Computational Fluid Dynamics (CFD) modelling is a cornerstone of modern fire engineering, transforming the way we design, validate, and future-proof buildings against fire hazards.
From high-rise residential towers to transport hubs and commercial atria, CFD modelling enables engineers to simulate fire and smoke movement in complex environments—before a brick is ever laid.
In this article, we explain what CFD modelling is, its applications in fire safety, how it aligns with UK regulations, and why it’s an indispensable tool for architects, developers, and building control officers alike.
What Is CFD Modelling in Fire Engineering?
CFD modelling is the use of numerical simulation to predict fluid behaviour—in fire safety, this means modelling how smoke, heat, and toxic gases move through a space during a fire.
It involves solving equations that describe the motion of air, heat transfer, and the effect of buoyancy under fire conditions.
These simulations:
- Predict smoke accumulation and spread
- Assess visibility and temperature thresholds
- Identify pressure differentials and airflow
- Support smoke ventilation and pressurisation system design
How Does It Work?
Using specialist software (such as PyroSim, FDS, or Fire Dynamics Simulator), a detailed 3D model of the proposed or existing building is created.
Then, fire scenarios are introduced based on real risk profiles:
- Fire location and growth rate
- Material combustibility
- Smoke production and exhaust ventilation
- Occupant evacuation times
The model runs thousands of iterations to simulate the movement of smoke and heat over time, producing visual and data outputs that engineers can interpret.
Applications of CFD in Fire Safety
Smoke Control System Design
CFD is integral in validating the effectiveness of mechanical smoke ventilation (MSVS).
Evacuation Modelling Support
CFD can be integrated with egress modelling tools to ensure visibility and temperature thresholds remain tenable during occupant escape.
Complex Architecture
In buildings with open-plan atria, tunnels, or interconnected floors, CFD provides insights that prescriptive code methods cannot.
Gateway One, Two & Three Submissions
CFD results are frequently used to support planning applications and safety case reports under the Building Safety Act and gateway review process.
Regulatory Alignment
CFD modelling is recognised in:
- Approved Document B: For complex fire engineered solutions
- BS 9999: As part of a fire safety engineering approach
- BS 7346-8: For designing smoke control systems
- BS EN 12101 series: Governing smoke and heat exhaust ventilation
- Building Control and planning authorities increasingly expect CFD-backed justifications in non-standard or high-risk buildings.
Benefits of CFD Modelling
- Enhanced Design Freedom: Allows innovative architecture without compromising safety
- Performance-Based Design: Go beyond prescriptive limits with evidence-based strategies
- Risk Mitigation: Identify design flaws early, avoiding costly retrofits
- Authority Approval: CFD-supported strategies increase the likelihood of planning and building control approval
- Clarity Through Visualisation: CFD results are easy to interpret and powerful in stakeholder engagement
Why FDS Consult UK?
FDS Consult is one of the UK’s leading experts in CFD fire modelling, with:
- Decades of experience in complex residential and commercial projects
- In-house fire engineers, CFD specialists, and compliance advisors
- Proven success with Gateway planning stages and high-rise approvals
- Tools including FDS (Fire Dynamics Simulator), PyroSim, and Pathfinder
Use Cases
- Residential high-rise with mechanical smoke shafts
- Open atrium commercial spaces
- Underground car parks requiring impulse ventilation
- Façade and external fire spread validation (via radiation analysis)
Common Questions
When is CFD required in a fire strategy?
When the building design departs from prescriptive guidance or where smoke control systems must be justified based on performance.
Can CFD help with planning submissions?
Yes. CFD reports support Gateway One & Two submissions and are often requested by Building Control.
Is CFD approved by Building Control?
Yes—when conducted and presented by competent fire engineers with aligned assumptions and clearly documented outcomes.
CFD modelling is not just a technical add-on. It is the key to unlocking compliant, innovative, and future-ready fire strategies. From early design to final handover, CFD empowers teams to validate safety with confidence.
Contact Fire Consultants to discuss your fire modelling needs or request a sample CFD report.
