Room size limits when using a fire zone model for smoke-filling calculations, TR17 (2013)
- Valid from
- Information provider
- BRANZ Limited
- Information type
- Technical recommendation
This technical recommendation addresses the general applicability of a zone model's uniform property assumption within the smoke layer for different enclosure sizes. It suggests criteria intended to help the model user identify when the application of a zone model is more likely to generate acceptable estimates of the smoke-filling process within a room of fire origin of given dimensions based on a uniform smoke-filling assumption.
The criteria given are not relevant to sub-models that are not strongly influenced by the general smoke-filling process such as the ceiling jet characterisation and response of sprinklers or detectors using the ceiling jet properties.
The following guidance is intended to apply when using a fire zone model for smoke-filling calculations as part of an analysis conducted in accordance with the C/VM2 Verification Method: Framework for Fire Safety Design.
This guidance has been developed based on analysis using the BRANZFIRE zone model. It is also considered applicable to the B-RISK model and may additionally apply to other similar fire zone models. It is expected the guidance could be modified or improved with further research and ongoing comparisons with both experimental data and other valid models.
The guidance provided is intended to help fire engineers assess the suitability of using a zone model for a given combination of fire size and compartment dimensions. However, the criteria described should not be treated as absolute constraints as they are not the only factors that may affect the decision to use a zone model or not. The complexity of the building geometry and fire safety systems, the perceived risk associated with the design, and the fire safety objectives and purpose of the analysis may also influence the model selection decision. It is expected the engineer and peer reviewers will consider the full range of factors applicable to the specific building before agreeing on the appropriate model to use for a given analysis.