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February 01, 2015
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  • Projecting Long Term Lumen Maintenance of LED Light Sources + Addendum A
    Projecting Long Term Lumen Maintenance of LED Light Sources + Addendum A
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    2011 – 25 pages
    8 ½ X 11  Softcover
    ISBN: 978-0-87995-259-4
    List Price: $40
    IES Member Price: $28.00
    Order # TM-21-11

    Product ID: TM-21-11
    Price: $40.00
    Member Price: $28.00
    Product Detailed Description
    This document recommends a method for projecting the lumen maintenance of LED light sources from the data obtained by the procedures found in IES document LM-80-08 Approved Method for Measuring Lumen Maintenance of LED Light Sources.

    LED light sources provide a very long usable life but light output gradually depreciates over time.  TM-21-11 provides the method for determining when the “useful lifetime” of an LED is reached, a point when the light emitted from an LED depreciates to a level where it is no longer considered adequate for a specific application.  Lumen maintenance of LEDs can vary from manufacturer to manufacturer and between different LED package types produced by a single manufacturer.

    Normative References
    Test Data and Sample Size
    Lumen Maintenance Life Projection
    Temperature Data Interpolation
    Annex A Rationale for the Recommended Data Extrapolation
    Annex B Sample Size Selection for Data Extrapolation
    Annex C Least Squares Formula
    Annex D Limit for Duration of Prediction
    Annex E Data Test Set for Validation of Calculation – Examples
    Annex F Consideration of Manufacturer’s Prediction Model
    Annex G Analysis of Mathematical Modeling as a Method of Projecting Lumen Maintenance Life
    Informative References

    Addendum A for TM-21-11: Projecting Long Term Lumen Maintenance of LED Packages

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