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 www.ies.org/store. 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)