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Fire Engineering Techniques & Services

FCS-live use the latest fire engineering techniques such as CFD smoke modelling and evacuation modelling.

Fire engineering

Fire engineering

Smoke Modelling

Smoke modelling is a technique for simulating the way smoke and heat will behave in the event of a fire.

In certain types of building, such as internal corridors in residential blocks using mechanical ventilation, shopping centres or buildings with a n atrium, smoke modelling is likely to be required as part of the standard design process and for approvals.

In others, it might be used as part of a fire engineering justification for a building (an example could be to justify extended travel distances).

There are two main types of Smoke Modelling:

Zone smoke modelling is a technique that is based on equations derived from practical experiments. For the building that is being considered, as long as the physical geometry and possible fire scenarios are within the limitations of the fire tests that have been carried out, zone smoke models are a perfectly acceptable way to predict the likely smoke flow rates.

Zone models have the advantage that they are relatively simple and quick to carry out. However, if the building shape or fire scenario are outside the limits of the experiments that were carried out, zone models cannot be used. They are therefore only useful in certain specific situations, but in those situations they give quick, simple and accurate results.

Computational Fluid Dynamics (CFD) Smoke Modelling is a very different approach. The basis of the technique is that the spa ce that is to be modelled has a (3D model) built into a computer program, which breaks the space into a large number of individual cells (typically hundreds of thousands). The computer program then uses fundamental laws of physics and fluid flow to analyse the flow of the air and smoke between each cell for the duration of the fire.

CFD analyses take time to set up within the computer simulation, and each analysis can take several days to run, even on high specification computers. However, they can analyse smoke flow in a much wider range of scenarios. They also provide a 3D view of smoke travel, velocity and tenability for Fire Brigade access which is easy to interpret and widely used by enforcing authorities.

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Evacuation Modelling

There are a number of different ways to analyse the evacuation of buildings, our team can advise you on which is the most appropriate approach for your premises.
Standard fire safety guidance documents typically specify the width of exit based on the number of occupants. Some guidance documents also incorporate factors such as the occupant characteristics and the fire risk within the building to modify those figures. These methods are useful, simple approaches that give reasonable results for most buildings.

However, in certain situations it is necessary to predict the amount of time needed to evacuate a building. This can be used in combination with smoke modelling, which can predict the time available before untenable conditions are reached.

The combination of these methods is often useful in unusual or complex buildings where the standard design guides would be inappropriate or compliance is impractical to achieve. By demonstrating that the evacuation is complete well before untenable conditions occur, engineers are capable of demonstrating that building designs are safe for occupants.

Computer Evacuation Modelling can combine these elements by way of a 3D model demonstrating evacuation of persons in real time, with the travel distances, exit routes and widths. This tool is particularly useful when the means of escape are complex, exit widths are difficult to achieve and the client wishes to maximise the occupancy. This method is often used to demonstrate evacuation in complicated buildings where Approved Document B is difficult to comply with and occupancy is required to be maximised.

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Pressurisation Systems

Often needed as part of a fire strategy for a building, the most common reason for a pressurisation system would be to protect a fire-fighting shaft (stair, lobby and lift) but they can also be used for other reasons, such as to compensate for non-compliances in other aspects of the design.

Whilst there are design codes available for pressurisation systems, it is essential that the design be carried out by people who have the relevant experience. One common mistake is to ignore the pressure relief that is needed on the occupied floor levels, without which the pressurisation system may not work correctly.

We have extensive experience in the design of pressurisation systems in a variety of buildings.

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Fire Suppression Systems

There are a wide range of fire suppression systems available for use within buildings.

Misting Systems are relatively new to the market, but provide systems for most types of buildings and use a reduced amount of water due to the droplet size.
Sprinkler systems are one of the most widely used systems and can be highly effective in controlling or extinguishing fires. This can have major benefits for fire safety, as well as reducing the potential damage to the building in the event of a fire.

Each type of system has their own advantages and disadvantages. Before specifying a system it is therefore essential to review what the purpose of the extinguishing system is, what the priorities are and then to identify the most appropriate solution.

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Fire Strategies

When developing a fire strategy for a building, we will always ensure that we are focussing on the specific needs of that particular project. Our engineers are experienced at guiding clients through the RIBA stages of design and construction for all fire safety matters. In some cases the client or architect may need support in order to gain approval for a design that doesn’t comply with standard fire safety approved guidance. In other situations the focus may be on value engineering to ensure that the building gains statutory approval at the lowest cost whilst still achieving safety.

The fire strategy will typically focus on issues such as:

  • The means of escape
  • Occupancy type, numbers calculations
  • Fire alarms
  • Emergency lighting
  • Elements of fire resistance of walls, doors, floors and structure
  • External fire spread to adjacent buildings
  • Fire-fighting facilities and access for fire brigade

The fire strategy may also include details of any fire engineering technique that has been used, such as smoke modelling, evacuation modelling, or structural fire engineering.

Fire strategies can also cover the construction process, showing how the standards of fire safety are to be maintained throughout all stages of the construction. This is particularly important when the work is being carried out whilst parts of the building are occupied, such as where a phased handover is being used, or where the work is being carried out on a partially occupied building.

Our specialist team have extensive experience in the preparation of fire strategy reports and guiding clients through approvals process for all types of buildings.

Fire engineering can sometimes provide an alternative way to design a building that avoids the need for automatic suppression. Our specialist team have the expertise to review the fire safety requirements for the building and recommend the most appropriate fire safety system.

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Existing Building Compartment Compliance Inspections

A more invasive and sometimes destructive inspections of the premises, compartmentation surveys identify and confirm the condition of the compartment walls and floors designed to protect means of escape and contain fire spread within the premises.

The building plans will be marked up with the lines of compartmentation, as well as any breaches which have been identified. A description of the breach, recommendation for remediation and a photo will be provided.

Compartmentation surveys are key to understanding the way a fire would travel through a building in the event of an incident. Converted premises and buildings containing sleeping accommodation commonly require compartmentation surveys to confirm that the building supports the evacuation strategy and meets the recommendations of the building regulations.

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During Construction on Site Passive Fire Compliance Inspections

During construction, we can conduct ongoing audits to monitor the installation of passive fire protection measures such as intumescent collars, air transfer grills, fire dampers, cavity barriers and intumescent coatings to structural steel work.

This provides the reassurance that these essential elements of fire safety design have been installed to the required standard.

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Pre-Occupation Surveys

Prior to hand over of a newly constructed or renovated premises, we can conduct a review of the fire safety arrangements with the aim that any potential fire-related issues may be resolved before the building is occupied.

The assessor will review the premises against the fire strategy and in accordance with the relevant fire safety guidance.

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For professional advice or further information, call us today on: 0333 0433 833