included in NCC 2022. It is likely to be introduced in future versions of the NCC.

Hence, the introduction of NCC 2022 will provide Fire Engineers throughout Australia with a practice run in preparation for the full adoption of NCC Part A8 in the future.