Lumen Maintenance Submission Guide

In the past, LED Lighting­ Facts did not include lumen maintenance as a verified performance metric because there was no industry standard for calculating it. In August 2011, the Illuminating Engineering Society published IES TM-21: Projecting Long Term Lumen Maintenance of LED Light Sources, which details a standard method for projecting LED light source lumen maintenance based on LM-80 data.[1] The publication of TM-21 enabled equitable projections of LED light source lumen maintenance for different products. In April 2012, LED Lighting Facts began allowing partners the option to claim an LED lumen maintenance percentage at 25,000 hours of operation at a given ambient test temperature, based on the combination of TM-21 projections and temperature measurements of the LED light source while operating inside the LED luminaire or replacement lamp.

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 50,000 hours and higher are possible. Given the risk of these high hourly values being misconstrued as lifetime claims, LED Lighting Facts decided to represent lumen maintenance at a fixed point in time—50,000, 36,000, 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.

Like the other optional metrics, LED lumen maintenance percentage will be displayed in the online approved product list; it may also be displayed on the LED Lighting Facts label if the partner chooses. During the label download process, partners will have the option to select a label that includes the claimed LED lumen maintenance. For more information on how to estimate lumen maintenance, see the Submission Process Reference Manual, located under the Library tab.

 

Supporting Documentation for LED Lumen Maintenance

To claim an LED lumen maintenance value for a product submission, a partner must upload the following supporting documentation for verification:

  • An ISTMT report in PDF form with ambient temperature (and LED drive current, if possible) included in the report.[2] See Section VI for laboratory policies for ISTMT.
  • LM-80 report in PDF form for each LED light source used in the lamp or luminaire. See Section VI for laboratory policies for LM-80 measurements.
  • Completed ENERGY STAR® TM-21 Calculator file in Microsoft Excel format.
    • Save the file, using the model number being submitted to LED Lighting Facts in the filename, before uploading with other supporting documentation.

The program defers to guidance published in September 2011 by ENERGY STAR regarding the content and application of LM-80 reports in support of submissions to LED Lighting Facts with the following exception:

  • Section 5.1.c; LED Lighting Facts will instead use the following guidance:
    • The same materials in the optical path after exiting epitaxial structures, with the exception of the phosphor.

The guidance is available on the ENERGY STAR website here

For detailed information on how to submit or update a product, please see the Submission Process Reference Manual, located under the Library tab.   

 

Claiming LED Lumen Maintenance for Products with Special Features

TM-21 does not provide a way of projecting LED lumen maintenance for products incorporating certain special features. LED Lighting Facts does not allow an LED lumen maintenance claim for certain products. Other products may include an LED lumen maintenance claim, but only under certain conditions. Partners must indicate if a product incorporates such special features using checkboxes provided in the product submission form.

Partners may not claim LED lumen maintenance for products with the following design elements:

  • Secondary optics with remote phosphors or other materials that could significantly affect the light output of the LED light source.

Some products incorporate remote phosphors that tune the color of the light emitted from the lamp or luminaire, but are physically separated from the LED light source. Because they are not integrated into the LED light source, their effect on performance is not included in TM-21 calculations. 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.” Because performance effects of such products are captured by LM-80 and TM-21, luminaire and lamp manufacturers using such LED light sources are permitted to claim an LED lumen maintenance value. Partners should direct any questions about eligible product designs to the LED Lighting Facts Team for clarification.

Partners may claim an LED lumen maintenance value for products with the following design elements, but with certain conditions:

  • Utilization of two or more unique LED light sources.

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. To obtain an accurate LED lumen maintenance claim for the combination of the light sources, the following conditions must be met and the following formula must be used:

  • Conditions
    • LM-80 data for each unique LED light source must be available and uploaded with the submission.
    • ISTMT temperature measurements for each unique LED light source must be available. All ISTMTs must be uploaded with the submission.
    • TM-21 calculations must be made at the same time (t) using the TM-21 Calculator Tool. A completed TM-21 Calculator Tool must be uploaded with calculations for each unique LED light source.
    • Nominal drive current of each unique light source within the luminaire must be known and detailed in the TM-21 Calculator Tool.
    • The following calculations are documented in an Excel file separate from the TM-21 Calculator Tool or in PDF form and uploaded with the submission.
  • Formula

Combined LED
Lumen Maintenance

=

[(N1 × LFi1 × YY1%) + (N2 × LFi2 × YY2%) + ⋯ + (Nn × LFin × YYn%)]

[(N1 × LFi1) + (N2 × LFi2) + ⋯ + (Nn × LFin)]

 

Where:

N = number of LED light sources in the lamp or luminaire

N1 for make/model 1, N2 for make/model 2, etc.

LFi = Initial luminous flux of LED light source

LFi1 for make/model 1, LFi2 for make/model 2, etc.

YY% = Lumen maintenance percentage of light source at time (t)

YY1% for make/model 1, YY2% for make/model 2, etc.

  • 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 product wattage and LED lumen maintenance. Without a methodology to project LED lumen maintenance accurately for such products, it must be clear that LED lumen maintenance claims are based on initial performance. When the variable LED drive current checkbox is marked, the following note will appear on the LED Lighting Facts label:

“Electronically controlled to maintain light output over time. Information based on initial test performance. Wattage may increase over time.”

  • Variable LED drive current for other purposes.

In addition to varying drive current over time to maintain light output, manufacturers may design their products with 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. The following note will appear when the variable wattage checkbox is marked:

“Information based on initial test performance. Wattage may increase over time.”

 

Claiming Lumen Maintenance in Family Submissions

 

A manufacturer who has become eligible to submit family groupings to LED Lighting Facts has several options for how they may 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 more details on family submissions including eligibility and submission requirements, please visit the Family Grouping Policies page.

For every family submission where the manufacturer wishes to claim lumen maintenance, the manufacturer will designate a Tested Lumen Maintenance (LM) Product.  The Tested LM Product is simply the product that was used in testing for the ISTMT.  Manufacturers will be asked to identify the Tested LM Product on the lumen maintenance tab upon submittal.

 

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.  In this case the Tested LM product is the Parent Model and manufacturers must provide supporting documentation based on the parent product.  Manufacturers will be able to identify this in the submission form on the lumen maintenance tab.

Please refer to the section above on supporting documentation for lumen maintenance.

 

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, they may do so by scaling the values off of the Tested LM Product.  The Tested LM Product does not have to be the same as the parent product as long as it is contained within the family submission. Again, the manufacturer will designate the Tested LM Product on the lumen maintenance tab in the submission form. 

In all cases where a manufacturer wishes to scale lumen maintenance values for related products in the family, a manufacturer must provide a methodology supporting the scaling method that is being used.  Manufacturers will be given the opportunity to provide this methodology upon submission.

Required documentation for the Tested LM Product must be submitted, including:

  • An LM-80 test report on the LED package/module/array from a laboratory listed on the LED Lighting Facts Approved Labs list
  • An LED package/module/array specification sheet
  • An ISTMT on the Tested LM product from a laboratory listed on the LED Lighting Facts Approved Labs list
  • A completed copy of the ENERGY STAR TM-21 Calculator
  • 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 LM 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 LM Product, including documentation of the methodology used to determine the lumen maintenance values listed for the related products within the subset.  Required documentation includes the following:

  • An LM-80 test report for the LED packages/modules/arrays for each subset from a laboratory listed on the LED Lighting Facts Approved Labs list
  • An LED package/module/array specification sheet for each subset
  • An ISTMT for each Tested LM Product from a laboratory listed on the LED Lighting Facts Approved Labs list
  • Completed copy of the ENERGY STAR TM-21 Calculator for each subset
  • 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 LM 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 certify that the Tested LM Product is the worst-case thermal performing product, and provide justification for the selection of the model in the submission form.

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 on how to submit products as a family, please see the Submission Process Reference Manual, located under the Library tab.

 

 

[1] Light source refers to an LED package, array, or module that is operated via an auxiliary driver. It does not refer to an LED die, an integral LED lamp, or luminaire. Definitions of LED package, array, and module can be found in ANSI/IESNA RP-16-10: Nomenclature and definitions for Illuminating Engineering.

[2] LED drive current in the luminaire or lamp may be up to 5% greater than the LM-80 drive current for the corresponding LM-80 case temperature.