LLMF = Lamp Lumen Maintenance Factor L70 = 0,7 L80 = 0,8 L90= 0,9
One of the benefits of the LED , they have no filaments that may break, LED's can have long lifetime.
The light output from LED it slowly dims down over time.
The amount of light from the light source at a specific time in the future is referred to as the lamp lumen maintenance factor ( LLMF )
The lifetime of a LED module is defined as the time it takes until its light output, or lumen maintenance, reaches 70% of the initial output.
This is also called L70. In other words,
The luminaire standardised LED lifetime to L70 = 50000 hours, which corresponds to an LLMF of 0,7 as long as the lifetime of the lighting installation is set to the same amount of hours.