Lumen maintenance is a measure of the amount of light produced from a light source or luminaire when it is brand new as compared to the light output at a specific time in the future. Until now, lumen maintenance was often specified as L50, L70, L80, L90; or LM50, LM70, LM80 or LM90; with L or LM both standing for lumen maintenance and the number specifying the percentage of light output remaining. For instance, LM70 or L70 at 50,000 hours means the light source or luminaire maintains 70% of the light output after 50,000 hours.
This nomenclature is now beginning to change. What happens when a luminaire reaches LM70 at 270,000 hours? Does the specification matter? It may not if the specific luminaire based on application will only be used until LM80. If lumen maintenance is used to compare two products, it is difficult to compare an LM70 at 30,000 hours to an LM80 product at 25,000 hours.
The usable life of LEDs in luminaires is increasing and in many instances now exceeds 100,000 hours. This is creating a new measure, specifying the lumen maintenance at 100,000 hours. For example LM84 at 100,000 hours informs the person investing the product that the LEDs will maintain 84% of the lumen output at 100,000 hours.
An example is a new LED instant restrike sports lighter luminaire. The sports lighter luminaire emits 75,000 lumens and is LM88 at 100,000 hours and is LM70 at 270,000 hours. LM88 at 100,000 hours is a more accurate measure because in this application it is unlikely the luminaire would be used below LM80. And 100,000 hours from now, it will probably be replaced by more efficient technology whether it functions or not.
Contact an Access Fixtures lighting specialist to learn more about lumen maintenance.