Abstract
LED lighting and smart controlling can decrease the consumption of electric power in zero or positive energy buildings. This study demonstrates that cyclic dimming, which appears in smart controlling, e.g. through occupancy sensing, might have an effect on the luminaire lifetimes and failure rates. Two different types of LED luminaires were aged in 30-s cycled dimming and undimmed modes. The manufacturer-specified lifetimes for both luminaire types were 100 000 hours. For one of the luminaire types, four out of five cycled units failed before 30 000 operating hours. For the uncycled luminaires, the lifetimes estimated from the measurements were over 100 000 hours. For the other type, the estimated lifetimes were 75 000 hours and 64 000 hours for uncycled and cycled luminaires, respectively.
Highlights
The energy savings due to LED lighting products are remarkable when compared to the traditional incandescent and fluorescent lighting, making the LED products attractive in zero or positive energy buildings
This study demonstrates that cyclic dimming, which appears in smart controlling, e.g. through occupancy sensing, might have an effect on the luminaire lifetimes and failure rates
In the results after 15 000 h, one can see that the luminous fluxes of the cycle dimmed luminaires are lower than those of the undimmed luminaires, indicating that the cycled dimming has a negative effect on the luminous flux
Summary
The energy savings due to LED lighting products are remarkable when compared to the traditional incandescent and fluorescent lighting, making the LED products attractive in zero or positive energy buildings. Cyclic dimming, which appears in smart controlling, effectively decreases the driving current of the LED chips which should result in extended lifetime. The smart lighting control may cycle the temperatures of the components of the system, introducing additional stress to the LED components and the driving electronics of the luminaires as compared to the traditional controlling, which may accelerate the ageing of the luminaire.
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