Smoke control systems can give more flexibility to your design, but they need to be used correctly. Read more.

1. When is smoke control needed in a car park?
Let me make it clear. I’m talking here about
systems providing smoke control, not just
smoke clearance as recommended in Building
Regulations. These systems are much more
complex and costly than compliant smoke
clearance systems, so why would anyone
choose to use them?
Smoke clearance or smoke control?
As always it comes down to fire engineering. If your car park is fully compliant with Approved
Document B (or its equivalents in Scotland and Ireland) then a simple smoke clearance system is all
that is needed. However, if the design you are considering is non-compliant, a jet fan based smoke
control system could be the way to achieve an equivalent level of safety.
When should you opt for a smoke control system?
The usual reasons for considering smoke control are:
 If you are not planning to provide a sprinkler system in those car parks where sprinklers are
required, such as car parks attached to shopping centres or located in London Section 20
buildings.
 If the car park doesn’t meet prescriptive maximum travel distances for means of escape.
 If you are planning a stacker type car parking.
Smoke control systems can give more flexibility to your design, but they need to be used correctly.
Good design calculations are critical
The benefit of a smoke control system is that it keeps designated areas of the car parkeffectively
smoke free, whereas a smoke clearance system may allow the whole car park to become smoke
logged. BS 7346-7 provides guidance on the requirements for smoke control systems, but its scope
does not include the necessary design calculations, which really do need to be backed up by CFD
analysis.
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2. The difference between smoke clearance and smoke control is
clearly shown in two videos. The first test carried out at Avon Fire
and Rescue Service showed how a smoke clearance system
slowly clears a smoke logged car park. A second test carried out
at BRE in Middlesbrough showed how impulse ventilation can
limit the flow of smoke to a predefined area, ensuring good
visibility is maintained throughout the car park, and how effective
a properly executed CFD analysis can be in predicting smoke
flows and temperatures. All the details of the test are available in
a leaflet you can download at the bottom of this page.
Upgrading from smoke clearance to smoke control
It’s not a trivial task to upgrade from smoke clearance to smoke control in car parks. In all but the
largest areas it is likely to require a significant increase in the ventilation rate with a concomitant
increase in plant and duct space requirements. Location of extract plant also becomes more critical, as
does the control strategy.
Smoke control systems are not a “get out of jail free” card but, used correctly, they can provide the
additional design flexibility required on some projects.
Car park smoke control in practice: Liverpool One
The car park of the Liverpool One shopping centre provides a very good example of a situation where
a smoke control system provided the most cost-efficient and effective solution. With more than 2,000
2
spaces split over a massive 56,000 m on four levels, the system is tasked with enabling occupants to
escape and assisting fire-fighting crews. For details on the project as well as the CFD models and
tests that were executed to show how the smoke control system would fulfil its mission in case of fire
please visit the Liverpool One project page.
Do you want to know more? Download additional information here!
If you want to know more about the relative merits of traditional ducted ventilation system, impulse
ventilation and induction ventilation, and the full details of the Middlesbrough test on smoke control
through impulse ventilation, visit our Car Park Ventilation page.
Paul is a Technical Director for Colt, experienced in smoke control, HVAC, solar
shading and louvre systems.
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