CFD modelling is particularly useful for projects where smoke movement, heat build-up or ventilation performance needs to be assessed in more detail. This can include complex buildings, atria, basements, car parks, shopping centres, warehouses, high-rise buildings, large open-plan spaces and buildings with unusual layouts.

It may also benefit projects involving smoke control systems, natural or mechanical ventilation, extended travel distances, performance-based design, or proposals that move away from standard prescriptive guidance.

By modelling different fire scenarios, CFD can help identify potential issues before construction or refurbishment work is completed.

CFD modelling can be accepted by Building Control when it is carried out properly and forms part of a clear fire engineering approach.

In most cases, Building Control will want to see that the modelling is based on sensible assumptions, realistic fire scenarios and a clear explanation of the results.

The study should also explain what is being tested, the acceptance criteria, and how the findings support the proposed fire safety design.

It is usually best to discuss the modelling approach with Building Control or the relevant approval body at an early stage. This helps ensure the scenarios, assumptions, and objectives are understood before detailed modelling work begins.

The time required for a CFD study depends on the building’s size, the design complexity, and the number of scenarios to be modelled.

A straightforward study may take a few weeks, while larger or more complex projects can take longer. Time is needed to review the available information, agree on the assumptions, build the model, run the simulations, check the results and prepare the final report.

Providing accurate drawings, fire strategy information, ventilation details and design objectives at the start of the process can help avoid delays.

CFD modelling may be needed where standard fire safety guidance does not fully answer the design question. This is often the case when smoke movement, heat exposure, ventilation performance, or tenability conditions need to be examined in more detail.

It may be used for buildings with large open spaces, complex escape routes, basements, car parks, atria, unusual geometries or bespoke smoke control systems.

The aim is usually to assess whether conditions are likely to remain suitable for evacuation, firefighting access, or the intended fire safety strategy across the selected fire scenarios.

A CFD study usually starts with accurate drawings and a clear understanding of the building layout, use and design objectives.

The information needed may include floor plans, ceiling heights, fire strategy details, proposed fire scenarios, ventilation information, smoke control arrangements, extraction rates, inlet air paths and details of how systems are expected to operate during a fire.

Where information is missing, assumptions may be made, but they should be clearly recorded. Better information at the start usually leads to a more useful and reliable modelling study.

CFD modelling supports fire safety design by giving a clearer picture of how smoke, heat and gases may behave in selected fire scenarios.

The results can help assess visibility, temperatures, smoke layer height, ventilation performance and the effectiveness of smoke control systems. This information can then be used to support design decisions, review potential risks and provide evidence for discussions with Building Control, design teams or other stakeholders.

It is especially useful where a project needs a performance-based fire engineering approach rather than a simple prescriptive solution.