Ensuring fire system effectiveness in historic sites
30 May 2017
The threat and consequences of fire in any building are serious, but historic structures pose a particularly complex challenge for the people and systems charged with protecting them. Aston Bowles, marketing manager at Advanced explores the options.
Not only do historic buildings tend to be complex and varied in their design and construction, the contents will often include furnishings and artifacts of high monetary and historic value. Safeguarding the occupants, fabric and contents of these buildings is of paramount importance, especially where large numbers of staff and visitors are involved, such as in stately homes, museums or other historical attractions.
An in-depth fire risk assessment needs to be carried out and, in the case of historic structures, normally needs to be supplemented with a more in-depth fire safety management plan, in line with the Regulatory Reform (Fire Safety) Order 2005. The assessment should cover important factors such as active and passive protection measures (both in place and required), mitigation of identified risks, staff training, maintenance and review periods.
At the centre of any active system is the fire panel – single or multi-loop, standalone or networked. The choice available is wide, but not simple, and the installation costs are likely to dwarf equipment prices. For this reason, finding a system that is easily installed with flexible cabling and a range of communication options should be the priority. Given the complexity of the sites an analogue addressable system that provides more control and scalability is often preferred.
A vital consideration with historic sites is the extent to which they allow you to subdivide and control the fire system and its outputs before, during and after a fire condition. The fire system should offer multiple cause and effect options to accommodate the wide range of uses, room sizes, layouts, spaces and technical challenges found in such buildings.
Heritage buildings are often in remote locations with difficult access, and are more likely to be connected to Alarm Receiving Centres. If an unreliable or inappropriate system is installed, the downstream costs of fault-finding, repair and maintenance will be significant.
A recurring challenge is to make the system as unobtrusive as possible without impacting performance. Thanks to repeater panels, the larger fire panel can be hidden from view. Some new repeater panels are designed to suit many locations, to flush fit and can add new performance features such as digital zone plans and active maps showing fire status throughout a site.
Multiple factors can impact the challenges facing an active fire system, and these are often aggravated in historic structures. Irregular room geometry, large windows, archways, open fireplaces and high, suspended or decorative ceilings can create detection challenges.
The standards for detector placement are dictated by BS5839, which also gives detailed guidance on the options for different detection types in unusual spaces.
Extreme care must be taken to ensure that smoke can reach detectors, and it is also important to place detectors in such a way that smoke does not stratify beneath the detecting element or otherwise delay the efficient detection of smoke, again BS5839 will provide guidance. Different materials will dictate the likely speed and spread of fire in an old building, so detection choice and associated system programming covering the spectrum of operations from alarm confirmation and alert methods to evacuation strategies and integration with third party systems is crucial.
There are many detection methods suitable for historic structures and it’s common to find many of them on a single system. Modern analogue addressable point detectors are hugely reliable and increasingly sophisticated. The most common type is the optical smoke detector with many options available with different detection and analysis methods used. Heat detectors are common in spaces such as kitchens where steam and cooking smoke are present, and multi-sensor detectors are often used as they combine heat and smoke detection in a single unit which can be used as general detection with real advantages for signal confirmation. Many points can have sounder and strobe options added or have them ‘on-board’ the device and more exotic detection modes such as CO are coming to market and are already specified for certain uses in some standards regimes.
Floors and ceilings in older structures are often wooden, so fitting cable systems to approved standards without suspended steel trays can be a challenge. A much less invasive solution uses wireless point detectors, that also come with most of the detection and technology options of their wired counterparts.
Wireless solutions not only mean lower visual and physical impact, they are also faster and cheaper to install. Thanks to two-way communication with the panel, battery replacement and fault reporting can be worked into the on-going maintenance schedule via the panel service tools, and they are increasingly popular.In conclusion, historic structures have always presented a unique challenge for the fire system industry but innovation is delivering more choice and performance for end users, specifiers and responsible people in the sector. The choices made need to be based on a thorough understanding of the technology and standards present within the context of a particular site.