Issue 40 winter 23 web - Flipbook - Page 68
Fire alarm installations
in heritage buildings
by Geraldine O’Farrell CEng FCIBSE FIET FSLL
Geraldine is a Senior Building Services Engineer with Historic England, and before that its predecessor
English Heritage, for the last 25 years. She is the author of Historic England’s guidance on Fire alarms,
Internal and external lighting, Daylight harvesting, Surge and Lightning protection and has given
webinars on all these topics, recordings of which can be found on the HE website under “Technical
Tuesdays”.
Fire is probably the most destructive event that can
happen to any building. Damage is not only caused by the
heat and smoke but also the impact the water used to
extinguish it can cause. Therefore, protection against and
early warning of fire are two of the most important issues
to consider regarding services to be installed within any
building.
As well as the concerns with historic construction
methods there is the issue of ensuring that an automatic
fire detection system is sensitively installed so that is not
visually intrusive and in the case of large heritage buildings
such as cathedrals and churches, capable of detecting
smoke or flame within such large interior spaces which
can often prove challenging.
Historic structures pose more of a problem by virtue
of the way some of them have been incrementally
constructed, altered and added to over long periods of
time. This can often produce hidden voids and routes
through which a fire can spread unseen and undetected.
There is also the unknown fire load, the lack of
compartmentalisation and the associated problems with
introducing any sort of passive fire measures such as fire
doors
Automatic fire alarm systems developed as early as the
19th century in America and in the early 20th century
both the heat and smoke detector were discovered both
by happy accidents but were not fully developed into the
devices we know today until the 1940-50’s.
Modern fire alarm systems are covered by several
guidance and regulatory documents including British
Standard BS 5839 which defines eight individual fire
categories, with each category falling under three different
type of system, manual (M), life protection (L) and
property protection (P).
Unfortunately fire not only occurs by accident but by
arson attacks so it is important that any protection system
gives as early a warning of fire to the owners, custodians
and local fire services as possible.
Above, an old fire alarm sounder at Otter Mill, Ottery St Mary
(Listed Grade II) © Historic England Archive
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