A FIRST FOR COLT SMOKE CONTROL SYSTEM AT PARADISE ST/ LIVERPOOL ONE                                 VIEW AS PDF (5.4 mb)

In 2006 Colt won the contract for what was believed to be the UK's first smoke control system for a car park. It has been designed specifically to enable occupants to escape from a car park and to assist fire-fighting crews, rather than simply as a smoke clearance system that is commonly applied to car parks.

The £2.5 million project - part of Liverpool's £920 million Paradise Street retail, leisure and residential development - has involved the supply and installation of a Colt impulse car park ventilation system for the massive 56,000m², 2,000-space car park that is being built beneath Chavasse Park in Liverpool. BDP is the Architect, Laing O'Rourke is the Main Contractor, Crown House is the M&E Contractor and WSP is the Services Consultant. The Fire Consultant is Tenos Fire Safety Engineering.

The four-storey underground car park has been fitted with 80 Cyclone induction fans and 22 Jetstream impulse fans. These are designed to keep smoke completely away from the escape routes without the need for smoke curtains or physical barriers.

John Perry, senior consultant at Colt, explained: "Nearly all of the car parks we have done in the UK so far are smoke clearance systems, not smoke control systems. With the former, you have a designated extract rate. This car park is different because it is so large (with the largest level being 232m by 95m) that we have to move smoke from a potential fire into defined corridors. So, this is a fully designed scheme rather than a simple air change rate scheme. We are not merely clearing the smoke - we are controlling it."

Prior to the award of the contract, engineers from Colt and the Building Research Establishment demonstrated the effectiveness of the Colt impulse scheme for the Paradise Street project by conducting a series of hot smoke tests in a simulated car park in Middlesbrough. These established the accuracy of CFD modelling Colt had made before the test, and predicted that the scheme of impulse fans would be capable of controlling the spread of smoke from a car fire and keeping significant areas of the car park smoke free.

Glass and metal louvre screens
In a separate contract, Colt also provided a fixed glass and metal louvre system to the exterior. These items provide the ventilation for the car park, but also have an architectural purpose. With the UNESCO World Heritage Site of Liverpool Mercantile City adjacent to the car park, the combination of robust materials and light architectural elements, such as the louvre screens provided by Colt, makes them fit adequately in this context.

Colt's louvre screens feature on the east, north and south facades of the building. The aluminium louvres offer good outward visibility and transparency, provide a significant amount of daylight and the required natural ventilation. The angle of the louvre blades that clad the car park structure differ from floor to floor in order to prevent views in from the street level, and once again to provide natural ventilation. Colt's products have helped to establish the impression of a modern, transparent and light building that is fitting with the high status of the development itself and its environment.

Progress report for the car park ventilation system

Colt is handing over the system in April 2008 and the car park is due to open shortly thenafter.

For more information on smoke control systems for car parks, click here.

Design of smoke control systems for car parks

For larger car parks, a 'zonal' system must be used, so that, rather than creating an airflow across the whole width of the car park, the use of selective fans combined with appropriately located extract points enables the spread of smoke to be limited to a particular area of the car park.

In this example the fire is at the left of the red area and smoke is being blown towards the extract point shown in red in the bottom right corner. Only the impulse fans close to the fire operate.

It is important for the system to know exactly where the fire is to operate the correct fans and so there is more onus on the detection system.

Larger projects must use a "zonal" system - In a fire, the use of selective fans upstream of the fire forces the smoke towards the extract point