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ANSI/IES LM-80-21
Approved Method: Measuring Maintenance of Light Output Characteristics of Solid-State Light Sources
LEDs typically exhibit very long operational life characteristics and, depending on drive current and use conditions, can be in use for 50,000 hours or longer. The light output from LEDs slowly decreases over time. This characteristic of declining output without sudden and permanent failure creates a risk that an LED-based lighting product near end of life may be operating but performing outside the product’s specification, or outside required codes, standard practices, or regulations. LEDs may also undergo gradual shifts in the emitted spectrum over time that may result in unacceptable appearance or color rendering, or degraded efficacy. This document provides the methods for measurement of luminous flux and color maintenance for LED packages, arrays, and modules. It covers luminous, radiant, or photon flux maintenance and color maintenance, including changes in chromaticity coordinates, peak wavelength, or centroid wavelength versus time. The maintenance characteristics are measured under controlled conditions that allow direct comparison of results obtained at different laboratories.
Illuminating Engineering Society of North America [iesna]