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Author: Llumarlite
Date: 11/09/2018

Don’t know the true cost of service?

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To accurately calculate the cost of your current lighting, you need to have a good grasp of several costs.  Namely:

  1. Operational hours of the luminaires
  2. Life expectancy of the luminaire and its components
  3. Life and light output of the lamps
  4. Man-hours to maintain the lighting
  5. Cost of luminaire components and labour
  6. Let’s look at the different costs you are currently paying.

1. Operational hours of the luminaires
Unless you have been properly maintaining your lighting and control systems, lights may already be stuck at full brightness or overridden on 24/7, hence costing a small fortune to operate and burning out lamps and control gear at an alarming rate.
Depending on your business, you may be running lighting 24h/7d; every hour of every day equates to 8,760 hours a year. 

You also need to consider the maintenance hours required to keep your lights on.  Let’s look at one example.
Lighting installed 2008, operational for 10 years: -

2. Life expectancy of the luminaire and its components
Typically, fluorescent luminaire components that were bought and installed in 2008, as above, would have a ballast rated life expectancy of 50,0001 hours. 
So, 24h/7d operation = 5.7 years

           1 Nominal lifetime up to 50,000 h (at typical ambient temperature 50°C with a failure rate ≤ 0.2 % per 1,000 h)

In Llumarlite’s experience, 10 years is a typical ‘useful service life’ of a fluorescent or discharge luminaire considering all parts of the luminaire fixture.

NB - Installed ambient temperature is often higher than 25oC, hence the temperature experienced by the equipment inside the luminaire could be > 50-60oC (exacerbated by lack of ventilation) - the light source and ballast will have a shorter life expectancy – e.g. 10 to 20% (5,000->10,000+ hrs) reduction of life dependant on Tc max. typically 70oC (Tc being the maximum ballast case temp).

3. Life & light output expectancy of the lamps
The average life of a lamp depends massively on numerous factors such as ambient temperature, number of switching cycles, dimming, constant low light level operation and the quality of the lamp chosen.

The ‘L’ value means the lumen depreciation of the lamp i.e. as the lamp ages and gets dirty the luminaire loses light output, aka service life.

The ‘B’ value means the rated lamp survival factor i.e. the percentage of failed lamps or below light output lamps.

The ‘H’ value is the hours of service life referred to.

So, L80 B50 means at the end of its service life i.e. 14,000 hours it may be achieving 80% of its initial rated lumens. 50% of the installed lamps will either have failed or be between 1-79% light output.

Average lamp life of T8 = 14,000 -> 16,000 hours L80 B50

Average lamp life of TC-L = 16,000 -> 20,000 hours L80 B50

4. Man-hours to maintain the lighting
Establishing the realistic costs to maintain your lighting may be harder than you think.  Quite often the logistics of establishing a suitable time, gathering lamps, ballasts, batteries and inverters from the storeroom, signing out keys to risers and taking a pair of steps or desk surfer across the site is quite a task.

Typically, this involves a two-man job from carrying spare components, job sheet, drawings, tools and access equipment from the basement, up lifts and carefully across office floors.

This work usually needs to be done outside normal working hours when the floor is clear of occupants making it easier to place access equipment amongst desks and with no injury risks to staff below.

If it is a simple lamp replacement, then this can be relatively quick, but time is consumed by the preparation work to get up to the luminaire and whether circuit isolation is required.

If the luminaire requires the replacement of a ballast, emergency inverter or battery pack it may be easier to remove the luminaire from the ceiling and replace the faulty components on the bench/floor before re-fitting the luminaire, re-instating power and testing its operation. If any emergency components were replaced, it will require re-testing and log-book updating to be compliant with regulations.

It really depends on the scale of the site, distance to travel to luminaires, moving of furniture setting up access equipment and the nature of the fault, hence the time involved.

Example: - For simple lamp replacements, on a medium to large site with 10 luminaires across 3 floors in different locations and 50% requiring a desk surfer. This will take about 4 hours. If it involves ballast/inverter/battery replacements it could increase to 8 hours.

5. Cost of luminaire components, labour and access equipment
From our experience, some large FM companies have individual strategists that work on whole site business cases but can be disconnected from their own maintenance departments running costs and purchasing arrangements, hence woefully underestimate the actual price, minimum order quantities, availability and procurement departments purchasing channels.

It is not uncommon for return on investment calculations to be based on £8 per ballast when the purchasing team buy them at over £25 to £30 with large minimum order quantities. (Remember- they only have to buy a couple at a time at first, so no special deals can be struck, then quantities dramatically escalate as we have explained to follow predictable failure curves

Typical T8, TC-L and T5 lamps are more commonly available and can cost between £2 to £3 per lamp. Minimum order quantities, delivery charges and safe lamp disposal charges may also apply, and lamps become obsolete. 

Access equipment may need to be hired for some jobs, due to a lack of site storage space. Don’t forget to include its hire charge and delivery costs.  If a desk surfer is required, you can budget £250 for a week.

Llumarlite has heard various charges for FM maintenance, but a typical cost can be £40+ per hour.

Based on the example above, spot replaced lamp failures could cost £470; therefore, an average cost would be £47 per luminaire. Ad-hoc ballast failures could cost £840; therefore, an average cost would be £84 per luminaire.
In summary, it is more cost effective to plan-ahead and understand your cost of frequent lamp changes if you have a 24/7 operation or to upgrade your lighting installation before it reaches end-of-life failure rates and you throw good money after bad.

Don’t just keep your fluorescents going, just to keep the lights on!
So, you have seen that the cost of replacing ballasts would cover much of the cost of a new, 50% more efficient LED luminaire.

Updating it rather than fixing it will immediately start making energy and maintenance savings and is a more efficient use of your money and time.


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Published on: 2018-09-11