Currently, the vast majority of lighting manufacturers operating in the European market use a specific "time [LxBy]" format to clearly label the service life of their LED lamps. For example, an LED lamp labeled L80B10 typically has a service life of 50,000 hours. While this nominal service life provides users with basic information about the actual operating life of an LED lamp, it has significant limitations and does not take into account potential failure risks that may occur during the lamp's lifetime. The components of this service life notation should be understood as follows:
First, the "time [hours]" component represents the estimated cumulative operating time required for the LED lamp to reach the specific parameter standards described by the subsequent Lx and By factors. This time period is a reference value calculated based on extensive experimental data and industry standards. Next, the "Lx" component represents the key metric of lumen maintenance. Its core function is to determine the percentage limit by which the luminous flux of an LED luminaire will decrease compared to its initial state at the end of a specified operating period. "x" represents this critical percentage.
Finally, the "By" component is defined as an overall factor. Its primary purpose is to specify the percentage of LED luminaires in the total installed base that are expected to fail to meet the Lx standard within the specified operating period. "y" corresponds to this overall percentage. For example, the symbol "50,000h L80B10" should be correctly understood as meaning that within the pre-determined 50,000-hour operating period, 10% of all installed LED luminaires of this model are expected to have their total luminous flux degrade to below 80% of their declared initial luminous flux value. This notation clearly reflects the distribution of luminous flux degradation over a specific period of time.
In the current LED lighting industry, the most common term is "average service life." Within this notation, the two key parameters—service life and lumen maintenance (Lx)—are defined and expressed based on an overall index (B50). For composite LED luminaires that integrate multiple LED chips or modules, the "50,000h L70B50" designation clearly states: The luminous flux of the LED luminaire is expected to be no less than 70% of its initial luminous flux value within the specified 50,000-hour operating life. Furthermore, 50% of all installed luminaires are expected to meet this luminous flux maintenance standard. This designation takes into account the lumen decay characteristics of multi-chip/module luminaires and their overall performance.
Average Light Source Lifespan
The "average lifespan" of a light source operating continuously under normal operating conditions consistent with industry standards is clearly defined. It refers to the cumulative time elapsed after 50% of all installed luminaires of this type fail. Simply put, it's the time it takes for a light source's failure rate to reach 50%. This metric is a crucial parameter for measuring the concentrated trends in the lifespan of a light source population and provides a key reference for users evaluating the overall lifespan of a light source.
Light Source Lifespan
In practical applications within the lighting industry, the term "service life" is actually a more popular and practical way of expressing "economic life." Professionally defined, it precisely refers to the period of time, after a light source has been put into normal operation, during which its luminous flux remains at least 80% of its initial luminous flux throughout its lifetime. This standard takes into account both the user's actual lighting needs and the economic efficiency of the light source. When the luminous flux of a light source falls below 80% of its initial value, its lighting performance often fails to meet the requirements of most scenarios and is generally considered to have reached the end of its service life.
