IFC have extensive experience in designing cost effective bespoke smoke control systems within all building and occupancy types.

Simplistically smoke control can be defined as;

“measures to control the spread of smoke and hot gases due to a fire within a building”.

When Would We Use Smoke Control?

To meet prescriptive codified requirements as indicated within BS 5588 Parts 1, 4, 5, 7, 10 and 11; or as part of a fire engineered solution.

• To maintain tenable conditions for escape purposes.
• To aid firefighting operations.
• For the protection of property.
• For the protection of business and insurance purposes

Smoke and Fire Dynamics Modelling

Calculating the spread of smoke and fire should be consideredwhen developing a fire safety strategy, allowing the Available Safe Egress Time (ASET) to be predicted for selected fire scenarios. Smoke and fire hazard calculations may be required also as part of a risk assessment or building engineering design process. While simple ‘hand calculations’ and ‘design guidance’ will suffice in many instances, larger more complex buildings and smoke management schemes require the use of computer modelling to more accurately predict the development of hazardous conditions following a fire.

IFC have a team of leading international design engineers with a wide experience in the application of all types of smoke and fire modelling and can offer this as a stand alone service or as part of a bigger project. This includes tools to predict the response of structures to fire and the use of one-dimensional network models to predict the movement of smoke in high-rise buildings, metro-tunnels etc where this is dictated primarily by the distribution of pressures associated with natural and mechanical ventilation, stack effects and vehicular motion.

Zone and CFD models are employed where smoke stratification or other two and three-dimensional effects may be important.

Zone Modelling

Zone models were developed originally for room fires, where the geometry is divided into a small number of approximately homogenous zones, e.g. cool lower layer, hot upper layer, fire plume. Employing a combination of fluid dynamics analysis and empirical relationships, the evolution of hazardous conditions, e.g. smoke layer height and temperature, is calculated. The methodology has been extended to more complex geometries such as shopping malls and atria, allowing ASET values to be generated for use in evacuation analyses.

IFC engineers use in-house spreadsheet programs to solve the zone modelling methodology documented in BS 7346, BR 368 and elsewhere <see Fig 1>. Third party zone models, including CFAST and ASMET form NIST, are also employed where appropriate.

Computational fluid dynamics (CFD) modelling

While network and zone models run very quickly on modern desk top computers, they include approximations in respect to the fluid dynamics and geometry. Computational fluid dynamics (CFD) provides a more rigorous, three-dimensional treatment where the underlying conservation equations are solved on a numerical grid containing typically tens or hundreds of thousands of points. A solution ‘picture’ comprising temperatures, smoke concentrations, air velocities etc at each grid point is generated. This allows the engineer or designer to assess in detail the interaction of fire and smoke with building designs and smoke control systems of arbitrary complexity, and to study the implications for means of escape.

IFC engineers employ a range of CFD fire models including the JASMINE model from BRE and the Fire Dynamics Simulator (FDS) model form NIST, selecting the model most appropriate for the task at hand.

CFD takes considerable experience to use correctly, and this experience has been built up at IFC over many years. Some examples of projects where CFD has been employed include large atria spaces (Left), exhibition halls and car parks. With the advent of performance-based design, CFD is being used increasing as a tool for fire safety engineering.

Combining egress modelling with CFD represents the cutting edge of fire modelling. This was employed in the combined smoke spread and evacuation modelling for an airport terminal. Other advanced areas of application for CFD models include the interaction of smoke and fire with sprinklers and in coupling with finite element models to predict the thermal and structural response of building elements.

Please contact us so that we can customise a suitable smoke control system, packaged to meet your needs and expectations.

To view recent examples of IFC’s CFD work click here