ColtShaft is a mechanical fire-fighting shaft system that provides equivalent performance to a BRE shaft for the ventilation of common corridors and fire fighting lobbies. It can therefore be considered to meet the recommendations of Building Regulations (E&W) Approved Document B, BS 9991 and BS 9999 for ventilation of stair cores.
Under design conditions with the lobby doors open, ColtShaft provides a ventilation rate similar to the BRE shaft, but it also offers the benefit of being a lot smaller, providing 20% of the BRE Shaft footprint.
Watch our video which describes how ColtShaft was developed and shows how it works.
ColtShaft requires a shaft with a cross sectional area which can be as small as only 0.6m² compared with 3m² for the BRE shaft or 1.5m² for a natural residential (ADB) shaft.
This represents up to 80% reduction in the floor space required. It opens up the space on each floor, which allows architects to be more creative in their design, and improves the saleable or lettable space for the client. This in turn increases the profits for developers and the income for landlords, and permits more usable space.
ColtShaft can perform better than a BRE Shaft since it extracts at a defined rate - this means that it is unaffected by external wind pressures. It is also less susceptible to obstructions to the airflow within the duct.
The ColtShaft design has been proven by extensive CFD analysis and by empirical tests.
There are two types of ColtShaft, the ColtShaft Variable and the ColtShaft Constant.
The ColtShaft Variable incorporates duty and standby variable speed extract fans with inverter drive, linked to pressure sensors within the lobby and corridor at each level via the control panel. A motorised damper or flap is provided between the shaft and the lobby/corridor at each level. A 1 m² ventilator is needed in the stairwell for air inlet.
The pressure sensors maintain acceptable pressure difference between the lobby and stairs, typically at 25Pa. This ensures that excess pressures do not draw extra smoke past door seals or cause excessive door opening forces.
The ColtShaft Variable system is a LABC Registered System because of its superior performance as proven by CFD, thereby providing prior assurance of Building Control Approval.
The preferred design of mechanical shaft for apartment buildings is the ColtShaft Variable. However, not all clients are prepared to make the investment needed for this system. The ColtShaft Constant provides equal or better ventilation, but at the expense of potentially compromising compartmentation and of reverse hanging escape doors to open against the direction of escape. It has a lower initial cost.
The ColtShaft Constant uses a fixed speed fan, sized to provide the full ventilation rate when the stair door is open. To avoid over depressurisation of the lobby or corridor when the doors are closed, an adjustable door closer is provided to the stair door which can be set to allow the door to be pulled open sufficiently to maintain a set pressure difference, normally around 25Pa. To allow this, the doors opening onto the lobby or corridor should be reverse hung to be pulled open by escaping occupants rather than opening in the direction of escape as is the conventional practice.
The quest for energy efficiency has led to very good insulation in residential buildings. While this is very good for the environment and electricity bills, it is having unintended consequences stair lobbies, corridors and entrance halls, which tend to overheat.
Using the equipment specified to provide smoke control of the common areas, it is possible to provide a simple and effective cross flow ventilation system to extract warm, stale air from these spaces and their ceiling voids.
Please contact us for more information relating to the application, specification, installation and servicing of this product.