Providing effective fire detection for high value property, modern residential and commercial, is a challenge. The voluminous spaces and aesthetic considerations are a couple of key issues that must be considered when choosing and installing effective fire detection solutions.
The amazing creativity of modern building designs, being or have been built in considerable numbers, present a new set of challenges for fire detection solutions.
The Gherkin, a building we help protect, is just one example of a property with a completely original and unique design. In 2006, when it was last sold its value was £595,000,000.
Commercial properties such as The Gherkin, competing for tenants, need to not only ensure their safety but also project a faultless image for their clients, which are using the status of the properties to attract business and enhance their own brand.
There can be no compromise on the reputation of the building and this very much includes eliminating the risk of fire.
Only recently a newer addition to the London skyline, The Shard, was the subject of national media coverage when smoke was seen billowing from its basement. Luckily, it proved to be a false alarm, but the potential for serious damage to its reputation and commercial viability was clearly highlighted.
Modern buildings generally don’t have the same regulatory considerations as heritage buildings.
Nevertheless detection points and surveillance monitoring equipment are often expected to be unobtrusive, not unduly affecting the design.
In the case of The Gherkin, cameras were placed at the top of 25m light wells (described below) ensuring they were very discreet while well placed for effective fire detection surveillance.
In many instances there are numerous opportunities for detectors, such as cameras, to be hidden: above the ceiling with a cut out for the camera lens, above exposed girders and even concealed in certain types of lighting fittings.
Many projects require creativity to find a solution that provides a place for detectors without being obtrusive.
The voluminous, often unusual, spaces created by new designs can be problematic.
Let’s take The Gherkin again as a modern example.
The lobby of this iconic property reaches 6.5 metres and has 6 light wells with a depth of 25m, which are used for ventilation.
Such spaces can be challenging for fire detection.
Smoke stratification means that systems that rely on detectors being activated by smoke particles reaching sensors can be compromised.
Heated by the fire, smoke rises. When the smoke cools and comes down to the temperature of the surrounding air, it stratifies – an effect known as The Equilibrium Point.
Systems that are reliant on smoke particles reaching detection points cannot guarantee that stratification will not happen before it rises to trigger the alert. In addition, air flow behaviour can vary greatly, leading to complex and sometimes unpredictable smoke behaviour.
Smoke also takes time to reach point detectors. Indeed, it may never reach them in extreme circumstances.
Any effective solution has to factor this in to protect the high value assets of their owners.
Advanced fire detection solutions to consider
The main fire detection solutions for high value properties are Visual Smoke Detection (VSD), Infrared (IR) and Aspirating smoke detectors (ASD).
Each fire detection system offers its particular strengths for the specific requirements of each building: sensitivity to aesthetic demands, scope for creativity and effectiveness to the particular challenge at hand.
Let’s have a look at the principal solutions:
VSD offers high value property buildings a system that can detect fire at source, without sensors having to be triggered. Using visual monitoring, large voluminous areas can be surveyed and can be focused on areas of particular concern if required. The complexities and challenges of smoke stratification are effectively removed.
The system works by detecting smoke patterns as well as changes in brightness, contrast, shape, motion, colour matching, content and loss that could indicate the early stages of a fire. Visual verification, on or off site, can determine if the situation warrants further action.
Infra Red has many of the properties of VSD, especially in relation to voluminous areas and not relying on smoke to reach detectors, although it cannot be used for visual verification and footage is not provided for analysing situations to improve safety.
Aspirating Smoke Detection is excellent in clean environments. It works by drawing air through into a central detection unit from a network of pipes. The sampling chamber detects the presence of smoke particles suspended in air by noting the light scattered by them in the photoelectric chamber.
ASD is popular but does have drawbacks for certain sites. The main ones being its difficulty in differentiating between smoke and dust, and if pipes have to be placed high up then smoke stratification can compromise the system.
The key to a successful solution is not centred on compromise, but on a creative approach balanced with the most effective fire detection solution for the building in question. Each system offers benefits that can be considered in how best to protect the building. Today’s systems offer a range of solutions that can be considered to protect effectively high value property.
This article was featured in December’s Building Engineer magazine