Aug 18, 2017: In designing lighting products, maintenance factor had always played a significant role. However, with the introduction of LED lighting, manufacturers now claim better performance of their luminaires, and ignore the maintenance factor altogether. The LED lighting manufacturers argue that the traditional factors that make up maintenance factor cannot apply to a light source like LEDs, which have extended lifespan.
Calculating maintenance factor
The standard for calculating maintenance factor is given in document BS EN 12464-1 ‘Light and Lighting – Lighting of work places’, where lighting requirements for people in indoor work places are specified. The figure should be calculated for ‘the selected lighting equipment, environment and schedule’, according to maintenance factor.
In today’s scenario, a MF of 0.8 may sound reasonable as most can imagine a lighting installation losing 20% of its illuminance over time. However, 40% is simply unacceptable. This is where LED came into and opened the lead-lined box known as maintenance factor.
LED manufacturers claim that since there are no lamps to change, there is no issue related to maintenance factor. Environmental conditions are very different in modern times and hence, most LED manufacturers assume that no degradation factors need to be included into their illuminance calculations.
The manufactures claim that the LED products are 100% efficient and that’s how they showcase their calculations to customers. This is not true in real sense, hence it is importantfor them to understand that maintenance factor is still an essential part of lighting scheme design.
Further, the manufacturers claim that with an LED, there is no degradation in lumen, driver performance, room reflectances and output due to dirt build-up on the luminaire.
As against these claims, experts say that LED lumen degradation is enumerated in the L70/80/90 figures showcased in luminaire data sheets. Even though driver efficiency is typically glossed over, there is a drop in circuit performance over time.
Due to heat sinks, LED luminaires attract dirt particles, which eventually create a dust duvet round the heat sink. This impacts heat dissipation from the LED chip, impacting LED lifespan and light output.
Need for proper standard method
There is no standard method for calculating these figures. LED manufacturers need to acknowledge that a maintenance factor of 1.0 cannot be justified. They cannot to get away by referring to long life of LED. At one point or the other L70/80/90 will be reached which will result in performance implication.