Although the recession isn’t yet a distant memory, the country’s industries are very much on the rise.
This, in turn, has led to property developers and contractors working on new commercial builds, however, there are (as with all property types) certain fire safety regulations which must be considered.
Approved Document B (ADB)
One key item to consider is Approved Document B (ADB) of the Building Regulations 2010, an advisory document which makes a number of design suggestions in order to meet the functional requirements of the Regulations. For instance, ADB calls for any office in which the top floor is more than 11m above ground level to feature two staircases in order to provide a suitable method of escape.
Similarly, ADB requires buildings with a floor located more than 18m from the access level to feature a firefighting shaft, complete with a firefighting lift, dry/wet rising main and ventilated firefighting lobby.
The most simple way of ventilating this lobby is through the use of an external 1.5m2 window which can be opened by the attending fire service to allow the extraction of smoke. Where the firefighting shaft does not feature an external wall, natural smoke shafts can be utilised, with a 3m2 shaft and accompanying 1.5m2 openings onto each of the building’s floors being required.
However, as an advisory document, ADB’s recommendations are effectively suggestions, and may not always be the most appropriate option in every scenario, especially when developers are looking to minimise costs and maximise available space. As stated in Approved Document B:
“…there is no obligation to adopt a particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way”
This alternative approach, known as an ‘engineered solution’, offers a far less restrictive plan to be put in place, taking into account a commercial property’s design, layout and occupancy levels.
By taking this approach, significant cost and space savings can be achieved, for instance, it may be possible to remove the need for a building’s secondary staircase, greatly increasing the available floorspace and in turn offering the developer more saleable space, increasing potential profits.
One such method of achieving these space-savings is the inclusion of pressurisation systems. In buildings over 11m in height, these systems are an industry-recognised method of providing means of escape, however where buildings are over 18m in height the system must be enhanced to also aid in firefighting operations, protecting the firefighting shaft from smoke ingress.
As the design requirements for pressurisation systems are outlined in BS EN 12101 Part 6, their inclusion can easily be justified through the submission of calculations which demonstrate their effectiveness.
Although the use of pressurisation systems can enable access to greater floor space than if natural systems were used, they also have relatively high initial costs and are more complicated to install and commission.
Mechanical Smoke Ventilation Systems
Alternatively, mechanical smoke ventilation systems can be utilisted. Consisting of powered fans attached to a mechanical shaft, these systems allow smoke to be extracted from the affected floor, while also preventing its movement into nearby areas, enabling the escape of occupants while improving visibility for the attending fire service.
In order to prove the effectiveness of mechanical systems, each installation must be considered on a project-by-project basis. To achieve this, fire design consultants can utilise tools such as Computational Fluid Dynamics (CFD) modelling.
By creating a virtual model which shows the movement of smoke and fire through the building, CFD can demonstrate the mechanical smoke ventilation system’s ability to remove smoke from the protected lobby, with analysis and a supporting report being submitted to the relevant building control body to justify the design.
Regulatory Reform (Fire Safety) Order 2005
One of the key pieces of legislation which must be kept in mind throughout a project is the Regulatory Reform (Fire Safety) Order 2005 (or RRO), which must be complied with following construction. Failure to do so results in enforcement action which could include a prohibition notice, potential prosecution, fines or even imprisonment for building owners and managers.
The order applies to most non-residential properties, including offices and shops, pubs, clubs and restaurants, hotels and care premises, such as hospitals and care homes. One of the key elements introduced by the RRO is the need for employers to appoint a ‘responsible person’ (usually the building’s owner or manager), who must carry out a fire-risk assessment and ensure that all reasonable steps are taken to ensure that safety is maximised.
Regardless of the approach taken, it’s vital that all fire safety system and products comply with the relevant product regulations, largely European Standard BS EN 12101, which lays out the specification for natural and powered smoke and heat exhaust ventilators. By utilising approved products, their quality can be guaranteed – provided they are installed and maintained correctly – maximising the safety of the commercial property in question.