10 May Designing Egress and Emergency Lighting: Planning for the Worst When Scoping Your Lighting Retrofit
Many lighting retrofit designs fail to fully consider egress and emergency lighting systems. These systems are usually required by state code and often superseded by local code or the requirements of the local authority having jurisdiction. Failure to provide adequate egress and emergency lighting controls can spell liability trouble in the event of an injury. Conversely, providing too much egress lighting can result in wasted energy and higher first costs for retrofit projects. As project developers, it’s critical we make sure to present safe lighting retrofit solutions that don’t make sacrifices. In this post, I’m sharing my experience working with a client who had to satisfy both California state building codes and NFPA 101 building codes.
An Intro to Egress and Emergency lighting
Egress lighting is the lighting that provides a clear view of the path of egress, enabling occupants to leave a building during normal circumstances when occupied.
Emergency lighting is the lighting systems active on the path of egress during a loss of power event and, in some code requirements, when the fire alarm is activated. Emergency lighting systems are intended to provide back-up power to a lighting system while occupants evacuate a building.
Building Code Requirements
Today’s post discusses the relevant code requirements in California:
- California Building Code (CBC)
- NFPA 101
- Chapter 7 – Applies to New Construction
- Chapter 39 – Applies to Existing Building
The Path of Egress
NFPA 101, CBC, and IFC use the following definition for the means of egress:
A continuous and unobstructed way of travel from any point in a building or structure to a public way consisting of three separate and distinct parts (1) the exit access, (2) the exit, and (3) the exit discharge.
To put this in layman’s terms, the means of egress is a path that will take any occupant out of a building or facility and past the property line, where said occupant is no longer the building owner’s (and thus designer’s) problem. This means exterior lighting on a property or campus will likely need emergency lighting provisions.
California Building Code Path of Egress Lighting Requirements
The path of egress needs to be lit and there are multiple requirements in the code;
§1008.2 Illumination Required: The means of egress serving a room or space shall be illuminated all times that a room or space is occupied.
The following areas are exempt from this requirement: utility spaces (Group U occupancies), aisle accessways in assembly buildings (Group A occupancies), dwelling and sleeping units in unsupervised residential occupancies (e.g. non-nursing homes), sleeping units in institutional buildings (e.g. hospitals), and supervised care facilities
This section also establishes the minimum allowed illuminance, equal to 1 footcandle measured on the floor (§1008.2.1). This requirement is lower in some assembly occupancies where desirable (e.g. movie theaters). This section also establishes a layer of redundancy for 24-hour hospital exit discharges, such that if any one lighting unit fails, the 1 footcandle illuminance is maintained.
§1008.3 Illumination Required: The power supply for means of egress illumination shall normally be provided by the premises’ electrical supply
While this section states that normal power can supply egress luminaires, it specifically calls our areas of a building where back-up power sources are required. This may mean your emergency lighting loads are on a dedicated electrical circuit with a back-up power supply or, as we see most often, local battery packs inside the luminaire. When the power supply fails, the emergency electrical system must automatically illuminate a variety of areas. The most obvious is the requirement that interior and exterior path of egress areas need to be illuminated, as must aisles, corridors, and exit ramps in large rooms requiring more than two exits (e.g. open offices and assembly areas). Areas that may require special access also must have emergency light – even though they’re not on the path of egress – including electrical equipment rooms, rooms associated with fire protection, generator rooms, and public restrooms >300 ft².
The emergency lighting systems requirements are also defined in this section:
- The system must be cable of providing 90 minutes of back-up power
- The system must provide 1 footcandle of illumination average, and no less than 0.1 footcandle, upon the initial loss of power.
- The system can’t depreciate by more than 40% throughout the 90-mnute period.
- The path of egress maximum illuminance level can’t be more than 40 times greater than the minimum illuminance level.
- 24-hour hospital facilities can’t have a single luminaire failure that drops the illumination level to less than 0.2 footcandles.
What about existing buildings?
Existing buildings get a little carve out in California Building Code. They’re expected to comply with the egress code that applied when at the time of construction in addition to the following requirement (that apply regardless of when the last permit was pulled):
- 1104.5: Means of egress lighting, where provided per the original construction code, must have emergency power for buildings with significant numbers occupants defined by the occupancy category. These systems need only provide 60 minutes of emergency power.
NFPA 101: Fire Life Safety Code
NFPA 101 is a different animal and a slightly more detailed document. Egress and emergency lighting requirements are covered in Chapter 7 section 8. (§7.8).
Like California, NFPA requires egress lighting on the path of egress; however, NFPA 101 is more comprehensive in terms of thinking about interactions between building systems:
- Lighting controls are permitted to shut off egress lighting when the space is unoccupied or when there is adequate daylighting.
- Lighting controls cannot have a dwell less than 15 minutes (§220.127.116.11.2 (3)).
- Lighting controls must turn on emergency lighting should the building fire alarm system (if present) be activated
- Lighting control devices cannot shut off power to emergency batteries or exit signs.
NFPA 101 §18.104.22.168 requires similar illuminance targets for general horizontal surfaces (1.0 footcandle minimum); however, the stair illuminance target is 10 footcandles when the stairwell is occupied. The 10 footcandle requirement is only necessary when normal power is present. On emergency power, the system needs 1.0 footcandle average, like all other egress path lighting systems.
NFPA 101 §22.214.171.124 expands the California’s one-luminaire failure criterion from only 24-hour hospital facilities to all occupancy types.
NFPA 101 §7.9 outlines emergency lighting requirements, many of which align with the California standards; although they go into specific detail about how these emergency lighting systems must be tested prior to installation and periodically after construction. Based on my work with commercial customers, I can say with certainty that very few operators comply with §7.9.3, which requires testing emergency lighting systems every 3 to 5 weeks to see if the batteries come on automatically, and annually to see if the batteries will last a full 90 minutes.
For existing buildings, NFPA 101 §39.2.7 describes egress lighting systems and §39.2.8 describes emergency lighting. Egress lighting must fully comply with §7.8; while emergency lighting only must comply where one of the criteria is true:
- The building is over 3 stories tall
- The building has 100 or more occupants above the level of exit discharge (e.g. typically ground-level).
- The building has over 1000 occupants.
Egress and Emergency Lighting in Practice
Compliance with egress and emergency lighting requires a little foresight. For example, in evaluating an exterior staircase that takes occupants from a building to the public way, we had to replace an existing lighting system that provided about 0.8 fc minimum with a lighting system that provided 10 fc minimum, to comply with NFPA 101. At the same time, this staircase only needed to provide 1 fc minimum during emergency lighting conditions. To provide some minimal energy savings to attribute to this project, we elected to add NFPA 101 compliant occupancy sensing controls. The biggest hurdle for this project was finding an occupancy sensor that could provide adequate coverage for the staircase entries while locating the sensor in an area where it wouldn’t be subject to errant jostling by the occupants.
Office buildings installed with nightlights in the corridors represent another great opportunity to both comply with modern codes and avoid excessive energy consumption. One of our projects involved installing energy-code compliant partial-off occupancy sensors in the corridors with differential scheduling (e.g. when unoccupied, dimming to 50% during the day and turning off overnight). This renders the nightlights redundant for egress purposes. For emergency lighting, we selected UL924-compliant battery packs for these luminaires and override the control signal during an emergency event. For more details on UL924, check out this great discussion over at The Lighting Controls Association.
We’re still working on picking the ideal solution for providing the routine testing and maintenance of the emergency lighting systems – including batteries and generators. As noted above, NFPA 101 requires building owners test their emergency lighting systems monthly and perform a full 90-minute test every year. In a single building with dedicated emergency circuits – this isn’t a significant amount of work. On a campus of 50 buildings with distributed emergency batteries located either on the wall or in the ceiling, that’s a lot of time to spend with ladders pushing buttons and making subsequent repairs. There are a few battery vendors moving into the centralized control space that will allow an operator to automatically test systems and report faults digitally, which reduces the labor significantly. We’ll soon be able to weigh in on whether the labor savings will be enough to justify the capital expense.
NFPA 101 is generally more stringent than California’s own building code. Federal facilities in California generally must comply with both standards. Lighting retrofitters and project developers must ensure their projects do not negatively impact the egress and emergency lighting systems. I’m fond of telling my clients, all the energy savings associated with a lighting retrofit will never recoup the liability costs from one safety-related incident. Thus, it’s incumbent on us as project developers to provide safe lighting retrofit solutions without sacrifices.