LED Reliability and Lumen Maintenance
What is Lumen Maintenance?
Lumen maintenance simply compares the amount of light produced from a light source or from a luminaire when it is brand new to the amount of light output at a specific time in the future. For instance, if a luminaire produced 1000 lumens of light when it was brand new and now produces 700 lumens of light after 30,000 hours, then it would have lumen maintenance of 70% at 30,000 hours. Sometimes this is stated as lumen depreciation, which in our example would be 30% lumen depreciation from the original light output. Lumen maintenance is often specified as L50, L70, L80, or L90. In each case, L stands for lumen maintenance and the number is the percentage of light output remaining.
The appropriate lumen maintenance target is usually based on the application and the requirements set forth by customers. Since the human eye generally can’t detect a change in light output until there has been 30% depreciation, L70 is often established as the target for an application. With LUXEON LEDs, it generally takes tens of thousands of hours before the LUXEON LED will lose 30% of its initial light output.
Philips Lumileds technical advances in all areas have led to the industries longest lived, most reliable LEDs. LUXEON LEDs meet the LM-80 test criteria developed by the Illumination Engineering Society and the Department of Energy Solid State Lighting Standards Development group by a wide margin. Luminaire and lamp manufactures that use LUXEON LEDs can achieve Energy Star certification and ensure their products perform as promised.
Lumen maintenance and lifetime are intertwined
Applying Lumen Maintenance Information
Philips Lumileds has collected more lumen maintenance data than any other power LED manufacturer and continues to run tests on new and existing products. As a provider of LEDs to the lighting, automotive and consumer electronics industry it’s essential that we understand and characterize our lumen maintenance performance.
In the illumination industry, IES LM-80 is the standard that describes how lumen maintenance testing should be conducted for LEDs and how the LM-80 report should be formatted. Philips Lumileds has started to publish its LM-80 test reports so that everyone can see what the data looks like and become more familiar with this important subject.
Luminaire manufacturers use this data as part of their submission to the ENERGY STAR program and to extrapolate how the LUXEON LEDs will perform in their application so they confidently bring their products to market.
To learn more about lumen maintenance and the LM-80 test report visit the Lumen Maintenance page.