1. Understanding Lighting Maintenance
Lighting Maintenance is completely misunderstood and overlooked, by Management, as a single focus in almost all
commercial and industrial facilities. Lighting usually is included as part of the overall maintenance cost or if
segregated included with other electrical equipment which includes air conditioning, refrigeration, motors, lifts
etc. This other electrical equipment does age over time but requires only periodic maintenance in line with all
building mechanical services.
It would seem natural enough to combine lighting in the mix until one realizes that lighting lamps all have a finite
life and their lumen performance reduces dramatically over life.
The common belief is that this is not a big consideration as current lamps are relatively cheap and at one or a few
replacements at a time does not normally ring financial bells and therefore no analysis is made to consider the cost
over time.
It is generally understood that lighting efficiency of performance is a necessity for productivity and an absolute
essential for retail display but there is a lack of understanding of lamp performance over life.
The following are the most common lamps used in retail and commercial service today:
 36 watt T8 fluorescent lamp.
 compact fluorescent lamps (CFLs)
 50watt tungsten halogen MR16 lamp
 35w, 70w and 150w metal halide lamps
The following diagram shows the life performance of these lamps and is taken from a compilation of major brand
manufacturer’s literature.
From the diagram it is important to take into consideration that:
1. The end of life (see dotted line) is based on 50% of the lamps in an installation having failed.
2. There is a major reduction in performance over the life of each lamp.
3. This diagram represents quality brand lamps operating in perfect conditions.

2. In commercial practice no one would accept trading with 50% of the lamps out but people get confused by “rated
life”.
No one would buy a car with 6 cylinders and allow it to run on 4 cylinders still consuming the same fuel. No one
would employ their team on their current income and have them work half their time.
Without understanding lighting maintenance, people do operate their lighting systems with a reduction in output
which fails to produce the lighting effect required whilst still paying the same electricity bill. Lamp change timing
should be reflective of the end of the capability of the lamp to be productive for the task.
All lamps exhibit some reduction in light output over time. Manufacturers report light output at 40% of rated life as
an indicator of maintained light output. This value is close to the average light output over the life of the lamp and
is called mean light output, mean lumens, or design lumens.*
Light fitting performance is designed around specific lamps. If replacement is with a different lamp shape and
measurement the performance will be very different and most times drastically reduced. The operating
temperature of the environment and switching cycles plus the quality of the lamp brand purchased all affect lamp
life, quite dramatically.
Another important issue to consider is that the average rated life of a lamp is dependent on the type of ballast
used to operate the lamp. If ballasts other than those recommended by the lamp manufacturers are used, specifiers
should inquire about the impact that those choices may have on mean light output.**
The high cost of labour and the cost of specific equipment used to change lamps (most often after trading times) is
also overlooked or hidden in the general costs of operation in a commercial facility.
Electricity costs continue to rise dramatically. Lighting technology growth is accelerating rapidly with a vast range
of new and confusing lighting products, most providing a reduction in energy used. Unless lighting maintenance is
isolated it is difficult for management to recognise the need for or understand the correct equipment to benefit
from these savings.
For example most suppliers of LED lighting quote very long life for their products but warrant supply of the
equipment only for between 2 and 3 years. What they forget to advise is that you cannot replace a LED source at
the end of life but must replace the total light, leaving responsibility for a complete replacement including labour
with the purchaser.
It is extremely important to have a highly experienced lighting maintenance service with the knowledge to provide
a correct cost saving and quality lighting performance, maintenance program.
Going forward this service provider should also be able to provide in-depth advice of the benefits and pitfalls of
new lighting technologies.
Lionel Barden
Managing Director
* ** ©Rensselaer Polytechnic Institute. All rights reserved.