One of the most attractive features of LED lights is the fact that their lifespan is much longer than of incandescent, fluorescent or HID lamp sources and that they are much less prone to failure. This leads to amazing energy savings over the long life of their use.
However, even high quality LED lights will experience a reduction in brightness output levels) over a long period of time (over 50,000 of use).
Therefore lumen depreciation provides a more practical and effective way of measuring the useful life of an LED light – which is the point till which its light generation allows it to remain effective in real world usage scenarios.
Widely accepted international standards – recommended by the Illuminating Engineering Society (IES) – calculates the life of an LED as the point when the LED reaches 30 percent lumen depreciation. This means that the brightness falls by 30% to around 70% of its original levels.
In a practical scenario, If an LED fixture is lit for an average of 8 hours per day it will last over 17 years before needing replacement.