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How can rooflights support a commercial buildings’ fire strategy in line with Part B of the Building Regulations?

The design of commercial buildings has become increasingly progressive as architects ‘push the boundaries’ to create more dynamic spaces. Often the layout to these buildings may not conform to “the norm”, the materials used may be new and progressive, and complex building management systems may be involved.


The installation of rooflights and skylights in all manner of commercial spaces has increased dramatically in recent years, as we seek to maximise daylighting spaces, and enhance the wellbeing and productivity of building occupants.


Operating as part of a natural smoke and heat exhaust ventilator system (NSHEV), Automatic Opening Ventilators (AOVs) within a rooflight scheme can also be instrumental in providing fresh air and dissipating heat, reducing the risk of solar overheat where a building uses a lot of glazing and is also highly insulated. AOVs can also provide critical smoke ventilation. Indeed, smoke control using natural ventilation through operable rooflights is an especially effective means of protecting escaping occupants, those awaiting rescue and fire-fighters from the immediate dangers of fire and smoke.


What is the purpose of a Fire Strategy and how does it relate to Approved Document Part B Vol 2? 

BS PAS 911 refers to a Fire Strategy as providing ‘a clear set of measures encompassing fire precautions, management of fire safety and fire protection’. It involves the development and implementation of risk appropriate policies and procedures in line with objectives specific to the business. Its aim is to reduce life risk while protecting business procedures and assets. It will identify the extent of fire protection required throughout the building.


Building Regulations 2010 provides the mandatory framework for any fire strategy, whilst Approved Document B Vol 2 (flats and non-dwellings) 2019 edition provides guidance on how to meet the requirements with respect to fire safety. Similar requirements are to be found in:


Section 2 of the Scottish Buildings Standards Agency Technical Handbooks 2007

Technical Booklet E of the Building Regulations (Northern Ireland)

Technical Guidance Document B of the Government of Ireland Building Regulations 2006


Smoke control central to a fire-engineered solution

The control of fire and smoke is a sub-strategy listed in BS PAS 911 – smoke control is defined as an “active protection” strategy. The formulation of an efficient and safe smoke ventilation system requires specialist expertise, usually involving a building engineer, and mechanical and electrical consultants. Their assessment report will detail what kind of fire strategy is needed and how much ventilation is required. The choice of smoke and heat control methods for a building, whether natural or mechanical, or even a hybrid type solution, is determined after establishing the routes fire and smoke would take in such an event. Central to any fire strategy is the need to minimise the conditions that might cause potential “flashover”, which can be deadly. A lack of smoke and heat ventilation in a room/building increases the risk of heat radiating from the ceiling, which can then ignite air-borne gases causing a potential flashover.

The role of rooflight AOVs in commercial buildings as part of a smoke and ventilation strategy

Approved Document B Vol 2 identifies several situations where the use of AOVs to provide natural ventilation is appropriate. Reducing the number of possible penetrations on a roof, however, by using rooflight systems to multi-task, in other words to provide daylight, access (for maintenance) as well as smoke ventilation is key to modern building design.


In Appendix D of Approved Document B Vol 2 there is reference to BS EN 12101-2:2003, which is critical in the designing of ventilation strategies in commercial buildings, and for the testing of AOVs including smoke-venting, openable rooflights.

BS EN 12101-2:2003

This harmonised standard specifically applies to natural smoke and heat exhaust ventilators operating as part of smoke and heat exhaust systems. It stipulates the requirements and the rigorous performance test methods for them if they are intended to be used in a building’s smoke and heat control system. BS EN 12101-2:2003 is the only standard that certifies the compliance of a smoke ventilation system.


It is the responsibility of the architect or fire officer to approve the installation of the correct AOV roof light, which must not only comply with Building Regulations but also have passed the tests, which adhere to BS EN 12101-2:2003. The AOV rooflight must have a CE mark and a Certificate of Conformity supplied by a UKAS accredited body must be provided by the manufacturer of the AOV system.


There are 8 sections within BS EN 12101-2:2003 relating to testing, and test regimes can vary between manufacturers of rooflights. Xtralite offers a depth of expertise in compliance with BS EN 12101-2:2003, and the company’s rooflights, and glazing, are tested to the highest level of repetitions as laid out in the standard’s test criteria.


Choosing the right rooflight AOV solution

Natural ventilation is provided through either high-level smoke outlet vents and low-level fresh air vents which open automatically via actuators when there is a fire, allowing cool air into the building and hot air and smoke to flow out. A smoke-free layer is thereby created, which improves the conditions for occupants to escape and for fire-fighters to enter.


Various AOV options are available, from modular domes through to structural glazing systems with integral AOV sections. Vents can be in the form of single units, which open to 140 degrees, or a type of louvre construction. A simple AOV system is typically used over a stairwell in a building, but both networked and centralised control systems offer greater flexibility and integration into a building’s management system.


A networked system is ideal where wiring distances are quite long or where there is not so much space for a central zoned control panel. The advantage to a centralised control system, on the other hand, is that primary and secondary power for the system can be located on one control panel.


Where there is a requirement to integrate openable rooflights, and AOVs, into a Building Management system this needs to be clarified at the design stage with the involvement of the rooflight manufacturer as retro-fitting to an existing BMS, particularly one that is quite complicated, is not always achievable.


Safety has been at the forefront of Xtralite innovation and we have developed a comprehensive range of options for rooflight ventilation and automated systems to support a commercial buildings smoke evacuation strategy. We also offer solid lid rooflights and access hatches to enable planned or emergency maintenance and access, without compromising building security.

We have developed a range of smoke ventilation AOV rooflights to specifically mimic the Xtralite standard range of modular rooflights. This gives specifiers the opportunity to maintain the external aesthetics of the building by having rooflights and smoke vent to AOVs supplied from a single source.

For more information on how Xtralite can support you in the formulation of smoke and ventilation strategies visit our product page or contact the Xtralite technical team to discuss your project requirements in line with Part B regulation.

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