Larger and more complex buildings can result in more complicated means of egress in an emergency. To address the problem, new forms of dynamic exit signage – technology that holds great promise for life safety practitioners of the future – are hitting the market and expanding their presence in modern buildings.
A few years ago, I made my first trip to an IKEA store. I quickly figured out that the store wasn’t designed with the American get-in-and-get-out retail model in mind. IKEA hit me with sensory overload and took me on a journey; I found myself following the crowds through the maze-like paths, curious what was around the next corner, losing track of time and the short checklist of items I went in for. What I thought would be a quick trip turned out to be a four-hour excursion.
The longer I was in the store, the more disoriented I became in relation to where I had entered. Even as I wandered in a retail haze, my fire-protection engineer mind kept asking, ‘How am I going to get out of here?’ I found myself seeking out the exits in every new section I entered. Although not always blatantly obvious, the travel distances to exits, number of exits, presence of fire doors and other fundamental fire-safety elements appeared to be in place, and code compliant. Even so, I was unsettled by the uncertainty of my direct egress route in the event of a fire.
Historically, static exit sign messaging has served the public well for fire emergencies and for buildings with simple egress layouts. But as complex egress layouts become more common in modern buildings – as in the IKEA I visited – it can be expected that occupants will face greater fire-evacuation risks than ever before. That’s why many safety experts are questioning whether the standard static exit signage is enough, considering the growing complexity of building layouts as well as the emergence of other public hazards, such as active shooter events, that require rapid movement of people to locations other than the main entrance.
The need for exit signage that captures people’s attention and redirects them in an evolving emergency – not only identifying an exit route but identifying and following the optimal egress path – has driven the development of a new generation of advanced, dynamic exit signage systems. Unlike the static nature of conventional exit signs, a dynamic exit sign can leverage technological advancements in sensors, controls and artificial intelligence algorithms (in advanced, and high-intelligence systems) to allow the exit signage system to adapt and display different information based on the real-time conditions in complex buildings. This can present a series of trade-offs between static and dynamic exit signage, however, which has resulted in debate among regulatory bodies. For dynamic exit signage with both persuasive and dissuasive messaging, the potential benefit is that it can deter occupants from following a direction of travel that may be blocked or otherwise unsafe due to a hazardous condition such as a fire, structural collapse, or an active shooter. Conversely, others worry that more complex egress signage could also create confusion and increase the time required for safe egress.
Although dynamic exit signs are not yet the ‘norm’ for buildings today, the market traction of these systems (e.g. Levels 1 and 2 – see sidebar) in buildings around the world are following a promising path. Despite their bright future, the construction industry has pushed back on the use of this technology and acknowledgement or adoption in codes and regulations is lagging behind. More research will be needed as technological advancement and further development of this technology continues. Despite barriers, progress continues. The sophisticated implementation of the advanced systems still has a way to go, but many observers believe in the role this technology has in the future of modern buildings.
Exit signage old and new
For nearly a century, exit signage has been a fundamental element of building and life safety through its role of demonstrating clear egress routes in emergencies. For decades, the NFPA and ICC standards have required occupancies with two or more required exits or exit accesses to be provided with illuminated signs that readily identify the location of, and indicate the path of, travel to the exits. Most conventional exit signs include a static light source powered by the building’s electrical system. These signs have no controllable elements, however, as their appearance and illumination are fixed regardless of the situation.
The design requirements of conventional exit signs are generally fixed, apart from a few local variances around the world. UL 924, Standard for Safety of Emergency Lighting and Power Equipment, specifies how static exit signs are to be designed and manufactured; requirements set by standards such as NFPA 101®, Life Safety Code®, or the International Building Code (IBC), define the performance of exit signage primarily through placement and visual characteristics. In support of broad awareness and recognition of exits, the type and simplicity of the signage, visual accessibility, architectural features and other characteristics – including font types and sizes, shapes of pictograms and styles, and the illuminance and colours of the light – are generally standardized and regulated through codes and standards.
Code requirements for the type, characteristics and placement of exit signage typically assume traditional designs, without differentiating between simple and complex buildings. Despite the rapid innovation in architectural design and the increasing complexity of modern buildings, the design of conventional exit signs has remained unchanged for decades and lacks the ability to adapt to changing environments or emerging threats that may arise in complex assembly occupancies. Given the speed of fire development and spread and the rapid evolution of other potential hazards, what may typically be a safe, useable egress route could be blocked or impaired during an emergency. Due to its static nature, however, traditional exit signage can convey a persuasive message regardless of the threat situation down the egress pathway or through the exit door. This has been illustrated in an array of fire incidents, including the Beverly Hills Supper Club (1977), the Scandinavian Star disaster (1990), the Station nightclub fire (2003), the Daegu subway fire (2003) and others. Additionally, recent research has found that fewer than four in 10 people perceive conventional static exit signs and use them to find their way out of a building under emergency conditions, even when the signs are unobstructed and located directly in their line of sight. Findings like these prompt questions as to whether static exit signage is enough to protect occupants in modern buildings, and in the buildings of the future.
That question underlies much of the work taking place to develop sophisticated alternatives to static exit signage, approaches driven by the rapid advancement of Internet connectivity and artificial-intelligence-based technologies. This technological revolution has unlocked opportunities to transform a simplistic, illuminated static exit sign into a dynamic exit signage system that exchanges data in real time to guide occupants to safety.
Unlike conventional static exit signs, dynamic exit signs are not stand-alone devices but are often part of an integrated, intelligent system, requiring a control system, sensors, and data communication and processing – and creating such a system presents a number of challenges. Existing sensor data, including information from smoke and heat detectors, must be open to the exit signage system, including the location of sensors in order to characterize the time evolution of smoke density and temperature to characterize the hazard evolution in a space. A centralized data-processing system must be established to gather and process information from the networks of sensors, and algorithms must be created to display different light patterns on dynamic exit signs in hundreds of time-varying fire scenarios. The algorithms must then be implemented into the processing and control system to realize the real-time control of the dynamic exit signs.
Development of such an intelligent system is complex and is largely dependent on the progress of other technologies, such as new sensors, the Internet of Things, computer vision, cloud computing, artificial intelligence and smart firefighting systems. To help define the current state of dynamic exit signage technology, the Fire Protection Research Foundation recently published a study that included a review of the types of dynamic exit signage systems currently under consideration, ranging from commercially available systems to technology that is still largely theoretical (see sidebar). While the study underscored the complexity of such systems and the numerous technological gaps that exist in their development, it also suggested the vast promise these systems hold for improving life safety in an array of applications. Decades of continuous research and development will be required to advance the concept of the dynamic exit sign system and its integration with other smart fire, life safety and building systems.
Case studies and looking forward
As dynamic exit signage systems gain traction worldwide, studies have been conducted to demonstrate the effectiveness of these systems.
For example, a case study conducted in the UK compared occupant response and evacuation efficiency with static signage versus dynamic signage. The dynamic sign utilized an exit sign that under normal operating conditions looks identical to a standard static pictogram emergency exit sign; under emergency conditions, however, the sign became dynamic. Two different dynamic exit signage types were tested. One type was a fixed dynamic exit sign where the fire-alarm panel sent signals to the exit signage to provide a dynamic pulsing array of green lights within arrows on the sign to draw attention to the sign and encourage the use of a particular exit. The other type was an adaptive exit sign that had the same characteristics as the fixed exit sign, except that when an exit was no longer encouraged for safe egress, the fire panel communicated with the dynamic exit sign to display a red cross across the sign to dissuade occupants from using that particular exit or egress path.
These evacuation trials, involving 152 occupants, found that occupants tended to use the closest exit in the static signage scenarios, and that the signage itself played a minor role in their decision making. By comparison, dynamic exit signage significantly influenced participant exit route choice by dissuading occupants from using the closer, non-viable exit and encouraging movement toward more distant exits with safer egress paths. In this case, the dynamic exit signage system increased the signage recognition rate by more than 60%, facilitated a 50% faster evacuation, and improved evacuee decision-making by 44% compared to static signage. These are remarkable results, considering that the standard occupant response when only static exit signage is present is to go to the nearest exit or back to the door where they entered, actions that underscore the passive nature of static signage and its relatively weaker influence on changing occupant behaviour. The dynamic concept, therefore, appears to address a significant weakness of conventional signage systems by providing a means to adapt the guidance according to the developing hazard environment. However, trials participants indicated that when negative information is conveyed on the sign, it should be coupled with positive exit route information to reinforce the desired action.
Another case study, conducted in Australia, used dynamic signage in an attempt to increase exit signage visibility, provide audible cues and offer dissuasive messages to evacuees. The dynamic elements of the signage boosted the sign detection rate by 77% and decreased evacuation time by 40%.
While such results are promising, gaps remain with respect to standards, technology and knowledge that are limiting broader public acceptance of the various levels of dynamic exit signage, as well as its adoption in standards and its broader implementation. Although some of the more simplistic types of dynamic exit signage have been able to successfully comply with regulatory requirements for static signage, established standards generally lack guidance on the positioning of dynamic exit signage, display methods and patterns. Additional gaps include guidance on the greatest allowable complexity; underdeveloped technologies that can lead to reluctant public acceptance, tentative adoption of networks and algorithms, and unauthenticated objectives; and a need for additional case studies and research on the actual implementation of dynamic exit signage and its impact on human behaviour, the impact of smoke on dynamic signage performance, and more.
The various type and levels of intelligence of dynamic signage systems correlates to different levels or market viability, availability and implementation in modern buildings. While advanced dynamic exit signage systems requiring a high level of intelligence are still a fairly new concept in industry and in academia, with the increasingly intelligent systems still primarily in the research and development stages, the more simplistic systems (Levels 1 and 2 – see sidebar) are increasingly being deployed in existing building applications. Given that academic research, codes and standards, and existing building applications are still fairly limited, sophisticated implementation of advanced dynamic exit signage systems still has a way to go. Based on the early promise shown by this technology, however, researchers and professionals must continue to investigate its impact on human behaviour, implement additional real-life experiments, and continue introducing emerging technologies into these systems. Our safety future requires it.
Smart and smarter
A range of approaches to dynamic exit signage
To define the current state of dynamic exit signage technology, the Fire Protection Research Foundation initiated a study, ‘A Review of Dynamic Directional Exit Signage: Challenges and Perspectives’, which it published in 2023 (nfpa.org/dynamic). In partnership with Hong Kong Polytechnic University, the project reviewed the type and state of the available dynamic exit signage technology and connected systems, relevant regulations and prevalence of use, and the use of dynamic exit signage in buildings and its impact on evacuation. It also identified gaps in regulations, technology and knowledge that are barriers to further implementation.
In the report, the authors identified four levels of dynamic exit signage systems, distinguished by levels of technological maturity and intelligence:
Level 1: Flashing lights
The first level – flashing lights on an exit sign – is the most basic fixed dynamic exit sign, as it only emits a flashing light to emphasize a desired action.
To operate, each sign either has independent hardware activated by nearby sensors or is part of an exit signage system similarly managed by a central control panel. The latter system requires all exit signs to connect to the fire panel, inclusive of heat and smoke detectors. Upon receipt of an emergency signal, occupants’ attention will be drawn toward the flashing lights on the exit signs, alerting them to an emergency. The flashing lights may be integrated into the exit sign or installed externally on the surface. Systems of this type are readily available on the market and have been incorporated into a number of assembly occupancies around the world.
Level 2: Persuasive and dissuasive design
The second level of dynamic exit signage offers more directional information, including dynamic arrows, Xs, emergency voices and additional text.
These dynamic signs respond to a fire detected by fire or smoke sensors within a building by displaying persuasive and dissuasive signals. To achieve this type of dynamic system, the intelligence level of the system must be capable of evaluating the fire scene by examining the time and location of each sensor in conjunction with video footage from closed-circuit television cameras. Most fire panels available today can provide such information, which leads to the need for exit signage systems with similar intelligence levels to be connected to an existing fire control panel to gain access to raw sensor data and alarm information. The signs can then show a dissuasive signal, such as a red X, as a way to prevent evacuees from getting closer to the source of the fire. This type of system can be deployed at a relatively low cost in existing buildings, as it leverages existing sensors and fire panels. With its availability on the market, this type of dynamic system is gaining significant traction globally.
Level 3: Digital twin integration
This level offers a high level of intelligence and sophistication. These systems include a digital building twin – a virtual replica of a physical building with all of its associated technologies, systems, equipment, sensors and actors – that can warn occupants against entering dangerous areas and guide them to evacuate through the most efficient path to safe egress.
This dynamic signage system acts as a sub-system in the digital twin of a smart building. By collecting sensor data such as temperature and smoke visibility from IoT devices in the building, a digital twin can leverage AI to predict and render a dynamic fire scene in a building. By recreating the real-time fire scene and forecasting fire evolution, the system can compute optimal egress paths in real time and use dynamic exit signs to indicate them. The 2D or 3D digital model of the building allows users such as building managers and the fire department to view depicted fire scenarios in every room, in addition to observing the status and flashing pattern of each dynamic exit sign. While this system presents technological sophistication that provides a real-time, data-driven approach to support safer egress, many concerns and challenges exist relating to system reliability, liability and operator skill level, compounded with the challenges identified for second-level systems.
Level 4: Dynamic exit signage systems with advanced human-computer interaction
While many of the required technologies for this type of system are still in the research and development phase and are not yet mature enough for market-ready solutions, they are developing rapidly.
These systems are anticipated to build on the characteristics of third-level systems by visualizing the position and motion of all occupants in a building’s digital twin based on camera footage and the use of human behaviour models to forecast the bulk motion of the evacuation flow, including potential congestion and the evacuation time of each person. If the system is damaged by fire, occupants can still receive information about unsafe areas and optimal evacuation paths via mobile devices and augmented reality glasses, or through the use of unmanned aerial vehicles and robots that can enter the fire scene and assist with the evacuation process.
About the Author
Victoria Hutchison is a research project manager at the Fire Protection Research Foundation, the research affiliate of NFPA. Victoria conducts, manages and facilitates research on behalf of the NFPA mission on a variety of fire protection and life safety related issues.
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