Commercial Vehicle & Car Park Ventilation Systems
It has long been recognised that the ventilation of parking facilities, particularly those which are fully enclosed is expensive to both install and to operate; therefore, experience and an ability to think creatively in the design of such systems is essential; all those qualities exist in the Advanced Smoke Group.
The Advanced Smoke Group employs the most experienced specialists in the country to provide up to date, economical and creative solutions to the ventilation of vehicle parking areas.
Advanced Smoke Group is not bound by the restrictions of a fan manufacturer wishing only to sell their own products range; our engineers will design a system that is most suited to the project in question.
There are a number of options available from us:
- System design and CFD modelling
- Ducted ventilation systems
- Impulse or jet fan systems
- Induction fan systems
- Assisted natural ventilation or full mechanical systems
- Fixed or variable rate day to day ventilation
- CO and LPG gas pollution monitoring
- Smoke clearance or smoke control
- Manually activated systems for smoke clearance or automatic addressable multi-criteria fire detection
- Code compliant or fire engineered solutions
- Liaison with the regulatory bodies
Whichever option is required, however large or small the facility is, the Advanced Smoke Group can provide a solution.
New standards and guidance notes from organisations such as BSI, CEN and the Smoke Control Association are now appearing on a regular basis and we are not only aware of these developments but we are also involved with these groups assisting in the creation of the latest guidance; we are therefore able to ensure that our clients benefit from the latest technology and standards available..jpg)
Ventilation Options for Vehicle Parking Facilities
Ventilation may be provided in any one of three ways:
- Natural Ventilation
- Assisted Natural Ventilation or
- Full Mechanical ventilation
Natural Ventilation
If 5% of the net floor area of the car park can be provided in openings direct to atmosphere and 50% of these openings are on opposing walls then the car park may be classified as naturally ventilated in accordance with Building Regulations Approved Documents F (daily vent) and B (fire).
Assisted Natural Ventilation
If 5% of the net floor area of the car park cannot be provided in openings direct to atmosphere but 2.5% can, with 50% of these openings are on opposing walls then the car park may be classified as one suitable for assisted natural ventilation in accordance with Building Regulations Approved Document F (daily vent) and naturally ventilated in the case of fire, i.e. AD B (fire).
In this case, mechanical assistance must be provided to the natural ventilation under day to day conditions in order to compensate for the lack of buoyancy to aid ventilation. In a fire situation, the natural buoyancy of the hot smoky gases will aid ventilation and no mechanical assistance is normally required.
The mechanical assistance provided to support the day to day ventilation requirements should provide three air changes per hour to comply with the requirements of Approved Document F of the current building regulations; however, the requirement may also be met using jet fans to enhance the crossflow ventilation provided by the available natural ventilation. This form of ventilation may also be enhanced by the use of carbon monoxide monitoring to control the ventilation system.
Mechanical Ventilation
Where there is inadequate natural ventilation, a full mechanical system must be provided. This may be achieved using one of two options:
- Ducted Ventilation
- Jet Fan Ventilation
There are also two types of jet fan, the induction fan shown right and the impulse fan shown below.
Either fan can be used for smoke clearance but the impulse type fan is usually the most suitable for smoke control due to its improved discharge arrangement.
Ducted System
In the case of a ducted system the ductwork must be appropriately distributed within the car park to ensure adequate distribution of fresh air and provide 50% of the extraction at low level and 50% at high level; this will provide for exhaust emissions and for smoke extract.
The system should be designed to provide 6 air changes per hour for daily ventilation and 10 air changes per hour for smoke extract in the event of fire.
Jet Fan Ventilation
Sometimes referred to as Impulse Fan, Induction Fan or Thrust Ventilation. There are two options available in the jet fan type system:
- Smoke clearance and
- Smoke control
Smoke Clearance
Basically, the system will work on the same on the same principle as a ducted system with the jet fans replacing the ductwork with the fans being distributed at soffit level within the car park in such a manner that fresh air will be adequately distributed throughout the car park.
Main extract fans will still be installed to provide the necessary rate of fume extract.
Smoke Control
This system will operate in a similar manner to the smoke clearance option but with three significant differences:
- The system will be linked to a fully addressable fire detection system (smoke, multi-criteria or sprinkler flow switches)
- The jet fans will be installed in such a manner that they can control smoke flow 9this may involve a greater number of jet fans)
- The rate of extract will not be restricted to 10 air changes per hour but linked to an extract rate necessary to remove the mass of smoke generated by an appropriate fire load and creating an adequate velocity within a pre-determined smoke corridor such that the flow of smoke can be controlled.
The benefits of this type of system are that it can compensate for the lack of sprinklers, the need to ventilate lobbies adjoining the car park and increased travel distances; all these relations are of course subject to the agreement of the regulatory authorities on a case by case basis.
Equipment
The regulations and standards relating to the products used for ventilation will, of course, be dependant on which form of ventilation is adopted; for example, the fans used for providing the necessary assistance to the day to day natural ventilation in an assisted natural ventilation system need not be fire rated as they will be turned off in the event of fire.
Fan used for any aspect of smoke clearance or control must be fire rated and tested in accordance with BSEN12101-3 to verify their suitability for such an application. All fans used for smoke extract in a car park, loading bay or coach park ventilation system must be rated for at least 300ºC for 60 minutes.
Fire Rated Smoke Extract Fans in a Car Park
Cabling serving any component relating to the smoke extract system, whether fire detectors, fans or dampers etc. must be appropriately fire rated and their must be a secondary power supply (e.g. generator) to take over should there be a failure of the primary supply.
Ductwork and its fixings should not have a melting point of less than 8000ºC and, if passing through another compartment it should be fully fire rated to the standard of fire rating to which the compartment it is passing through is constructed.
Dampers and attenuation used within the system must also be suitably constructed for the application.
Monitoring Systems
Carbon Monoxide Monitoring
One of the most significant aids to saving on operating costs and energy consumption is the installation of carbon monoxide (CO) monitoring. CO monitoring enables the ventilation system serving the car park to react to the actual conditions prevailing within the car park.
The current building regulations state that carbon monoxide pollution levels should not exceed 30ppm when averaged over a period of 8 hours and at no time should exceed 90ppm for more than 15 minutes.
CO monitors can feed information directly to the car park ventilation control system enabling the system to quickly respond to rises or falls in pollution levels and can even enable the ventilation system to shut down completely in certain circumstances.
Fire Detection
There are, of course, a number of detection systems available for fire, the most commonly used are:
- Manual activation – the least reliable option as it relies entirely on someone being present in the car park when a fire starts and then on them having the presence of mind in that situation to activate the fire alarm
- Addressable Heat detection – this relies on the fire emitting sufficient heat to activate the fire detector which, in the case of a vehicle fire, can be some time before activation occurs; however, this will tell you where the fire is.
- Multi-criteria fire detection – this type of system provides the benefit of quick response by detecting both heat and smoke and will give the quickest activation whether heat or smoke is detected.
Computational Fluid Dynamics (CFD) Modelling
The ability to present a design in a graphical format to enable the design intent and predict the performance of a system design can be invaluable. The Advanced Smoke Group has the capability to provide such design support, the scope of which is demonstrated below:
Fire Spread in Car Park
Based on the latest BRE test data, current modelling techniques can provide increased insight as to the spread of fire between vehicles without expensive fire tests. Specifically this is of interest when considering the impact on the local built environment, escaping occupants and the logistics of fire spread prevention using suppression systems.
Smoke Control in Car Parks
In line with the BS 7346 part 7, the efficacy of a proposed fume / smoke control design can be demonstrated using CFD modelling techniques.
These modelling techniques are commonly used to demonstrate the effectiveness of jet fan solutions to control and contain smoke and facilitate egress and fire service access.
Loading bay fires
High hazard or areas of special consideration may represent a significantly larger fire loading than from a typical car fire scenario.
This may be seen in car parking areas that contain loading bay areas, or refuge collection areas where HGV’s may regularly circulate.
These high hazard scenarios can be modelled to provide insight as to the likely impact to the local built environment
Natural ventilation Solutions
Natural ventilation solutions for CO fumes and fire can be carried out using CFD modelling techniques. This will often be based on the available microclimate data and can include additional analyses to determine the impact on adjacent buildings or ventilation systems;
Ventilation of Loading Bays & Coach Parks
The design of ventilation systems for loading bays and coach parks is less straight forward than may be realised as there is little current guidance for this application. BS7346: Part 7 was written for car park ventilation and specifically excludes guidance for “lorry parks and coach parks”.
The current building regulations refer to the guidance for enclosed car parks and even BS9999 currently refers the reader back to BS7346: Part 7 which, as already mentioned specifically excludes guidance for “lorry parks and coach parks”.
To assist in overcoming this difficulty, the Smoke Control Association is due to publish a guidance document for the ventilation of Loading Bays and Coach Parks and this will include guidance on “fire engineered” solutions with suggested design fire loads.
Standards & Regulations
There are a number of documents relating to car park ventilation:
- Approved Document F of the current Building Regulations which covers day to day ventilation and limitations on maximum permissible pollution levels.
- Approved Document B of the current Building Regulations which covers ventilation requirements under fire conditions for England & Wales
- Scottish Building Standards Technical Handbook which covers ventilation requirements under fire conditions
- Technical Booklet E which covers ventilation requirements under fire conditions in Northern Ireland
- BS7346: Part 7: 2006 which sets out guidance on designing smoke ventilation systems for car parks including smoke clearance and smoke control systems for aiding fire fighting and means of escape
- CFD Modelling for Car Park Ventilation Systems which provides guidance for design engineers and regulators on the preparation and interpretation of CFD models.
- Local Regulations, there are many local acts such as the LDSA Section 20 Building Act for London which cover the ventilation of car parks
In addition to these documents there are a number of further documents being prepared for publication and which relate to the ventilation of parking spaces. Forthcoming documents include:
- Smoke Control Association Guide to the Ventilation of Loadings Bays and Coach Parks which is specifically excluded from BS7346: Part 7
- CFD Modelling for Car Parks, Loading Bays and Coach Park Ventilation Systems where the current SCA guidance booklet does not cover the loading bays and coach parks
- BRE Report on Fire Spread in Car Parks this document covers research into the risks associated with car park fires and the influence of sprinklers and the use of stacker systems
Book a Free ASG CPD Seminar
Members of the Advanced Smoke Group team have been involved in the design and installation of car park ventilation systems for well over 10 years, in fact, not only have we been involved since the introduction of impulse ventilation to the UK, members of the team wrote the first ever guide to the design and installation of impulse ventilation.
Team members are also active in contributing to the development of a wide range of standards and guidance documents through BSI and the Smoke Control Association.
With this background, we are able to speak with authority on the subject of car park ventilation, bringing together the latest practices and techniques in the design of such systems.
The Advanced Smoke Group seminar covers:
• The options for car park ventilation (not just jet fan systems)
• The background to jet fan systems
• Criteria for system design
• Design and objectives for smoke control
• Car park fires
• BRE Research into fire spread in car parks and its implications
• Impact of stacker systems on ventilation system design
• Latest guidance on ventilation of loading bays and coach parks
To book a free seminar at your own offices e-mail mail@advancedsmoke.co.uk or call 0116 271 6861 and we will be only too pleased to arrange a mutually convenient date.