Workplace Illumination – Part 16: Safety, Security, and Emergency Lighting

            Superficially, lighting for safety, security, and emergency situations may seem redundant.  While there is overlap among these lighting scenarios, they are differentiated by their primary purposes, operating conditions, and characteristic requirements.  There is also an interdependence among these lighting scenarios, despite independent operation in the majority of circumstances.
            In this installment of the “Workplace Illumination” series, the characteristics of safety, security, and emergency lighting are explored.  What separates them and what unites them in a cohesive lighting system design is discussed to enhance understanding of each lighting scenario and recognition of their interdependencies to support effective installation and maintenance.

Safety Lighting
            Safety is a relative term, as it is impossible to eliminate all risk from any activity.  This distinction is integral to the definition of safety lighting:  a system of lamps, luminaires, controls, and material properties used to mitigate risks associated with an activity or inherent in a space.  Risks can be mitigated, but not eliminated, with effective lighting; undesirable or unpredictable behavior, individual capacities, and other uncontrollable factors (e.g. acts of nature) ensure that some risk remains.
            Safety lighting is one aspect of an organization’s safety culture.  Done well, it contributes to a low occurrence rate of incidents.  However, this correlation must be reinforced in organizational communication to prevent complacency and risk-tolerant behavior from negating the benefits that effective safety lighting provides.  See “Safety First!  Or is it?” [16Dec2020] for a discussion of safety culture and vocabulary.
            The defining purpose of safety lighting is the protection of people; it is required to function any time a space is occupied.  Most often, it is associated with “normal operations” in indoor spaces; however, it is not limited to this scenario.  Periods of reduced activity and outdoor spaces may also require safety lighting, though the operating parameters may be significantly different.
            Common workplace accidents include slips, trips, and falls.  Surface conditions must be monitored to remedy temporary hazards, such as liquid spills, as quickly as possible, while lighting provides awareness of the hazard in the interim.  Lighting is often the primary mitigation technique for permanent hazards, such as an uneven surface or non-standard step height, while signs and special markings increase awareness.  Such conditions may exist inside a facility or on a sidewalk, parking area, etc. external to it.
            Collisions with stationary objects or mobile equipment are also common.  The risk increases with the number of convergent paths and number of travelers.  Safety lighting improves visibility at intersections and increases accuracy of speed and distance judgments.  Collisions are often associated with material-handling equipment (e.g. forklifts, cranes), but can also occur with other vehicles, pedestrian traffic, automated equipment, etc.  The potential for collisions of the head, specifically, in cramped workspaces or during procedures performed outside normal parameters (e.g. equipment repair) should also be evaluated when considering lighting as a preventive measure.
            The contributions of lighting to accidents include the usual suspects.  Insufficient illuminance and low contrast limit visibility of hazards.  Direct and reflected glare, as well as deep shadows, can also obscure hazardous details.  Any combination of conditions that accelerates visual fatigue or eyestrain contributes to accident occurrence.
            Flicker increases the risk associated with rotating or oscillating equipment by distorting observers’ perception of its movement.  Incomplete adaptation, due to moving between spaces with significantly different illuminances, also increases risk of accidents.  Pausing to restore visual capability in new conditions before engaging in demanding visual tasks substantially reduces risk.
            Where possible, this transition time, spent idle, may be supplanted by a transition space, in which low-risk activities are conducted while visual system adaptation occurs.  This is the technique used in many building lobbies; visitors transition between interior and exterior conditions in two or more stages.  The adaptation process becomes less noticeable and the transition less visually taxing.
            In brief, to be effective, safety lighting must not only be present, but appropriate for the space, tasks, and individuals.  First and foremost, the lighting system must not create a hazard.  Avoiding the pitfalls mentioned above are key to this objective in any environment.  In some environments, however, additional precautions must be taken.
            In addition to temperature and humidity considerations, the presence of flammable gas, combustible dust, or similarly-dangerous airborne substance requires the specification of luminaires suitable to such an environment.  A summary of area classifications and luminaire types appropriate for each is shown in Exhibit 1; see “NFPA 70” for detailed information.  See Part 11 for basic luminaire information.

            Illuminance recommendations for various combinations of activity level in a space and the degree to which the space is hazardous are given in Exhibit 2.  Descriptions of the activity levels used in these recommendations are provided in Exhibit 3.  The low illuminances recommended, with no adjustment for observers’ age, suggests that maintaining a minimum level of safety is not visually demanding.  As is the case with other lighting recommendations, specific attributes of a space or its occupants may warrant deviation from these values.  Satisfaction of regulatory requirements must always be verified before finalizing a lighting system, whether deviating from published recommendations or strictly adhering to them.

Security Lighting
            Security is the extension of safety from the physical to the psychological realm.  Psychological safety is achieved by mitigating concerns of potential hazards, particularly criminal activity.  Thus, security lighting is a system of lamps, luminaires, controls, and material properties used to deter crime and unauthorized access to a site or space and increase the probability of detection, identification, and apprehension of perpetrators, thereby enhancing the perception of safety of persons and property.
            Safety lighting creates favorable conditions for all occupants of a space.  Security lighting creates advantageous conditions for authorized occupants by simultaneously creating difficult visual conditions for unauthorized occupants.  This method is often associated with exterior applications, but can also be used effectively to protect interior spaces.  It is active during normal operations; when a site is unoccupied, its mode of operation may be modified.
            A common application of security lighting is the site-entry gatehouse; an example is depicted in Exhibit 4.  Sites with stricter access-control requirements, such as nuclear processing facilities and military installations, use multiple techniques to increase the visual advantage provided to security personnel.  Requirements vary according to the type of traffic being controlled.  Pedestrian traffic requires sufficient illumination at face-level to identify each person and color-rendering capability sufficient to accurately describe attire and appearances (CRI > 80 is typically deemed acceptable).

            Vehicular traffic poses additional challenges.  In addition to identification and description of each passenger, it may be necessary to scan the entire vehicle interior for unauthorized objects or materials prior to entry and for contraband before exiting the site.  Inspection of the vehicle undercarriage may also be necessary, requiring high illuminances at ground- and near-ground levels.
            Large vehicles, such as delivery vans and freight trucks, further complicate inspection of the vehicle interior.  When the passenger compartment is above guards’ sightline, an elevated platform may be necessary to interact with the driver effectively and to scan the interior.  A potential offset may exist when undercarriage inspection is facilitated by greater ground clearance.
            In addition to intentional glare, gatehouse windows may be covered with a material with a high-reflectance outer surface and low-reflectance inner surface.  Windows may also be angled to minimize reflections from interior lighting, as shown in Exhibit 5.

            Interior conditions of a gatehouse can also be controlled for maximum security.  Minimum illuminance, provided by targeted lighting (i.e. shielded or directional luminaires), limit visibility of the positions and activities of personnel from outside the gatehouse.  Use of dark colors and low-reflectance materials further inhibits monitoring of personnel.  Positioning and brightness of self-luminous displays (SLDs) must also be carefully planned to prevent highlighting faces or hindering outward visibility.
            Lighting of the property barrier, extending from the gatehouse to surround the site, must also be considered; areas most vulnerable to intrusion should be best protected.  If a solid barrier (i.e. wall) is in place, lighting it from above minimizes shadowed areas on both sides in which intruders can hide.  Lighting of building facades serves a similar purpose, depriving a potential intruder the cover of darkness in which to gain unauthorized access to the structure.  This approach may be used in the absence of a site barrier or as an additional deterrent.
            Chain-link fence is more common than perimeter walls; its installation prompts additional lighting system design decisions that must be made to ensure the effectiveness of security lighting.
            A key decision to be made is whether the fence should be used to obscure details of the site or if high visibility is to be maintained.  For example, patrols conducted outside the perimeter fence are able to monitor activity along the fenceline and on the site grounds if visibility through the fence is maintained.  Low-reflectance materials aid visibility through a fence, while high-reflectance materials and reduced mesh size increase obscurity.  Like the windows of a gatehouse, these properties can be applied selectively to bias visibility as desired.
            The methods of intrusion anticipated influence the placement and aiming of luminaires.  For example, an intruder may climb over a fence, tunnel underneath it, or cut a hole in it.  The probability of each method of intrusion informs the specification of perimeter lighting.
            Parking facilities inside a secure site benefit from controlled access and routine monitoring; safety lighting may be sufficient to provide a sense of security among its users.  This is not the case in unsecured parking areas; users are much more exposed to potential threats, increasing the importance of proper security lighting.
            IESNA has recommended open parking areas be provided a minimum horizontal illuminance at ground level of 30 lx (3.0 fc) with an average-to-minimum uniformity ratio of 4:1 and vertical illuminance at 1.5 m (5 ft) above ground level of 3 lx (0.3 fc).  Sidewalks and other adjacent areas should be provided horizontal and vertical illuminances of 6 lx (0.6 fc) to allow identification of other persons in the vicinity.
            Enclosed parking structures pose an increased threat to users due to relative isolation and limited visibility.  A commensurate increase in illuminance is recommended to 60 lx (6.0 fc) minimum horizontal at ground level and vertical at 1.5 m (5 ft) above, with average-to-minimum uniformity ratio of 4:1.  With little daylight penetration typical of these structures, electric lighting is relied on to maintain the recommended illuminance levels at all times.

            Interior security lighting can function similarly to that on the exterior in some applications.  Examples include screening areas, such as those at entrances to municipal courthouses and airports.  Lighting the walls in public spaces with uncontrolled access, such as transportation platforms, can eliminate miscreants’ hiding places.  These examples are for normal activity in occupied spaces; security lighting is also used to protect unoccupied spaces.
            The absence of occupants shifts the function of security lighting exclusively to the protection of property.  A prominent example is the lighting of retail spaces that are closed for business.  A darkened exterior and glass façade make the presence of a person in the lighted interior easy to detect by a passerby or police patrol.  An alternative to fully lighting the space is to strategically place luminaires such that an intruder’s silhouette is projected to the façade for detection.  Motion-activated lighting also makes an intruder’s presence obvious.

            When video surveillance is in use, it must be integrated with the lighting system to ensure its effectiveness.  Haphazardly-placed cameras could be rendered ineffective if glare from security lighting “blinds” them by oversaturating its image or similar interference.  This is equally true for interior and exterior applications, though the installation challenges differ.

            Security lighting requires customization for the types of threats anticipated to both persons and property; these define the visual tasks it must support.  Illuminance, uniformity, surface reflectances, background luminance, color properties, and a newfound appreciation of glare are important factors that influence design decisions and system performance.

Emergency Lighting
            The primary purpose of emergency lighting is the protection of people, though some applications may also include a property-protection component.  It consists of escape lighting and standby lighting.
            Standby lighting is often associated with facilities that cannot be immediately evacuated in an emergency.  Hospitals and some processing plants are common examples where immediate evacuation creates additional hazards or causes loss of life.  The need to continue life-supporting treatments in a hospital is obvious; the need for standby lighting and auxiliary power in an industrial facility may be less so.  However, some industrial processes can become very dangerous if a controlled shutdown process is not followed.  When the greatest risk is of equipment damage or excessive material loss, the consequences are much less severe, but standby systems may be in place to allow these procedures to be followed when safety of personnel can be maintained while doing so.
            Of greater import to this presentation, escape lighting provides visual stimuli to aid evacuation of a space in an emergency situation.  It may also be called egress lighting, though this term seems more appropriate for use in normal conditions, when exit markings guide a visitor through a space, but the consequences of a wrong turn are miniscule.  Every escape lighting application contains sufficient nuance, equipment options, and regulatory variability to force this presentation to be only an introduction to the topic.
            Emergency lighting is a system of lamps, luminaires, auxiliary power sources, and self-luminous signs used to aid evacuation of a facility and/or execution of critical response procedures when normal operations cannot be sustained and/or dangerous conditions exist.  The most common emergency situations are power outages and fires.  The matrix in Exhibit 6 summarizes typical occurrences of these, both independent and simultaneous.  Standby lighting activation is indicated in the no-power scenarios; however, this is only true for installations, such as the examples cited above, in which standby systems have been integrated.  Escape lighting is required in all facilities; standby lighting is not.
            It should also be noted that a power outage does not always prompt an immediate evacuation; a “shelter in place” order may be the norm.  However, if power is not restored in a timely manner, evacuation becomes necessary; emergency lighting is intended only for short-term use.  The facility must be evacuated before escape lighting begins to falter.

            Emergency lighting can be powered by a generator or battery backup.  Either type of system must activate automatically when the primary power source is lost.  A sophisticated system may utilize both types, initially using battery power for rapid activation upon power loss.  Once a generator is operating, lights are switched to this source, conserving the batteries, to ensure that extended use is uninterrupted.
            The majority of escape lighting is located inside a facility.  However, evacuation may require lighting paths and assembly areas at a safe distance from the structure.  Existing safety lighting may be powered by an emergency backup source for this purpose or a separate system may be installed.
            An escape lighting installation can include a combination of wall- and ceiling-mounted luminaires and self-luminous exit signs and path markings.  The following points provide a brief description of an emergency lighting design process, highlighting important aspects for consideration.

• Identify all exits and emergency exits.
• Plan escape routes from every area within the facility, including exterior paths and assembly areas.  Plan alternate routes to ensure unforeseen circumstances do not leave occupants trapped or bottlenecked in merging escape routes.
• Define all areas and processes requiring standby lighting.
• Identify all points on all escape routes that require a direction change, surface condition warning, or other message to be visible in emergency situations.
• Identify all emergency equipment stations that require lighting.
• Identify all isolated areas, such as restrooms, that require emergency lighting to prevent disorientation, trips, falls, etc.
• Consider additional lighting and signage that may be needed in areas occupied by persons unfamiliar with the building, its escape routes, or emergency procedures.
• Consider the effect of smoke on visibility of escape route markings; it may be necessary to install floor-level signs or relocate luminaires that could obscure exit signs or other path markings.
• Specify the number of each type of emergency lighting luminaire, self-luminous sign, path marking, etc. required for all escape routes, isolated rooms, stairwells, escalators, elevators, fire equipment stations, and any other location necessary.
• Design emergency backup circuits for all luminaires that are not self-contained (i.e. standalone battery backup units), including any standby lighting specified above.
• Define test and maintenance procedures and schedules for all emergency lighting components.
• Verify visibility of all escape route markings and efficiency of evacuation routes prior to occupancy and any time that layouts or other conditions change.

            Consult the latest version of all regulations to which a site is subject to ensure that all emergency lighting requirements are met.  Illuminances, sign color, textual vs. graphical signage, and other requirements are subject to change.  A mix-and-match approach is not desirable and is often prohibited; ensuring compatibility of all components at the outset saves time, money, and frustration for the entire project team.
            The concepts presented here serve only to introduce readers to the many aspects of safety, security, and emergency lighting that must be considered to ensure the protection of persons and property in all foreseeable situations.  The references cited below are excellent resources for additional information on related research, recommendations, and regulations.


            For additional guidance or assistance with Safety, Health, and Environmental (SHE) issues, or other Operations challenges, feel free to leave a comment, contact JayWink Solutions, or schedule an appointment.

            For a directory of “Workplace Illumination” volumes on “The Third Degree,” see Part 1:  An Introduction to Lighting (21Aug2024).

References
[Link] Lighting for Health and Safety.  N.A. Smith.  Butterworth-Heinemann; 2000.
[Link] The IESNA Lighting Handbook, 9ed.  Mark S. Rea (ed).  Illuminating Engineering Society of North America; 2000.
[Link] The IESNA Lighting Handbook, 10ed.  David L. DiLaura, Kevin W. Houser, Richard G. Mistrick, Gary R. Steffy (eds).  Illuminating Engineering Society of North America; 2011.
[Link] Human Factors in Lighting, 3ed.  Peter R. Boyce.  CRC Press; 2014.
[Link] “NFPA 70:  National Electrical Code.”  National Fire Protection Association.
[Link] “NFPA 101:  Life Safety Code.”  National Fire Protection Association.
[Link] “ANSI/IES RP-7-21 Recommended Practice: Lighting Industrial Facilities.”  ANSI.

Jody W. Phelps, MSc, PMP®, MBA
Principal Consultant
JayWink Solutions, LLC
[email protected]