Estimating LED Life
Early 21st century claims purported LED lighting to last 100,000 hours. The problem with this claim was it simply wasn’t true under realistic conditions. A single, bare LED might last that long, but once integrated into a lighting system, the LRC showed that LED life could be far less. LED life estimation, especially lighting system life, is complicated by matters of integration with other components, including optics and housing; installation into less than ideal environments, such as recessed luminaires in insulated plenums; and a lack of appropriate measurement methods.
Long-term life-testing research led to the understanding that heat negatively affects LED life, and that there are many ways in which LEDs might be exposed to high heat. In turn, this led to research to develop methods of estimating the junction temperature of LEDs. Further studies explored how the environment impacts heat and system life, leading to application-based test methods.
Through its Alliance for Solid-State Illumination Systems and Technologies (ASSIST), in 2005 the LRC published the first document in the ASSIST recommends series, a recommended test method for estimating LED life for general lighting. ASSIST recommends: LED Life for General Lighting became the basis for LM-80, the approved LED life testing method of the Illuminating Engineering Society, published in 2008.
Since developing the ASSIST life-test method, the LRC has continued to investigate system life issues through studies of:
Technical Reports and Publications
ASSIST. 2005, 2007. ASSIST recommends: LED Life for General Lighting. Vol. 1, Iss. 1-7. Troy, N.Y.: Lighting Research Center.
Han, L., and N. Narendran. 2009. Developing an accelerated life test method for LED drivers. Ninth International Conference on Solid State Lighting, August 3-5, 2009, San Diego, Proceedings of SPIE 7422: 742209.
Full-text PDF 
Narendran, N., Y. Gu, L. Jayasinghe, J.P. Freyssinier, and Y. Zhu. 2007. Long-term performance of white LEDs and systems. Proceeding of First International Conference on White LEDs and Solid State Lighting, Tokyo, Japan, November 26-30, 2007, P174–P179.
Full-text PDF
Narendran, N. and Y. Gu. 2005. Life of LED-based white light sources. IEEE/OSA Journal of Display Technology 1(1): 167-171.
Full-text PDF
Gu, Y., N. Narendran, and J.P. Freyssinier. 2004. White LED performance. Fourth International Conference on Solid State Lighting, Proceedings of SPIE 5530, eds. I.T. Ferguson, N. Narendran, S.P. DenBaars, J.C. Carrano, 119-124. Bellingham, WA: International Society of Optical Engineers.
Full-text PDF
Hong, E., and N. Narendran. 2004. A method for projecting useful life of LED lighting systems. Third International Conference on Solid State Lighting, Proceedings of SPIE 5187: 93-99.
Summary | Full-text PDF
Narendran, N., L. Deng, R.M. Pysar, Y. Gu, and H. Yu. 2004. Performance characteristics of high-power light-emitting diodes. Third International Conference on Solid State Lighting, Proceedings of SPIE 5187: 267-275.
Summary | Full-text PDF
Narendran, N., Y. Gu, J.P. Freyssinier, H. Yu, and L. Deng. 2004. Solid-state lighting: Failure analysis of white LEDs. Journal of Crystal Growth 268 (3-4): 449-456.
Full-text PDF
Project Summary Sheets
Accelerated Life-test Method for LED Drivers (2009)
ASSIST recommends… Directional Lighting (2007)
ASSIST recommends: LED Life for General Lighting (2005)
Benchmarking High-Power LEDS: A Life Test (2004)
Media Coverage
How to Measure the Lifespan of White LEDs – Smarthouse, April 2008
Standards for LEDs – Lighting Design Lab Newsletter, Winter 2006
Industry alliance proposes standard definition for LED life – LEDs Magazine, April 2005
Sponsors
ASSIST
United States Department of Energy, Cooperative Agreement No. DE-FC26-01NT41203
University of California at Santa Barbara
|
