Protecting our past
09 February 2017
Warren Moyle and Bill Jordan explore how fire detection systems are protecting heritage sites housing our national treasures, and historic townhouses that are home to multi-million-pound apartments across the UK
PROTECTING HERITAGE properties is a complex challenge that requires numerous factors to be considered. Life safety should clearly always be paramount in any system specification, but it’s a sad fact that any fire occurring in a historic building will most likely result in the loss of priceless and irreplaceable contents, and run the risk of structural damage and loss of architectural features.
As well as the usual need for early warning, designers of fire detection systems for heritage properties must consider the need to avoid false alarms, particularly as many heritage buildings are either tourist attractions, which enjoy a high number of visitors, or flat conversions that house multiple residents.
Historic buildings are, by definition, old and thus were constructed at a time when there were few, if any, building or safety standards. Although most of them were originally built as homes, historic buildings are now used for various purposes. Many of them now house a lot of modern equipment, such as computer systems, generators and catering facilities.
This affects the type of fire detection systems that need to be installed and also requires fire safety specialists to ensure that an effective fire evacuation strategy is in place.
Maintenance is another consideration. Heritage buildings undergo regular preservation and repair works, which involve risks that need to be factored into the design of a fire detection system. Hot works, such as welding and soldering, present a major fire risk, particularly when carried out around combustible materials, such as wooden beams, thatch, and old furnishings.
Another less critical, but still significant, issue is that of aesthetics, especially in buildings where historical and archaeological integrity have been preserved. In such cases, it is important to balance the fire protection needs of a site and ensuring compliance with insurance companies and/or building-authority standards with the need to make its detection systems as unobtrusive as possible.
One of the most popular ways of achieving this is by placing the system’s most obvious elements within specially designed housings. As an example, Firetecnics recently worked on an old manor house, where the owner wanted the sounders in the library to be as inconspicuous as possible. The sounders were positioned within hollowed-out, matching, leather-covered books and so completely blended in with their surroundings.
Another client, who owns a property near Harrods, in London, commissioned a pair of walnut cabinets to be built – one to house his control panel and the other for his own use. The visual impact of the two together is impressive. We’re currently exploring a similar option for a historic church, where the fire brigade has ruled that the control panel must be positioned within the entrance, but doing so would spoil the look of this lovely old building.
Where logistics and budgets don’t allow for total concealment, there are many clever ways of making fire detection as discreet as possible. It’s an established fact that the human eye is automatically drawn to the centre of a room, so by positioning elements in the corners of a room, rather than the middle, the visual impact is less noticeable. We also use techniques such as placing detectors above top picture rails, lining them up in even numbers alongside plaster detailing, and positioning sounders behind the thick curtains that are often found in heritage properties. While this does mean more sounders are needed to do the job effectively, this cost can be justified by the aesthetic gain.
It is important to remain flexible and adopt a common-sense approach to historic properties, while still meeting fire regulations. One of our projects involved an old building, which had been converted into flats and had a beautiful 200-year-old wooden door. Ideally, this would have been a fire door but the owner of the building was obviously very keen to keep the existing door. So we used the very simple solution of placing a detector directly on either side of the door to maximise fire and smoke detection in its vicinity.
Manual call points (MCP) are probably the most challenging aspect as, by their nature, they are the one element of a detection system that needs to be visible. Even in a converted house where residents are aware of what they need to do in an emergency, visitors to the building may also need to know how to activate an alarm system. In historic buildings that are open to public visitors, this visibility is even more crucial. While we can’t hide an MCP, it is certainly possible to blend it into its surroundings. Examples of this include mounting them on material that matches other aesthetic detailing in the property, such as brass plates, or even making a framed surround to lessen the contrast between the wall and the MCP.
Although the approach to fire detection in historic buildings needs to be tailored to fit a range of specific criteria, the most popular product type Apollo specifies for such applications is a multisensor range, such as the SOTERIA collection, which can be programmed to switch smoke sensors over to heat sensors at different times of the day.
The range uses new optical sensing technology, PureLight®, to detect smoke particles entering its chambers. This unique system marks a new stage in the development of advanced optical technology, which increases the reliability of fire detection while resulting in fewer false alarms, making it ideal for the challenges often presented by heritage properties.
Numerous other technical developments have been integrated into the SOTERIA design, including an advanced-technology chip sensor to improve smoke detection, and a sleek, low-profile design, which means less dust penetrates the outer casing. We have also designed the detectors to be less sensitive to any dust that does accumulate over long periods of time.
We have worked quite closely with English Heritage in the past. Many of its sites are remote and in countryside settings, making them susceptible to insects. Bug screens inside detectors have been successful in keeping insects out of the optical chamber. Careful design of this chamber also ensures that any insect small enough to penetrate the mesh barrier has fewer opportunities to interrupt the operation of the smoke detector.
Wireless detectors are a great way of providing effective fire detection without a tangle of visible wires and cables in architecturally-sensitive buildings. They also avoid the need for invasive drilling. An example of this can be seen in Exeter Cathedral. One of the finest examples of Gothic architecture in the country, it features the longest uninterrupted stretch of decorated vaulting in the world. Heritage Lottery Funding was secured to transform the upper floor of the cloisters into a dedicated space providing modern learning facilities, while retaining the historic legacy of the building. As part of this programme of work, XPander was installed to provide fire detection without compromising the aesthetics of the ceiling.
From a manufacturer’s point of view, we need to ensure that our detection systems do not stand out like a sore thumb. On the installation and design sides, we must strive to provide clever solutions to conceal and minimise a detection system’s visibility. It’s common to hold four or five site meetings with property owners, management companies and guardians before we even put pen to paper to provide designs and costings.
Each historic building is unique, and while we can’t advise on a one-size-fits-all system, our many years of experience have shown that the best approach is often to opt for either the reliability and flexibility of a multisensor system, the discreet option of a wireless solution, or, indeed, a combination of the two. By working closely together, Apollo and Firetecnics can continue to ensure effective fire detection, while remaining sympathetic to a building’s aesthetic and historical integrity.
Warren Moyle is senior product support engineer at Apollo Fire Detectors and Bill Jordan is quality manager at Firetecnics Systems