Why is the life span of an LED measured as lumen depreciation?

The life span of an LED is vastly longer than that of incandescent, fluorescent or HID light sources. LED are generally rated to last 50,000 hours or 100,000 hours. Although an LED never completely burns out the brightness of the light output by an LED diminishes over time. This diminution is known as "lumen depreciation" and the useable life span of an LED (in hours of operation) is measured by its lumen depreciation. The industry norm for calculating the life span of an LED is the point at which the LED reaches 30 percent lumen depreciation. A 100,000-hour rating is not equivalent to a lamp life rating. LED life is rated to a point where it has reached 30 percent lumen depreciation. At over 100,000 hours an LED would still be operating, but at a decreased lumen output.  more

The life span of an LED is vastly longer than that of incandescent, fluorescent or HID lamp sources, generally lasting 50,000 hours or longer. Although the LED never really burns out, product life span is measured by lumen depreciation and is typically stated to be when 70% of the original light output remains, shown as its L70 (L sub 70).  more

The life span of an LED is vastly longer than that of incandescent, fluorescent or HID lamp sources, generally lasting 50,000 hours or longer. As LEDs never really burn out, product life span is therefore measured by lumen depreciation. The Illuminating Engineering Society (IES) currently recommends calculating the life of an LED as the point at which the LED reaches 30 percent lumen depreciation. Remember, a 50,000-hour rating is not equivalent to lamp life rating. LED life is rated where it has reached 30 percent lumen depreciation. At 50,000 hours an LED would still be operating, but at a decreased lumen output.  more

The life span of an LED is vastly longer than that of incandescent, fluorescent or HID lamp sources, generally lasting 50,000 hours or longer. Although the LED never really burns out, product life span is measured by lumen depreciation.  more