Rob Gunningham of SE Controls discusses regulations, compliance and best practice for fire safety
Fire safety is more than ever a prominent issue within the construction industry, as a result of the high-profile failures associated with Grenfell Tower. While certain remedial measures are being addressed, there is a lack of clear guidance when it comes to regulations and compliance for smoke control systems, from specification and design through to installation and post-occupancy maintenance regimes.
Smoke control systems are among the most highly regulated aspects of a building’s design. From our experience of running regular CPD events for architects and specifiers, it is often apparent that regulations need interpreting and ‘decoding’ to help best practice emerge through a greater level of understanding. Under the UK Construction Product Regulations, products that have a harmonised European standard (hEN), must be CE certified against that standard.
The following EN 12101 series of harmonised standards apply to smoke ventilation products:
- EN12101 Part 1 Specification for smoke barriers
- EN12101 Part 2 Natural smoke and heat exhaust ventilators
- EN12101 Part 3 Specification for powered smoke and heat exhaust ventilators
- EN12101 Part 8 Smoke control dampers
- EN12101 Part 10 Power supplies.
Windows automated for smoke ventilation fall into the smoke and heat exhaust ventilator (SHEV) standard EN12101-2.
EN 12101-2 dictates that actuators and vent profiles must be tested together as a single system, at an accredited facility, to all annexes of the prescriptive standard. There are also strict audited procedures to fabricate and install the components, to ensure they are manufactured as tested. Failure to follow this procedure means that the required Declaration of Performance (DoP) certificate cannot be issued, therefore the solution is not compliant.
Compliance & diligence in design
In addition to component regulations, the most important design and specification reference is Building Regulations Approved Document B (ADB). This not only provides all the necessary guidance on escape travel distances and smoke control options, but also gives details on the location of vents, free area calculations and other key considerations, yet it must be remembered that ADB is a guidance document and shows minimum compliance standards for fire safety in occupied buildings.
However, unless the specifier is fully conversant with every aspect of ADB, there is potential for the specifications to be misinterpreted. For example, Section 2.26 requires smoke vents to be located either on an external wall or discharge into a vertical smoke shaft, yet each option also has additional specification criteria which have an impact on the building design.
When located on an external wall the smoke vent’s minimum free area to enable smoke to escape is 1.5 m2. However, as the free area is dependent on the window size and the amount it opens, this has a direct influence on window sizing. Also, the free area requirement calculations must be undertaken in accordance with ADB Appendix C – ‘Methods of measurement’, or alternatively the aerodynamic free area can be declared, which satisfies BS EN12101-2:2003 for natural ventilators.
ADB also demands that a smoke shaft opening at roof level must be at least 0.5 m above any surrounding structures within a horizontal distance of 2.0 m and extend at least 2.5 m above the ceiling of the highest storey served by the shaft. This has clear implications for the building design, such lift shaft over-runs and parapet walls, which affects the location of smoke shafts and the location of roof mounted plant.
The key point for specifiers to take from these examples is that there are several areas where the regulations may be open to misinterpretation and the design could be compromised, as an unintentional consequence.
With the release of BS7346 Part 8 ‘Code of practice for planning, design, installation, commissioning and maintenance’ in 2014, navigating the compliance issues surrounding all aspects of smoke control systems was made simpler and more integrated.
This standard goes beyond the design stage to incorporate guidance and best practice on installation and commissioning as well as planned ongoing maintenance. Maintenance is a key feature of life safety systems, such as smoke control, as even the best designed solutions can be compromised or even fail, if they are not maintained in accordance with the regimes specified by the manufacturers.
It also adds further elements that need to be considered by architects and other disciplines involved in the design process. The standard deals with ‘cause and effect’ – key principles of effective smoke control system design, operation and safety.
Consulting engineers, architects, design teams and installers will already be familiar with the principles of cause and effect, but BS7346-8 makes it a discrete but inherent part of the overall system process to ensure failsafe operation and system integrity.
As smoke control systems are essential for the protection of life, it’s arguable that smoke control specialists should be included in the building design at a very early stage.
This can help smooth the overall design process and help avoid issues later in the construction process where some aspect of the complex regulation matrix might have been overlooked, such as the example of roof mounted plant and walls.
While the regulatory framework is complex, demanding and in some cases confusing, they exist to protect building occupants, and there is an obligation to ensure the building design and life safety systems integrate as a complete solution, built on compliance and best practice.
Rob Gunningham is director of SE Controls