Most deaths and injuries in non-domestic buildings are caused by the effects of smoke being inhaled or obscuring escape routes. Here Mark Thomson examines how sound technology can guide people out of buidings, no matter how poor the visibility.
When defining evacuation requirements, fire engineers assess the required safe escape time (RSET) against the available safe escape time (ASET), as laid out in BS PD 7972-6: 2004. While the available escape time may be difficult or costly to improve, it may be more effective to focus on reducing the required safe escape time by exploring new methods of reducing recognition, response and travel times.
Two key factors that will reduce a building’s evacuation time are persuading people to make efficient use of all available exits and reducing the queuing time at each exit. A system that can intuitively draw people towards the nearest emergency exit may optimise its use, allow travel distances to be safely extended, and enable more effective use to be made of the building.
In the great majority of commercial and industrial premises, the building’s fire alarm system is the most likely initiator of a warning about a potential threat to the occupants, although unfortunately security alerts are becoming more common. The typical audible/visual warning generated by the system obviously alerts the occupants to the fact that there is an emergency and that they should relocate or evacuate. But this does not provide any help or guidance on the optimum escape route. The reinforcement of audible/visual alarms with voice messages can help, but the effectiveness of any generalised warning system is heavily dependent on the type of premises. For example, at one end of the spectrum consider an offshore oil rig, where everyone present is very well aware of – and is trained to react to – the three main audible warnings, each with dedicated tones for: evacuate the facility; toxic gas; or fire. Contrast this situation with, say, any large public building such as a hotel, airport, shopping mall or concert arena, in which the majority of those present will be totally unfamiliar with the layout of the premises and the format of any warning signals. Research shows that there is often a considerable delay, caused by uncertainty and the fear of looking foolish, before crowds respond to a genuine warning signal. In buildings with frequent broadcasts of advertising messages or other high levels of general noise, the problem is magnified because people tune out background announcements.
No way out?
Traditionally the maps, markings and signage required by the appropriate codes of practice provide the occupants with a visible means for locating a path to safety. Exit signage is usually the primary means for locating an exit, supported by emergency evacuation plans and diagrams showing the locations of, and routes to, the exits. While emergency lighting provides restricted illumination in the event of a power failure, it will be inadequate once the exit routes are filled with smoke. Even if the power supply is not disrupted, the presence of even small quantities of smoke can cause dramatic reductions in the ability to see. Additionally in many shopping centres, there are so many notice boards, advertising displays and other visual clutter that the emergency exit signage is often overwhelmed. Many other public building have layouts where each floor is visually indistinguishable.
In an emergency, people – particularly in a crowd – do not behave rationally. The noise, confusion, concern for one’s family and fear of the unusual situation will all reinforce the primitive ‘fight or flight’ reaction. Normally, the instinctive reaction is to get out as fast as possible but as in the normal course of events people do not take note of where they are in the building, they will have no idea where to go in the event of an emergency. If people are unable to identify the nearest emergency exit, there is a strong tendency to retrace the route by which they entered the building, which will very often not be the most efficient exit route. Using the most familiar exit may also lead to crowding at the main entrance/exit while other viable escape routes are underutilised. Panic is more likely to set in if an exit route is not immediately apparent, particularly if the building is crowded and the danger is perceived to be severe and immediate.
To address the issues of effective premises evacuation, a new directional sound technology, which instinctively attracts people towards its source, has been developed at Leeds University and is now becoming available through commercial partners. The units generate broadband white noise, which is similar to many sounds found in nature to which humans instinctively respond (for example, running water or rustling bushes). This type of sound intuitively attracts the listener’s attention and draws them towards the source. The white noise, with an amplitude of at least 10dBA above the ambient background level, will cut through the hubbub and be clearly audible. In tests, conducted in pitch darkness in premises where, because of the location of the building in the side of a hill, the nearest escape route involved ascending stairs from the first floor – a somewhat counter-intuitive action – there were no problems in following the aural guidance and exiting the premises in a very short space of time by the shortest possible route.
The principle is that sound pressure waves arrive at the listener’s ears with slight differences in timing and volume depending on the frequency, relative position and distance of the source. The human brain interprets the electrical signals from both ears to give an accurate location for the source: above or below, in front or behind, near or far. As an additional benefit, as sound can travel around corners, no direct line of sight is required.
Smooth exit
In a typical application directional sounders are located at key points in the exit routes. Triggered by the fire alarm control panel, the directional sounder draws attention to exits and egress routes. The varying tones and intensities coming from directional sound devices offer easy-to-understand cues for rapidly finding exits. As soon as people hear the devices, they intuitively take notice of them to find the nearest available exit, thereby reducing exit flow time. In addition to the directional broadband output, different combinations of duty cycles, and rising or falling tones intuitively guide people up or down stairs.
The technology has a number of advantages. In 2005, over 50 people were killed and around 1500 injured in UK non-domestic buildings. The majority of those injured suffer from the effects of smoke or gas inhalation, the severity of which is normally directly proportional to the time of exposure. In addition to increased safety, the use of directional sound is particularly applicable for installations where the building owner would benefit from a performance-based approach to fire safety. Potential reduced evacuation time may allow the internal layout of the building to be configured for higher occupancy levels, or with longer emergency exit paths. By incorporating directional sound in the early stages of building design, there may also be opportunities to reduce the need for other fire and emergency systems, or to reduce risk and insurance costs in buildings or installations fitted with the technology. There may also be the opportunity to improve the use of available space, potentially giving the building owner the opportunity to improve the yield on the property. The relatively low cost of installing the directional sound technology could therefore also have an economic advantage over the lifetime of the building.
Standards covering the technology are starting to emerge: in the UK, BS 8456:2005 Code of Practice for design and installation of directional sounder evacuation systems has been published and a Publicly Available Specification, PAS41: 2003 covering performance requirements and methods of testing for directional sounders, has been published by British Standards Institution. At a meeting of a CEN/TC 72 task group considering evacuation issues, held in London in September 2006, a presentation was made giving information about a directional sounder system used to assist in the evacuation of buildings. Currently a BSI technical sub committee is reviewing PAS 41 and considering whether or not to propose it be developed to become an
EN Standard.
Mark Thomson is business development manager at KAC, a Honeywell company. The company markets the directional sound technology under the ExitPoint brand.
A LONG AND WINDING ROAD
When Oregon State University refurbished one of its halls of residence, the authorities were concerned that conventional escape route provision would not be sufficient for what is a complex building to navigate. In particular, the wings of the seven storey building are winding in nature, so corridors are curved and escape routes are not intuitive. By improving the ability to find exit routes using directional sounders, the university was able to make more effective use of student living quarters and improve safety.
Most of the university’s halls of residence are simply designed; for example, a student turns left or right out of their room, and then walks straight ahead to the stairwell at the end of the corridor. The GEM building, however, is more complicated. It is a seven-story, 120,000 square foot concrete building that was recently converted from a hall of residence with bed-sitting rooms to studio-style suites and one, two and three bedroom apartments. The food service area was also converted into loft units; altogether, 231 units were created. Each floor now consists of three wings and a central lobby with elevators. The wings are winding, so going around one corner does not necessarily bring you to a stairwell or exit.
Kurt Haapala, an associate with the buildings designers, Mahlum Architects, explains: “From the architect’s perspective, we normally try to meet the letter of the code when thinking about fire and life safety, as well as safety egress. However, when we walked through this building we were all left with a certain level of uneasiness about the egress route. It was particularly confusing to find the mezzanine level and not to know how to get in or out during an emergency.”
ExitPoint incorporates sounders, positioned at perimeter exits and stairwells, to guide building occupants to the nearest exit quickly and efficiently in the event of a fire. Triggered by the fire alarm control panel, it uses broadband sound that evacuees intuitively follow to safety. Unlike standard fire alarm sounders, which simply alert people that there is a fire in the building, directional sound technology directs occupants which way to go – an ideal solution for the halls of residence. The installation at Oregon State makes it the first university in the US to use ExitPoint in a residence hall.
Fire prevention and protection specialist Steve Owens, who witnessed a demonstration of ExitPoint, urged his colleagues to test the technology in the GEM building. “Seeing the demonstration was really the turning point for me,” he says. “We were able to utilise an area in the GEM building, bring the light level down to where it was virtually dark, add smoke and run through an evacuation scenario. It was extremely convincing. It became apparent to me that in a very short period of time, even someone unfamiliar with the building could find their way out, unassisted. I don’t know of any other system that could make that claim.”
Most deaths and injuries in non-domestic buildings are caused by the effects of smoke being inhaled or obscuring escape routes. Here Mark Thomson examines how sound technology can guide people out of buidings, no matter how poor the visibility.
When defining evacuation requirements, fire engineers assess the required safe escape time (RSET) against the available safe escape time (ASET), as laid out in BS PD 7972-6: 2004. While the available escape time may be difficult or costly to improve, it may be more effective to focus on reducing the required safe escape time by exploring new methods of reducing recognition, response and travel times.
Two key factors that will reduce a building’s evacuation time are persuading people to make efficient use of all available exits and reducing the queuing time at each exit. A system that can intuitively draw people towards the nearest emergency exit may optimise its use, allow travel distances to be safely extended, and enable more effective use to be made of the building.
In the great majority of commercial and industrial premises, the building’s fire alarm system is the most likely initiator of a warning about a potential threat to the occupants, although unfortunately security alerts are becoming more common. The typical audible/visual warning generated by the system obviously alerts the occupants to the fact that there is an emergency and that they should relocate or evacuate. But this does not provide any help or guidance on the optimum escape route. The reinforcement of audible/visual alarms with voice messages can help, but the effectiveness of any generalised warning system is heavily dependent on the type of premises. For example, at one end of the spectrum consider an offshore oil rig, where everyone present is very well aware of – and is trained to react to – the three main audible warnings, each with dedicated tones for: evacuate the facility; toxic gas; or fire. Contrast this situation with, say, any large public building such as a hotel, airport, shopping mall or concert arena, in which the majority of those present will be totally unfamiliar with the layout of the premises and the format of any warning signals. Research shows that there is often a considerable delay, caused by uncertainty and the fear of looking foolish, before crowds respond to a genuine warning signal. In buildings with frequent broadcasts of advertising messages or other high levels of general noise, the problem is magnified because people tune out background announcements.
No way out?
Traditionally the maps, markings and signage required by the appropriate codes of practice provide the occupants with a visible means for locating a path to safety. Exit signage is usually the primary means for locating an exit, supported by emergency evacuation plans and diagrams showing the locations of, and routes to, the exits. While emergency lighting provides restricted illumination in the event of a power failure, it will be inadequate once the exit routes are filled with smoke. Even if the power supply is not disrupted, the presence of even small quantities of smoke can cause dramatic reductions in the ability to see. Additionally in many shopping centres, there are so many notice boards, advertising displays and other visual clutter that the emergency exit signage is often overwhelmed. Many other public building have layouts where each floor is visually indistinguishable.
In an emergency, people – particularly in a crowd – do not behave rationally. The noise, confusion, concern for one’s family and fear of the unusual situation will all reinforce the primitive ‘fight or flight’ reaction. Normally, the instinctive reaction is to get out as fast as possible but as in the normal course of events people do not take note of where they are in the building, they will have no idea where to go in the event of an emergency. If people are unable to identify the nearest emergency exit, there is a strong tendency to retrace the route by which they entered the building, which will very often not be the most efficient exit route. Using the most familiar exit may also lead to crowding at the main entrance/exit while other viable escape routes are underutilised. Panic is more likely to set in if an exit route is not immediately apparent, particularly if the building is crowded and the danger is perceived to be severe and immediate.
To address the issues of effective premises evacuation, a new directional sound technology, which instinctively attracts people towards its source, has been developed at Leeds University and is now becoming available through commercial partners. The units generate broadband white noise, which is similar to many sounds found in nature to which humans instinctively respond (for example, running water or rustling bushes). This type of sound intuitively attracts the listener’s attention and draws them towards the source. The white noise, with an amplitude of at least 10dBA above the ambient background level, will cut through the hubbub and be clearly audible. In tests, conducted in pitch darkness in premises where, because of the location of the building in the side of a hill, the nearest escape route involved ascending stairs from the first floor – a somewhat counter-intuitive action – there were no problems in following the aural guidance and exiting the premises in a very short space of time by the shortest possible route.
The principle is that sound pressure waves arrive at the listener’s ears with slight differences in timing and volume depending on the frequency, relative position and distance of the source. The human brain interprets the electrical signals from both ears to give an accurate location for the source: above or below, in front or behind, near or far. As an additional benefit, as sound can travel around corners, no direct line of sight is required.
Smooth exit
In a typical application directional sounders are located at key points in the exit routes. Triggered by the fire alarm control panel, the directional sounder draws attention to exits and egress routes. The varying tones and intensities coming from directional sound devices offer easy-to-understand cues for rapidly finding exits. As soon as people hear the devices, they intuitively take notice of them to find the nearest available exit, thereby reducing exit flow time. In addition to the directional broadband output, different combinations of duty cycles, and rising or falling tones intuitively guide people up or down stairs.
The technology has a number of advantages. In 2005, over 50 people were killed and around 1500 injured in UK non-domestic buildings. The majority of those injured suffer from the effects of smoke or gas inhalation, the severity of which is normally directly proportional to the time of exposure. In addition to increased safety, the use of directional sound is particularly applicable for installations where the building owner would benefit from a performance-based approach to fire safety. Potential reduced evacuation time may allow the internal layout of the building to be configured for higher occupancy levels, or with longer emergency exit paths. By incorporating directional sound in the early stages of building design, there may also be opportunities to reduce the need for other fire and emergency systems, or to reduce risk and insurance costs in buildings or installations fitted with the technology. There may also be the opportunity to improve the use of available space, potentially giving the building owner the opportunity to improve the yield on the property. The relatively low cost of installing the directional sound technology could therefore also have an economic advantage over the lifetime of the building.
Standards covering the technology are starting to emerge: in the UK, BS 8456:2005 Code of Practice for design and installation of directional sounder evacuation systems has been published and a Publicly Available Specification, PAS41: 2003 covering performance requirements and methods of testing for directional sounders, has been published by British Standards Institution. At a meeting of a CEN/TC 72 task group considering evacuation issues, held in London in September 2006, a presentation was made giving information about a directional sounder system used to assist in the evacuation of buildings. Currently a BSI technical sub committee is reviewing PAS 41 and considering whether or not to propose it be developed to become an
EN Standard.
Mark Thomson is business development manager at KAC, a Honeywell company. The company markets the directional sound technology under the ExitPoint brand.
A LONG AND WINDING ROAD
When Oregon State University refurbished one of its halls of residence, the authorities were concerned that conventional escape route provision would not be sufficient for what is a complex building to navigate. In particular, the wings of the seven storey building are winding in nature, so corridors are curved and escape routes are not intuitive. By improving the ability to find exit routes using directional sounders, the university was able to make more effective use of student living quarters and improve safety.
Most of the university’s halls of residence are simply designed; for example, a student turns left or right out of their room, and then walks straight ahead to the stairwell at the end of the corridor. The GEM building, however, is more complicated. It is a seven-story, 120,000 square foot concrete building that was recently converted from a hall of residence with bed-sitting rooms to studio-style suites and one, two and three bedroom apartments. The food service area was also converted into loft units; altogether, 231 units were created. Each floor now consists of three wings and a central lobby with elevators. The wings are winding, so going around one corner does not necessarily bring you to a stairwell or exit.
Kurt Haapala, an associate with the buildings designers, Mahlum Architects, explains: "From the architect’s perspective, we normally try to meet the letter of the code when thinking about fire and life safety, as well as safety egress. However, when we walked through this building we were all left with a certain level of uneasiness about the egress route. It was particularly confusing to find the mezzanine level and not to know how to get in or out during an emergency."
ExitPoint incorporates sounders, positioned at perimeter exits and stairwells, to guide building occupants to the nearest exit quickly and efficiently in the event of a fire. Triggered by the fire alarm control panel, it uses broadband sound that evacuees intuitively follow to safety. Unlike standard fire alarm sounders, which simply alert people that there is a fire in the building, directional sound technology directs occupants which way to go – an ideal solution for the halls of residence. The installation at Oregon State makes it the first university in the US to use ExitPoint in a residence hall.
Fire prevention and protection specialist Steve Owens, who witnessed a demonstration of ExitPoint, urged his colleagues to test the technology in the GEM building. "Seeing the demonstration was really the turning point for me," he says. "We were able to utilise an area in the GEM building, bring the light level down to where it was virtually dark, add smoke and run through an evacuation scenario. It was extremely convincing. It became apparent to me that in a very short period of time, even someone unfamiliar with the building could find their way out, unassisted. I don’t know of any other system that could make that claim."
