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What is Lighting Maintenance Factor?

Lighting maintenance factor is a number that describes the reduction of lumens, or light levels, over time. 

With this, you can determine how well lit an area will be over time. With the advent of LED, lighting maintenance factors have increased significantly over fluorescent and HID counterparts they were designed to replace.

Lighting should be designed for the required lighting levels at the end of life. The lumens of a light or fixture decreases over time. This is normal. No lighting product will last forever. Lighting standards, such as lighting maintenance factor, help you choose the right lighting fixture for different areas to maintain the proper light levels.

 

Lighting Maintenance Factor and Scheduled Maintenance

A facility managers know how often to clean the room, the luminaries and lamp changing needs. We would find a reasonable time between maintenance and operating hours, as maintenance cycles are connected to costs. More luminaries equals a longer the operation time without maintenance. A higher frequency of maintenance cycles equals a higher maintenance factor.

 

Which factors influence the Maintenance Factor?

The installations illumination level is going down over time. Different factors influence the decrease in lighting level. Factors include soiling of surfaces, luminaries, lamp failure and depreciation of luminous flux by the light sources.

Example – Light depreciation – Loss of luminous flux over time

Room Surface Maintenance Factor

The room surface maintenance factor is the ratio of the room surfaces reflectance before and after cleaning. It is the reduction of the lighting level according to soiling of the room. It depends on the conditions in a room, if the room is very clean, clean, dirty or very dirty. The more dirty the room, the lower the maintenance factor.

 

Luminaire Maintenance Factor

The luminaire maintenance factor is the ration of the luminaries luminous flux before and after cleaning. It depends on the luminaire construction and design (open housing or closed one) as well as on environmental conditions (dirty or clean). The higher the luminaries protection degree from dust, and the cleaner the room, the higher the maintenance factor.
Consider the accessibility of the luminaries when setting up the maintenance plan. The more difficult to reach, the more the maintenance costs will be.

 

Lamp Maintenance Factors

1. Lamp Lumen Maintenance Factor

The lamp lumen maintenance factor is the ration of luminous flux at a specific time compared to a new lamp. It is describing the aging of the lamp or the reduction of light intensity over time. Manufacturers offer comprehensive tables about their lamps luminous flux behavior.

 

2. Lamp Survival Factor

The lamp survival factor depends on the service lifetime of a lamp. Some lamp lifetimes are reduced by frequent switching. The lamp manufacturers provide tables indicating the lamp survival factor. If a lamp is not working any more, the decision for immediate replacement or group replacement needs to be taken. If the lamp is replaced immediately the LSF can be set 1. LSF 1 is saying that there will be no loss of light because of lamp failure. The decision could be to replace lamps in special terms or group-wise. This could be the case in huge halls, where machines need to be stopped to reach the luminaries.

 

Lighting Maintenance Calculation Examples

1. Open-Plan Office (50 employees)

  • Working hours: 5 days a week, 16 hours per day, 50 working weeks a year (4000 hours per year)
  • Office renewed after 10 years (40,000 hours total)
  • Rooms are very clean
  • The room and its surfaces are cleaned regularly
  • Lighting System: 4 ft led lights closed luminaries (IP40)
  • LED light sources

Maintenance Factor MF:

MF =Room Surface
Maintenance Factor (xm)
Luminaire
Maintenance Factor (xe)
Lamp Survival
Factor (x)
Lamp Lumen Maintenance Factor
very clean roomclosed luminaireGood – no chance of damageLED luminous flux degradation over 50,000 hours
MF =0.970.9210.9

Total Calculated Maintenance Factor = 0.8

Open Plan Office – Maintenance Factor with LED

 

 

2. Factory Location (2000 sq ft) with LED Lighting

  • Working hours: 7 days a week, 18 hours per day, 54 working weeks a year (6,800 hours per year)
  • Factory floor is going to be renewed after 15 years (102,000 hours total)
  • Rooms are dirty
  • The room and its surfaces are cleaned every 5 years
  • Lighting System: pendant closed luminaries (IP64)
  • LED light sources
MF =Room Surface
Maintenance Factor (xm)
Luminaire
Maintenance Factor (xe)
Lamp Survival
Factor (x)
Lamp Lumen Maintenance Factor
dirty roomclosed luminaire (IP65)Good – no chance of damageLED luminous flux degradation over 100,000 hours
MF =0.90.9410.7

Total Calculated Maintenance Factor = 0.6

3. Same Factory Location (2000 sq ft) with HID Lighting

  • HID light sources
  • Replacement every 2 years (13,600 hrs)
MF =Room Surface
Maintenance Factor (xm)
Luminaire
Maintenance Factor (xe)
Lamp Survival
Factor (x)
Lamp Lumen Maintenance Factor
dirty roomclosed luminaire (IP65)HID service lifetimeHID luminous flux depreciation over 13,600h
MF =0.90.940.840.65

Total Calculated Maintenance Factor = 0.46

 

Conclusion

Be careful when setting up a lighting installations maintenance plan. This starts already with the choice for the light source. LED Modules are very efficient, are likely not failing and offer long lifetimes between 50,000 hours and 100,000 hours. The control possibilities are comprehensive. The luminaries overload that need to be installed to guarantee the end of lifetime illuminance levels light management systems. LED is the the most competitive light source. The features are dominant over traditional light sources.

Install or renew the lighting system by using energy efficient LED light sources and luminaries. Your world will be a greener place in the future.

Converting over to LED? We offer free photometric light designs to take the risk out of converting to LED.

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