Frequently Asked Questions:
Optional Label Metrics
What is an optional label metric?
Manufacturers have the option of submitting lumen maintenance and warranty information during the submission process. These data metrics can then be displayed on the LED Lighting Facts label. But unlike the five required metrics (lumens, watts, efficacy, CRI and CCT), the manufacturer is not required to submit this information.
Why is the warranty claim limited to “yes” or “no” instead of the number of years?
Rather than provide the warranty period in years, the LED Lighting Facts label will only state if a warranty is available to provide a more consistent comparison across products and manufacturers. For example, two products with 5-year warranties may in reality be quite different because of different components covered or other warranty terms that are inconsistent. For products with a “yes” designation for warranty, LED Lighting Facts has added the ability to link to the manufacturer’s warranty information directly from the LED Lighting Facts Products List.
Is the lumen maintenance percentage a lifetime metric?
No. The optional percentage listed on the LED Lighting Facts label describes the lumen maintenance (the amount of light remaining after a specified time, compared to the initial output) of the LED light source while operating in the thermal environment of the lamp or luminaire. SSL lifetime and reliability, by contrast, take into account the performance of other system components over time, including electronics (e.g. the power supply or driver), optics (e.g. lenses and reflectors), thermal management system, housing, and related components.
There is no industry standard method for measuring or estimating the lifetime and/or reliability of SSL products, taking the entire system into account, though some manufacturers have their own methods for doing so. LED Lighting Facts uses industry standard test procedures whenever possible to ensure apples-to-apples comparisons of product performance.
Why not list an actual lifetime?
TM-21 focuses on a specific light source component (package, module, array) while operating in the thermal environment of the lamp or luminaire, but doesn’t take into account the performance of the entire luminaire or lamp. A complete luminaire is a complex system, with many components that can affect lifetime, such as the driver, optics, thermal management, and housing. The failure of any one of these can mean the end of the luminaire's useful life, even if the light source is still functioning. There is not yet a standard test to determine SSL system lifetime, so in the meantime, estimating the light source lumen maintenance with the TM-21 standard is the most reliable approach.
Why isn’t the lumen maintenance being reported using L70 terms?
L70 is a useful metric for estimating when an LED will no longer produce acceptable light levels. It was relatively common in the early years of the LED general illumination market to use L70 values for the LED light source a proxy for the lifetime of the complete LED luminaire or replacement lamp. Such use of this performance data has the potential to mislead stakeholders, because there is not yet an industry standard method for estimating LED luminaire or replacement lamp lumen maintenance or lifetime. While some manufacturers may have robust engineering data to support their claims, others may not, and LED Lighting Facts cannot evaluate lumen maintenance or lifetime of an LED luminaire or replacement lamp without an industry standard method. LED light source lumen maintenance is only one factor affecting LED luminaire and replacement lamp lifetime. The driver, other electronics, optics, and thermal and mechanical components of an LED product can all fail or degrade over time, and a robust lifetime or reliability analysis must consider them all. TM-21 introduces provisions to limit L70 values based on the amount of LM-80 data collected (more data available means a higher value can be claimed), but even so, values of 36,000 hours and higher are possible. Given the risk of these high hourly values being misconstrued as lifetime claims, LED Lighting Facts, in cooperation with DOE’s Reliability and Lifetime Working Group, decided to represent lumen maintenance at a fixed point in time–25,000, 15,000, or 10,000 hours, at the option of the manufacturer. Instead of projecting at what point in time the product will reach a given percentage of initial output, as L70 does for a fixed 70% lumen maintenance level, this metric represents the percentage of initial output projected to be reached at a fixed point in time.
Will all manufacturers be required to list lumen maintenance and warranty on the label?
No. Both the proposed lumen maintenance and warranty information are completely optional. Manufacturers would have the option of downloading and presenting four versions of the LED Lighting Facts label. The label could include the following information:
1) Current and required label metrics
2) Current and required label metrics + Warranty
3) Current and required label metrics + LED Lumen Maintenance
4) Current and required label metrics + LED Lumen Maintenance + Warranty
What are the differences between LM-79, LM-80, and TM-21?
It is important to understand the difference between these three standards because they are all used to determine the performance metrics on the label, including the optional lumen maintenance metric.
LM-79 is an approved method for taking electrical and photometric measurements of SSL products. It covers total flux (light output), electrical power, efficacy, chromaticity, and intensity distribution. The five required metrics on the LED Lighting Facts label come from LM-79 test results.
LM-80 is an approved method for measuring the lumen maintenance of LED packages, arrays, and modules (i.e., the LED light source) at various temperatures. It specifies a minimum testing period of 6,000 hours, although 10,000 hours is preferred, and it requires testing at a minimum of 1,000-hour increments. LM-80 provides no determination or estimate of expected life or lumen maintenance beyond the test data, which, even with 10,000 hours of testing, falls far short of the claimed lifetimes of most SSL products on the market today.
TM-21 provides guidelines for using LM-80 data to estimate the light source lumen maintenance beyond the LM-80 test period. LM-80 and TM-21 are designed to work hand-in-hand, with TM-21 using the LM-80 data, along with in-situ temperature performance data, to project the lumen maintenance of an LED light source.
How does this new metric relate to requirements for ENERGY STAR?
While LED Lighting Facts would be the first program to specifically list the lumen maintenance at 25,000 hours, that metric is derived from TM-21, LM-80, and in-situ temperature measurements, which is the same combination of testing and projections used by ENERGY STAR. The new LED Lighting Facts metric can be translated into an L70 value relatively quickly, which could then be used by other qualification programs.
Why isn’t there an option to claim lumen maintenance values at times longer than 25,000 hours?
In developing this new metric, LED Lighting Facts and the DOE SSL Reliability and Lifetime Working Group worked to avoid the implication that long lumen maintenance times translated directly to long lifetimes of the complete lamp or luminaire. Long lumen maintenance times, which are commonly quoted up to 50,000 hours, have still not been verified through rigorous lifetime and reliability testing.
What about products with special features – can the lumen maintenance be submitted?
Following are several product features that can affect lumen maintenance, and LED Lighting Facts policies on those products:
Products with variable LED drive current to maintain light output over time:
Some products incorporate electronic controls that adjust the LED drive current during long term operation to maintain light output near initial performance levels. This product design will affect the LED lumen maintenance. Manufacturers submitting products with variable drive current controls may claim LED lumen maintenance, but without a standard methodology for accurately projecting LED lumen maintenance as the drive current is adjusted over time, it must be clear that LED lumen maintenance claims are based on initial performance. Partners must indicate that the product incorporates variable drive current controls on the submission form by marking the appropriate checkbox. When this box is checked, a note will appear on the label that the product includes electronic controls to maintain light output over time, that LED lumen maintenance claims are based on initial performance, and that wattage may increase over time.
Products with variable LED drive current for other purposes:
In addition to varying the drive current over time to maintain light output, some products may incorporate controls that affect other performance attributes, such as color in products with multiple LED light sources. In such cases, the LED lumen maintenance may be affected by the electronic controls. Manufacturers submitting products with controls to vary the wattage for purposes other than maintaining light output may claim LED lumen maintenance, but without a standard methodology for accurately projecting LED lumen maintenance for such products over time, it must be clear that LED lumen maintenance claims are based on initial performance.
Partners must indicate that the product incorporates variable wattage controls on the submission form by marking the appropriate checkbox. When this box is checked, a note will appear on the label that the label information is based on initial performance and the wattage may change over time.
Products with multiple LED light source types:
Some products incorporate two or more unique LED light sources to achieve desired light levels or color that cannot be attained by a single type of light source alone. These multiple light sources will likely exhibit different lumen maintenance performance. Partners may still claim LED lumen maintenance, but must use a formula provided in Product Submission and Testing Requirements to obtain an accurate lumen maintenance claim for the combination of the LED light sources’ lumen maintenance. Partners must indicate that the product incorporates multiple LED light sources by marking the appropriate checkbox in the product submission form and upload LM-80 data for each light source, ISTMT data with temperature measurements for each light source, and a saved copy of the completed ENERGY STAR TM-21 Calculator in a Microsoft Excel file format for each light source.
Products with remote phosphors:
Some products incorporate remote phosphors that tune the color of the light emitted from the lamp or luminaire, but that are physically separated from the LED light source. Since they are not integrated into the LED light source, their effect on performance is not included in the new TM-21-based metric. Partners are thus not permitted to claim LED lumen maintenance for products employing remote phosphors.
Please note that some LED light source manufacturers may use similar features within the light source that may still be termed “remote phosphors.” Since performance effects of such products are captured by LM-80 and TM-21, luminaire and lamp manufacturers using such LED light sources are still permitted to claim an LED lumen maintenance value. Partners should direct any questions about allowable product designs to the LED Lighting Facts Team for clarification.
Can lumen maintenance be claimed if products are submitted as a family?
A manufacturer who has become eligible to submit family groupings to LED Lighting Facts has several options for how they claim lumen maintenance. These options are unique to family groupings, so manufacturers are encouraged to become familiar with the policies surrounding family groupings before proceeding. For every family submission where the manufacturer wishes to claim lumen maintenance, the manufacturer will designate a "tested" Lumen Maintenance product. The "tested" lumen maintenance product is simply the product that was used for the ISTMT. Manufacturers will be asked to identify the "tested" lumen maintenance product on the lumen maintenance tab.
Option 1: Lumen Maintenance for the Parent Product Only
A manufacturer may claim lumen maintenance for the parent product only, without having values claimed for the other related products within the family. Lumen maintenance should be treated as if it were a single submission, and manufacturers must provide supporting documentation based on the tested parent product.
In this case the "tested" lumen maintenance product is the Parent Model, for which the manufacturer will indicate in the submission form on the lumen maintenance tab.
Option 2: Lumen Maintenance for the Parent and Related Products
If a manufacturer wishes to enter lumen maintenance claims for all products within a family, the values can be scaled, provided that a methodology supporting the scaling method is submitted.
A "tested" lumen maintenance product in the family must be designated, from which the calculations will be based. The "tested" lumen maintenance product may be different from the tested parent product, however it must still be included in the family group upon submission, represented by rated performance claims.
Required documentation for the tested LM product must be submitted and include documentation of the methodology used to determine lumen maintenance values for related family products.
Different LED chips/modules/arrays within a family
In the case where a family contains products with different LED chips/modules/arrays, a “tested" lumen maintenance family product must be designated for EACH unique LM-80 dataset used in the family. These groupings are treated and evaluated as subsets of the family. Required documentation must be submitted for EACH "tested" lumen maintenance product, including documentation of the methodology used to determine the lumen maintenance values listed for the related products within the subset:
- LM-80 test report on LED package/module/array from a laboratory listed on the LED Lighting Facts Approved Labs list
- LED package/module/array specification sheet
- ISTMT on tested lumen maintenance products from a laboratory listed on the LED Lighting Facts Approved Labs list
- Completed copy of the ENERGY STAR TM-21 Calculator
- Documentation for methodology used to determine lumen maintenance values for the subset of related products using the same LM-80 dataset.
Worst-Case Lumen Maintenance
If the "tested" lumen maintenance product represents a worst-case lumen maintenance condition for the product family or subset of related product family members in the case of multiple LED chips, the manufacturer may choose to list the same worst case lumen maintenance percentage for all related products in the family or subset (without scaling). Typically, the worst-case lumen maintenance condition is the product with the hottest thermal environment for the LED. The manufacturer must provide justification for the selection of the model that represents the worst-case lumen maintenance condition.
Alternatively, if justification can be provided showing that there is no change in thermal conditions in the products of the family group, thus proving that no worst-case product exists, the manufacturer may list the same lumen maintenance percentage for all related products in the family.
For more information, please see the Family Grouping Policies located under the About tab.
Why doesn’t the label include information on color shift and replaceable parts?
There are no standard test procedures for color shift and no standard definition on what are replaceable parts for SSL luminaires and lamps. The LED Lighting Facts program strives to provide data that can be substantiated by industry approved testing methods, whenever possible.