Hard though it is to credit, some architects think smoke detectors are actually unsightly, and that fire safety systems should only be heard in an emergency, but not seen. Marek Jaros looks at the options there are to balance safety with aesthetics in heritage buildings and contemporary designs alike.
We know that the safety of people and property is of paramount importance, but in modern designed or heritage buildings, the need for prompt fire detection often conflicts with the aesthetic and design requirements of architects and conservationists. But there are ways to satisfy these needs, while guaranteeing early fire detection.
I will contrast traditional methods of fire and smoke detection with new approaches to the problems. Traditional methods include:
– Point smoke detectors (flush installation, telescopic pole)
– Aspirating smoke detectors
– Reflective beam smoke detectors
– Flame detectors
– Manual call points (flush installation)
Through my own experience, I have come across many ways to make point detectors ‘invisible’. The first method is to cut an opening in the ceiling, install a detector in the space and cover it with protective grating. When the grating is painted the same colour as the surrounding ceiling, it almost disappears. This solution was successfully implemented, for example, in the Chateau Vranov nad Dyji in the Czech Republic.
Mobile coverage
A second solution was used in a bank in Prague’s old town. In the case of historical buildings in the Czech Republic, final building approval includes a certificate from the Monument Preservation Office as well as a fire safety certificate. At the bank, the conservationists did not allow any alterations of the ceiling, while the fire safety officer insisted on a point detector below the ceiling. In the end, a solution was found where during the day, any alarm needs to be activated manually by staff. Outside working hours, however, a telescopic pole elevates a smoke detector mounted on a wooden board to a point close to the ceiling.
A third possible solution is aspirating smoke detection. The main components of this are an aspirating unit, which can be placed outside the protected room with pipes running above the ceiling. Connected to the pipes are capillary tubes which lead to almost invisible external sampling points. The historical room is protected by a pipe in the double ceiling, while the entrance hall and reception area are protected by a pipe in the lower ceiling.
In some cases, the use of a reflective beam detection is an architecturally more acceptable solution. Such detectors have a transmitter and a receiver integrated into one unit, which is placed on one side of a room with a reflective prism on the opposite side. The prism functions as a small mirror that reflects the beam back to the receiver. Properly positioned, the detector is invisible from public view.
Flame detectors are yet another solution. In this case, detectors have a similar coverage area to that of PIR detectors used in intrusion alarm systems. Rather than being installed on a ceiling, a flame detector can be installed less obtrusively on a wall or in a corner. In order to help designers even more, the cover (not the sensor) can be painted the same colour as the wall to blend in with the surrounding area.
New solutions
Over the last few years, however, a new solution for interiors with high aesthetic requirements has emerged – an optical smoke detector with a ‘virtual’ optical chamber. This solution is new because the optical part of the detector is outside the detector housing itself. The principle is demonstrated in the diagrams: the optical sensor (1) contains an LED (2) and a photodiode (3). The optical sensor and a scattered light area (7) create the ‘virtual’ optical chamber. When smoke appears in the area (7), the reflected light lands on the photodiode (3). The received signal is analysed by digital processing algorithms and is compared to reference data – if the comparison is positive an alarm is triggered.
But what about other light sources, dust or insects? The detector is equipped with optical and electronic filters able to eliminate these light sources. Dust generally tends to settle on uneven surfaces and the topside of objects, but the active part of the detector is on the lower side and this side is flat and smooth, so dry dust just can’t settle there.
Insects can influence the detector if they are in the area for several seconds, but such behaviour is not typical of crawling or flying insects. For these reasons, the technology is as reliable just as conventional point detectors from the point of fast fire detection and resilience to false alarms.
Due to the inventive design, maintenance is more straightforward than ‘visible’ detectors. The presence of an impurity layer, such as greasy dust on the detector surface, is detected by a contamination sensor (6). When a certain threshold is exceeded, the contamination will be signaled and the surface needs to be wiped. Coloured rings can be inserted on the detectors so that they blend in with the surroundings. These detectors are suitable alternatives for entrance ways, historical and other architecturally challenging areas. Detectors such as these are available from Bosch, and are being developed by Apollo for launch in Spring 2008.
As can be seen from all of the above, there is an increasing number of options for architects and designers to satisfy the requirements of heritage building authorities and general aesthetic consideration, while providing the detection requirements of the 21st Century.
Marek Jaros is senior fire engineer at Euroalarm, a leading distributor and systems integrator in the Czech Republic. The company works with some 50 fire and security manufacturers from around the world.
Hard though it is to credit, some architects think smoke detectors are actually unsightly, and that fire safety systems should only be heard in an emergency, but not seen. Marek Jaros looks at the options there are to balance safety with aesthetics in heritage buildings and contemporary designs alike.
We know that the safety of people and property is of paramount importance, but in modern designed or heritage buildings, the need for prompt fire detection often conflicts with the aesthetic and design requirements of architects and conservationists. But there are ways to satisfy these needs, while guaranteeing early fire detection.
I will contrast traditional methods of fire and smoke detection with new approaches to the problems. Traditional methods include:
• Point smoke detectors (flush installation, telescopic pole)
• Aspirating smoke detectors
• Reflective beam smoke detectors
• Flame detectors
• Manual call points (flush installation)
Through my own experience, I have come across many ways to make point detectors ‘invisible’. The first method is to cut an opening in the ceiling, install a detector in the space and cover it with protective grating. When the grating is painted the same colour as the surrounding ceiling, it almost disappears. This solution was successfully implemented, for example, in the Chateau Vranov nad Dyji in the Czech Republic.
Mobile coverage
A second solution was used in a bank in Prague’s old town. In the case of historical buildings in the Czech Republic, final building approval includes a certificate from the Monument Preservation Office as well as a fire safety certificate. At the bank, the conservationists did not allow any alterations of the ceiling, while the fire safety officer insisted on a point detector below the ceiling. In the end, a solution was found where during the day, any alarm needs to be activated manually by staff. Outside working hours, however, a telescopic pole elevates a smoke detector mounted on a wooden board to a point close to the ceiling.
A third possible solution is aspirating smoke detection. The main components of this are an aspirating unit, which can be placed outside the protected room with pipes running above the ceiling. Connected to the pipes are capillary tubes which lead to almost invisible external sampling points. The historical room is protected by a pipe in the double ceiling, while the entrance hall and reception area are protected by a pipe in the lower ceiling.
In some cases, the use of a reflective beam detection is an architecturally more acceptable solution. Such detectors have a transmitter and a receiver integrated into one unit, which is placed on one side of a room with a reflective prism on the opposite side. The prism functions as a small mirror that reflects the beam back to the receiver. Properly positioned, the detector is invisible from public view.
Flame detectors are yet another solution. In this case, detectors have a similar coverage area to that of PIR detectors used in intrusion alarm systems. Rather than being installed on a ceiling, a flame detector can be installed less obtrusively on a wall or in a corner. In order to help designers even more, the cover (not the sensor) can be painted the same colour as the wall to blend in with the surrounding area.
New solutions
Over the last few years, however, a new solution for interiors with high aesthetic requirements has emerged – an optical smoke detector with a ‘virtual’ optical chamber. This solution is new because the optical part of the detector is outside the detector housing itself. The principle is demonstrated in the diagrams: the optical sensor (1) contains an LED (2) and a photodiode (3). The optical sensor and a scattered light area (7) create the ‘virtual’ optical chamber. When smoke appears in the area (7), the reflected light lands on the photodiode (3). The received signal is analysed by digital processing algorithms and is compared to reference data – if the comparison is positive an alarm is triggered.
But what about other light sources, dust or insects? The detector is equipped with optical and electronic filters able to eliminate these light sources. Dust generally tends to settle on uneven surfaces and the topside of objects, but the active part of the detector is on the lower side and this side is flat and smooth, so dry dust just can’t settle there.
Insects can influence the detector if they are in the area for several seconds, but such behaviour is not typical of crawling or flying insects. For these reasons, the technology is as reliable just as conventional point detectors from the point of fast fire detection and resilience to false alarms.
Due to the inventive design, maintenance is more straightforward than ‘visible’ detectors. The presence of an impurity layer, such as greasy dust on the detector surface, is detected by a contamination sensor (6). When a certain threshold is exceeded, the contamination will be signaled and the surface needs to be wiped. Coloured rings can be inserted on the detectors so that they blend in with the surroundings. These detectors are suitable alternatives for entrance ways, historical and other architecturally challenging areas. Detectors such as these are available from Bosch, and are being developed by Apollo for launch in Spring 2008.
As can be seen from all of the above, there is an increasing number of options for architects and designers to satisfy the requirements of heritage building authorities and general aesthetic consideration, while providing the detection requirements of the 21st Century.
Marek Jaros is senior fire engineer at Euroalarm, a leading distributor and systems integrator in the Czech Republic. The company works with some 50 fire and security manufacturers from around the world.
