IES Publishes TM21-11, Useful Lifetime of LEDs

The Illuminating Engineering Society of North America (IES) announces a new document,Projecting Long Term Lumen Maintenance of LED Light Sources (TM-21-11).

The document recommends a method for projecting the lumen maintenance of LED light sources from the data obtained by the procedures found in IES document Approved Method for Measuring Lumen Maintenance of LED Light Sources (LM-80-08).

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, which can vary from manufacturer to manufacturer and between different LED package types produced by a single manufacturer. 

Projecting Long Term Lumen Maintenance of LED Light Sources (TM-21-11) is available on the IES website at Phone orders can be directed to 212-248-5000, ext 112. (25 Pages, 8 ½ X 11 Trim Size, Softcover, ISBN: 978-0-87995-259-4, $40.00 List Price, $28.00 IES Member Price) 

IES is the oldest and largest educational and scientific society in North America devoted to lighting. Since 1906, the IES has sought to improve the lighted environment by bringing together those with lighting knowledge and by translating that knowledge into actions that benefit the public. A broad variety of programs, including publications, conferences and seminars, have been established to accomplish this mission. IES publishes and distributes the finest lighting literature authored by committees with the most experienced minds in industry and academia today. For more information about IES, go to