By Ulrich Höfer. Optical dynamic escape routing is essentially an addition to conventional emergency and safety lighting connected to an automatically triggered power supply. In the event of a power cut, the latter ensures that certain areas are still lit, and that emergency exit luminaires and direction-giving signs are front or back lit as appropriate. This signage is either replaced or supplemented by a dynamic escape routing system.
The source of danger: dense smoke
Unlike conventional emergency and safety lighting, dynamic escape routing is triggered by a fire emergency, not a power failure. To give an example, burning 1 kg of paper produces around 800 m³ of dense smoke. People lose consciousness after two or three breaths of fire smoke. Around 85% of all fire victims subsequently die of smoke inhalation. This means the worst problem in a fire is the smoke, not the flames!
Because smoke is hot, it rises to the ceiling: both general and safety lighting become ineffective, and high-level emergency exit are no longer visible. Anyone trying to escape is moving in complete darkness and cannot find their way. At the same time, an area forms above the floor that is smoke free or almost (depending on room height, etc.). In this metre-high zone, finding one’s way and surviving becomes possible.
The lifesaving solution: flexible way guidance
Dynamic escape routing offers way guidance to people in a smoke-filled area. It must therefore be installed close to the floor. By indicating the direction of travel, ideally in conjunction with a run-light function, it can signpost the shortest way out of the danger zone. At the same time, the system must prevent people from fleeing into a smoke-filled area. Consequently, it must be possible to alter the signs indicating the escape routes. This means that static emergency exit luminaires must be replaced, at least in part, by luminaires with dynamic direction indicators.
Dynamic emergency exit luminaires need to be able to indicate alternative escape directions, and to close off an escape route endangered with a cross. It is also essential that the high-level luminaires indicate the same escape direction as the low-location way guidance. For the system to function, a fire alarm system must be installed in the building. This transfers messages about an event in the building to the escape routing system, where they are processed to control the dynamic luminaires. To guarantee the guidance system‘s operational reliability even in the event of a power cut,for safety purposes it must be connected to an automatically triggered power supply. This may be a central power system or another secondary power source (2nd grid/generator….) with a rated operating time of at least 60 minutes.
Mode of operation: adapted to the situation
The general mode of operation for optical dynamic escape routing should be clear from the layout plan below. The floors are divided into four fire/smoke compartments. The two escape staircases are located on two opposite corners of the building. According to current regulations, only the first escape route needs to be signposted. If it cannot be used (for example because of a fire occurrence, which can also be located on another floor, compromising the escape route), evacuees will need to find the second escape route. This will be difficult, as it is not signposted. Valuable evacuation time will be lost.
Evacuation: as straightforward as possible
A dynamic escape routing system assists an effective evacuation during a fire. A fire alarm system in the building recognises the fire and sets the evacuation in motion by controlling the escape routing system. A signal message can be sent to the routing system if the smoke spreads further so that the escape route signposting can be constantly adapted to the evolving situation. Admittedly, a prerequisite for this is a highly complex fire control matrix. Elaborate programming is required for both the fire alarm system and the escape routing system, together with a time-consuming check of the complete system.
An analysis just of the first fire occurrence simplifies the complete system enormously. Modern buildings are equipped with constructional and technical fire protection – a fire occurrence is therefore normally confined to a single fire compartment. Centralising all the smoke detectors in a fire or smoke compartment on a single signal message makes the escape routing system more simple to control. As soon as one of the compartment’s smoke detectors detects smoke, the affected area is visually closed off and the routing system indicates a route leading away from or around it. In the danger zone itself, the system indicates the shortest way out of it. The system then stores this scenario. There is no further alternate routing. This produces a clear fire control matrix, making it possible to run a simple function test on the complete system.
Application fields: many
In Germany the technical rules for workplaces (ASR) stipulate in which cases a dynamic escape routing system is to be used: “It is required to be installed where a heightened risk exists because of local or operational conditions. A heightened risk may exist, for example, in large interconnecting or multi-storey building complexes, where a large percentage of the persons present are not familiar with the surroundings or where a large percentage of persons present have limited mobility” (extract from ASR A2.3 of August 2007).
In new builds, building renovations or even in listed buildings, a dynamic escape routing system can be employed as a compensatory measure where there are deviations from the building code.
Dynamic escape routing as a compensatory measure
Dynamic escape routing can be employed as a compensatory measure in new builds, building renovations or even in listed buildings, where there are deviations from the building code.
Building code fire protection requirements are sometimes difficult if not impossible to meet when renovating historical buildings, in particular. Solutions then have to be found that retain the unique characteristics of historical buildings but at the same time are compliant with both modern-day fire protection demands and heritage protection requirements. Compromise is frequently necessary when juggling regulations and heritage protection requirements, and compensatory measures have to be found that are compliant with the protective aim of enabling people to rescue themselves.
The creativity of property owners, architects and specialist fire protection planners is often curtailed by building code fire protection requirements when planning new builds, special constructions or special-purpose structures, renovations or conversions, as well. They might want to add architectural aspects, such as transparency, certain functions, or aesthetic details, that are only possible to a limited extent if they are also to comply strictly with legal regulations. Such building plans can only be realised by incorporating technical measures to compensate the deviations. The use of dynamic escape routing can enhance both scope and flexibility when designing a building.
The town of Altena was planning to build a pedestrian tunnel with lift to Altena Castle. The entrance structure leading to the tunnel is accessed from a public traffic area. The tunnel is 93 m long with a lift at the end to take visitors up to the castle. In normal operation, the tunnel is accessed from the entrance building. In order to create an escape route out of the tunnel and enable access for the fire service without having to go through the entrance structure, a bypass between the entrance building and the tunnel was planned that leads straight out into the open (see Fig. 4).
The tunnel’s length of 93 m exceeds the 35 m length of escape routes that is permissible under building code regulation § 37 BauO NRW by a quite considerable margin. As such, the building code-specified protective aim of ensuring an escape route was a central function of the structure. Added to which, the structure does not have a second escape route, which constitutes a deviation from building code regulation § 17 (3) BauO NRW (see Fig. 5).
To compensate these deficits, the tunnel was equipped with fire seals, the lift is designed as a firefighters’ lift, and dynamic escape routing was put in place:
- Two fire seals split the tunnel into three sections, with a lock system separating it from the area in front of the lift.
- The firefighters’ lift gives the fire service access to the tunnel from the castle in an emergency. To ensure the functional reliability of the firefighters’ lift, a protective smoke pressure system was installed in the lift shaft and the area in front of the lift.
- The dynamic escape routing system – comprising dynamic emergency exit luminaires at head height and dynamic arrows at floor level – indicate the escape route to be used in each case. The lights flash to attract enhanced attention (see Figs. 6a and 6b). A fire alarm system that monitors the entire area controls the dynamic escape routing.
If evacuation of the tunnel becomes necessary due to a damage incident that is not, however, affecting the entrance structure, people are led out through the entrance building into the open.
In the event of a fire in the entrance structure, however, a T90 sliding fireproof door at the entrance to the tunnel closes and people are led out through the emergency exit door in the bypass.
In the event of a fire in one of the three fire sections in the tunnel, people are led out of the affected area by the shortest route, either through the entrance building or the bypass, or through the lock leading to the front of the lift. The area in front of the lift is deemed to be safe because its separation from the tunnel is fire protection-compliant and it is equipped with a protective smoke pressure system. People who have been led there by the dynamic escape routing system can wait there until the fire service comes down the lift to rescue them. The fire protection concept for the planned infotainment lift to Altena Castle was designed by engineering firm Kempen Krause Hartmann Ingenieurgesellschaft mbH.
A dynamic escape routing system is an orientation aid at floor level that shows the safe way out and makes sure people do not flee into a smoke-filled area. In the event of a fire, it enhances visitors’ safety and is a suitable compensatory measure.
Dipl.-Ing. Ulrich Höfer: Dipl.-Ing. Ulrich Höfer studied electrical engineering, worked for a number of years in planning and construction management of a major project in the field of safety technology for an international company; moved to INOTEC Sicherheitstechnik GmbH in 2002, where he is responsible for fire safety concepts as well as project and product management in the area of dynamic escape routing systems