In architectural lighting, lifetime is about more than just how long a luminaire works. It defines the visual consistency of your project, reduces maintenance costs, and supports long-term reliability.
Unlike traditional lamps, LEDs rarely fail overnight. Instead, their light output declines gradually. That’s why lifetime is expressed with two key parameters: L and B.
L: Lumen maintenance.
The L value tells you how much of the initial luminous flux the LED still delivers after a given number of operating hours.
- L80 means 80% of the original light output is maintained.
- L90 would mean 90% is maintained — often preferred for demanding retail or gallery work.
B: Statistical performance.
The B value indicates the percentage of luminaires that may drop below the stated L level due to normal variations in production, ageing, or environmental factors.
For example: 50,000 h L80B20 means:
- After 50,000 operating hours, 80% of the initial luminous flux is maintained.
- Up to 20% of the luminaires may deliver less than that 80% level.
Importantly, this B value does not mean complete failure — it’s a statistical forecast of reduced output in a fraction of the units.
A real-world example.
Our Caro track spotlight typically reaches 50,000 h L80B20. This means:
- After 50,000 operating hours, 80% of the initial luminous flux is maintained.
- Up to 20% of the luminaires may deliver less than that 80% level
This is a level of performance that ensures reliable, consistent light quality in professional retail, hospitality, and gallery environments.
Testing and prediction standards.
At Karizma Luce, all our LEDs are tested according to the internationally recognised LM-80 standard, which measures lumen maintenance under controlled conditions.
To predict long-term performance, we apply the TM-21 calculation method — the IES-recommended method for predicting how light output declines over time based on LM-80 test data.These lifetime specifications are always listed in each product’s datasheet.
Why it matters.
Clear lifetime information reflects technical transparency and lets designers predict how their projects will look years from now — supporting quality, efficiency, and trust.
Led’s delight!
