In modern building design, especially those with open-plan layouts, tall atria, or interconnected floors, understanding how smoke will behave during a fire is essential to ensuring safe evacuation and system performance. That’s where CFD smoke modelling becomes invaluable.
This article explores what CFD smoke modelling is, how it’s used to predict smoke spread, and why it’s a critical tool in validating fire strategies for complex buildings and building control approval.
What Is CFD Smoke Modelling?
CFD (Computational Fluid Dynamics) smoke modelling uses advanced simulation tools to replicate how smoke moves through a 3D environment during a fire.
Using inputs like:
- Fire size and growth rate
- Geometry and materials
- Ventilation systems
- Environmental factors (e.g. wind, stack effect)
a CFD model simulates:
- Smoke layer development
- Temperature profiles
- Visibility levels
- Pressure and airflow
When Is It Needed?
CFD smoke modelling is essential when:
- The building departs from prescriptive codes like Approved Document B
- Open atria, long corridors, or shared spaces complicate smoke flow
- Natural and mechanical smoke ventilation strategies need validation
- Evacuation modelling is required for phased or extended escape times
Key Outputs of a Smoke Model
- Smoke layer height: Identifies how fast smoke descends and when evacuation becomes untenable
- Temperature contours: Assesses risk to structural elements or suppression systems
- Visibility graphs: Helps define when routes become too obscured for safe escape
- Vent efficiency: Measures how quickly smoke is extracted and whether smoke control systems work as intended
Example: Atria in Commercial Buildings
In an open-plan commercial tower with a central atrium:
- A fire occurs on the fourth floor
- Smoke rises into the atrium and threatens upper-level walkways
- CFD modelling is used to test smoke extraction via high-level vents
The output shows that without supplemental extraction, upper floors experience visibility failure within 90 seconds. With a revised smoke control system, tenability is extended to over 6 minutes.
Visualising Risk
CFD visuals are powerful for:
- Communicating with project stakeholders
- Supporting Building Control and Gateway submissions
- Demonstrating strategy credibility during peer reviews
Typical visuals include:
- 3D isosurfaces of smoke spread
- Plan overlays showing tenable zones
- Time-sequenced animations of smoke migration
How FDS Consult UK Delivers CFD Smoke Modelling
- Experienced CFD engineers using FDS, PyroSim, and Fire Dynamics Simulator
- Full integration with fire strategy and egress models
- Regulatory-ready reports aligned to BS 7974 and BS EN 12101
- Peer-reviewed results where required by AHJs or insurers
- Visual packs suitable for planning submissions and design team review
CFD FAQs
Is CFD required by Building Control?
Not always, but for non-standard designs or complex smoke control strategies, it’s highly recommended.
How long does CFD modelling take?
At FDS Consult UK we work with our clients throughout the detailed design phase. The length of time it takes to complete the CFD will depend on the complexity and number of scenarios required for the project.
What information do I need to provide?
Architectural plans, fire load details, smoke control design intent, and MEP coordination notes.
FDS Consult CFD Smoke Modelling
CFD smoke modelling turns assumptions into certainty. In high-risk, high-value, or high-profile buildings, it provides the evidence needed to make smart, safe fire design decisions.
FDS Consult UK delivers regulatory-aligned CFD services backed by visual clarity and technical rigour.
Request a quote or case study to see how CFD smoke modelling can support your project.
