In common factor, the installations illumination level is going down over time. Different factors of light source and environment will influence the lifespan of lighting such as ballast, led light chip, PCB board, heatsink, room condition and etc. Therefore, the lamp survival factor depends on the service lifetime of a lamp. If a lamp is not working any more, the decision for immediate replacement or group replacement needs to be taken.
Examples on lamp lifetime calculation:
- Working hours: 18 hours a day; and 54 working weeks a year, which is equivalent to 6,800 hours per year.
- Room is to be renewed after 15 years is equivalent to 102,000 hours in total
- Room are dirty
- Lighting system: 4 ft led tube closed luminaires (IP40)
- LED light sources
- The maintenance factor MF is 0.6; means that the new lighting system is required to be overdriven by 67% not to undercut the minimum required illumination level after 10 years.