Oct 11, 2018

Issued October 9, 2018

IES LM-80 and TM-21 are powerful tools that allow the lighting community to evaluate, compare, and select reliable LED components. LED components are combined with luminaire housing, optics, and drive circuity to form a complete luminaire. The reliability of the complete luminaire depends on many failure mechanisms beyond the LED component level, including drive circuitry and any secondary optical components. Other testing standards focus on these degradation mechanisms; they should also be used for determining the complete luminaire lifetime.

Inconsistent LED product lifetime marketing claims made by some manufacturers have led to questions about the IES methods widely used to characterize luminous flux and color maintenance for the LED components within: ANSI/IES LM-80-15 (“LM-80”), IES Approved Method for Measuring Luminous Flux and Color Maintenance of LED Packages, Arrays and Modules, and IES TM-21-11 (“TM-21”), Projecting Long Term Lumen Maintenance of LED Light Sources. Very often these claims are based on violations of TM-21’s ‘6X rule’.

The gradual decline LED components exhibit motivated the IES to develop the LM-80 test method and the TM-21 modelling and projection method. The Testing Procedures Committee realized its models were limited in their ability to predict future performance. The Committee therefore limited projections to 6 times the duration of the collected LM-80 data. This limit ensures that projections don’t exceed the model’s statistical confidence levels.

For example, when TM-21 results are used correctly, projections using 10,000 hours of LM-80 data shall never exceed 60,000 hours. In this instance, a marketing claim of 100,000 hours to L70 would not be supported by IES standards. TM-21 Addendum B (which replaced Addendum A) explicitly disallows reporting of such projections. See Errata & Addenda.

Further, it is inaccurate to make marketing claims regarding the lifetime of an entire luminaire using only TM-21 projections, as this method only applies to the LED components within.

The IES does not support the use of marketing claims exceeding TM-21’s 6X extrapolation limit. Marketing claims leveraging values beyond this 6X limit are misleading and not supported by IES standards.

The IES does not support the use of LED lumen maintenance life as the sole metric for determining solid-state luminaire lifetimes.