(Issue: May 2021 )

NALMCO Sponsors Maintenance Study

By Craig DiLouie, CLCP, LC

Join Norma Frank as she discusses the emergency lighting study on Wed., Oct. 13, during the Annual Convention & Trade Show. See program information in the May 2021 LM&M issue or online, www.NALMCO.org

NALMCO and Colorado Lighting, Inc. are sponsoring a new study conducted by the Icahn School of Medicine at Mt. Sinai in New York City and principally funded by the Jim H. McClung Lighting Research Foundation. The one-year study aims to determine if older LED exit signs suffering significant lumen depreciation but still operating produce sufficient brightness for life/safety goals. The results may have a substantial impact on how LED exit signs are evaluated, potentially offering customer engagement opportunities for lighting management companies.

One of the earliest major adoption points for LEDs was exit signs, taking advantage of their extraordinary efficiency as an indicator. As early as the 1990s, LED retrofit kits and exit signs entered the market to challenge incandescent and compact fluorescent light sources. Due to their advantages—energy efficiency, long service life, design flexibility, greater ruggedness, and ability to produce red or green light without a filter—LEDs became the predominant source over time.

The rapid adoption of LEDs produced a challenge, however, which was the possibility of mortality expressed as lumen depreciation. While lumen maintenance of direct red LEDs is generally good, performance can vary across products and LED power levels. An LED with an L70 projected lifetime of 30,000 hours can “fail” after less than four years based on continual operation. With an L70 of 50,000 hours, “failure” may occur in less than six years.

Why is this a problem? After all, traditional light sources offer a rated life of 2,000 to 10,000 hours. These sources typically exhibit a clear mortality mode, however; the lamp fails to light and requires replacement. In the case of an LED exit sign, the luminaire may be visually operational but no longer producing sufficient photometric brightness as to be visible during emergency (smoky) conditions. Various standards require that exit signs produce a minimum brightness when the exit signs are newly installed and state that output can degrade over time. Otherwise, there are not widely adopted, consistent practices to evaluate existing exit signs other than periodically confirming they are On.

After forming a hypothesis that a substantial portion of currently installed LED exit signs may be operating but no longer producing sufficient brightness for life/safety goals, Colorado Lighting’s Norma Frank, CLMC, submitted a proposal to the Jim H. McClung Lighting Research Foundation to fund a study conducted by the Icahn School of Medicine at Mt. Sinai, the new professional residence of Dr. Mariana Figueiro, formerly director of the Lighting Research Center. The study was approved in late 2020 and was expected to take 12 months to complete. NALMCO and Colorado Lighting are sponsors.

The goals of the study are to develop a field-based testing method to measure average exit sign brightness, validate the method with field measurements, identify any relationship between age and average brightness, and gain insight regarding the incidence of exit signs no longer satisfying minimum brightness requirements.

Specific tasks to be completed by the research team include:

Literature review: The researchers will review all existing studies related to factors that make luminous signage detectable, identifiable and legible. The review will validate criteria for brightness, uniformity and contrast under critical conditions. Best practices, specification guide and related standards will be reviewed. This task will produce photometric criteria against which field measurements can be compared.

Concurrently, the researchers will interview experts to identify industry priorities and common practice for selecting, installing and maintaining exit signs. The National Fire Protection Association (NFPA) and the Fire Protection Research Foundation (FPRF) will be invited to contribute information about key issues related to the use of exit signs under emergency situations.

Field measurement procedure: The researchers will acquire several types of green and red exit signs and evaluate a range of methods to test sign brightness. These may include spot measurements at the sign using a portable luminance meter or digital imaging and also measurements at a known distance. These methods will be compared for simplicity, repeatability, accuracy, and cost. This task will produce a procedure for measuring exit signs in the field.

Field measurements: The researchers will conduct field measurements of exit signs installed in buildings in at least two locations. As much information as possible about exit sign operating age will be documented. The measurements will target about 100 to 120 signs, focusing on panel-face signs using red or green LEDs. This task will produce a large set of data with which to test the hypothesis.

Technical analysis: The researchers will estimate the number of exit signs with potentially insufficient brightness and relate that to the age of the sign. This is the ultimate test of the hypothesis that the greater proportion of older exit signs will have insufficient brightness. If the hypothesis is confirmed, the researchers will compare expected and actual lumen depreciation. If the hypothesis is not confirmed, the researchers hope to gain an estimate of the portion of exit signs that produce insufficient brightness, regardless of age.

Present the results: The researchers will host a roundtable of relevant stakeholders, including NALMCO, to share project findings and discuss next steps. These may include: including field measurements in exit sign evaluation programs, potential changes to existing standards, and education of building owners regarding if, how, and when to evaluate exit signs. A report will be produced.

The researchers anticipate that this will be an initial study to develop a field measurement method and test the hypothesis. They expect the results will support a larger study that will include more applications and locations. The ultimate goal is to get a handle on the scope of the problem should it exist and produce actionable guidance for maintenance and replacement of exit signs.

This is a significant study in the industry, as it could result in revision of lighting maintenance practices, possibly affect future development of life/safety codes, and produce opportunities for lighting management companies.

Craig DiLouie, CLCP, LC, principal of ZING Communications, Inc., is a consultant, analyst and reporter specializing in the lighting and electrical industries, and a regular contributor to LM&M. You may contact Craig at cdilouie@zinginc.com.