Understanding Smoke Movement Within a Building
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Understanding the Value of Smoke Modelling
The time taken between the ignition of a fire and the onset of life threatening conditions in a building is the maximum time that occupants have to move to a place of safety. It is usually smoke from a fire that hinders the occupant evacuation and therefore it is important for our experienced engineers to understand the principles of smoke movement in buildings. In simple cases, generic models such as zone modelling techniques can be used to establish the smoke development and movement within a building, however in cases where unique architectural features or increased design complications such as jet fans form part of a building, we rely on more advanced modelling techniques to confirm the smoke movement and assess the impacts on egress.
Advanced Modelling: CFD
Computational Fluid Dynamics (CFD) modelling is a specific area of fire engineering that is used when zone modelling capabilities exceed their limitations. This occurs in larger, more complex buildings when a design requires more sensitivity analysis or confidence for approval. It can provide clearer representation of the smoke temperature, visibility and toxicity. With CFD modelling, more detailed information on the smoke can be generated in particular areas, taking into account the complex geometries and the ambient conditions in a space which may be sensitive to the overall fire engineering design.
The output produced by a CFD model are more visual than zone models as it can clearly show the environment through which people escape from the building. Results include three dimensional information on visibility of escape routes, velocity and direction of smoke flows, and temperature distributions within the buildings. This can be advantageous for a client to have reassurance for authorities in the approval process. The application of CFD also allows a detailed analysis and optimisation of smoke control systems in complex buildings; this applies in particular to optimise the locations of extract and supply air points and their required air volumes.
Fire Dynamics Simulator (FDS)
Using tools such as FDS means Holmes can undertake detailed analysis and optimisation of smoke control systems in complex buildings determining what smoke extract rate your building needs in order to provide adequate fire safety. In all but a few cases, the resultant smoke extract rate will be less than that specified by the building code and therefore enable the project to realise quantifiable cost savings.
How We Can Work With You
Our experienced engineers have a detailed understanding of fluid dynamics, affording them the ability to optimise the smoke exhaust design to suit the building geometry and features to minimise smoke spread. Holmes has specialist capabilities in CFD modelling for large warehouses and manufacturing plants, shopping centres, commercial buildings with connecting voids, atria and rail tunnels.