Introduction
Unforeseen Benefits
Other Considerations
Regulation
What is an LED?
Installation
The Bottom Line
Calculation
Conclusion
This article describes a scenario where Ohms and Watts Services (OWS) were called upon to replace traditional fluorescent lamps in a large school sports hall. This real-life example illustrates the benefits of re-fitting, with relevant facts and figures.
The fact that energy-saving bulbs cost less is simple enough to grasp in itself, but how much do they save? And, what about associated savings? This case shows how there may be additional factors to consider, beyond the issue of simple electricity consumption. The sports hall in question was originally lit by about two hundred traditional fluorescent tubes. The LED replacement bulbs not only consume less run-time power, but also may have a spectacularly superior lifetime. Standard fluorescent tubes have improved in longevity as technology develops, but often existing installations may comprise older types of fittings. In this case, the tubes to be replaced had a lifespan of about 5,000 hours. The new LED lamps installed, meanwhile, typically allow 50,000 hours of trouble-free use. In other words, a 10-fold increase. LED fittings are also less susceptible to damage from frequent turning on and off. A knock-on benefit in this case derives from the difficulty of replacement.
The sports hall has overhead nets installed - to allow the space to be used for indoor cricket practice, for example. Furthermore, the ceiling is very high. Therefore, changing fittings involves dismantling the nets to gain access, followed by use of a "cherry picker" crane to lift the maintenance personnel to the dizzy heights of the tube holders. The less this rigmarole is undertaken, the better, and hence there is an ancillary saving associated with use of the new LEDs.
And another thing: where does all that extra energy used by the old types of fluorescent bulbs go? Well, to a large extent it is dissipated as heat. It's fine to have heat when you want it, but not at the peak of summer, and probably not in the roof space.
Speaking of environmental benefits, there is also the disposal of the fittings, once exhausted, to think about. Standard tubes contain mercury, a notorious pollutant. This imposes a further management burden: the need for them to be properly dealt with at a designated recycling centre.
And another thing ... what about the quality of the light itself? Although the flicker of traditional tubes has been improved over the years, there may still be that almost-imperceptible wobble in the light quality. This may prove irritating in a sports hall, or a location such as a library where sustained visual focus is a necessity. LEDs also do not suffer from faint buzzing sounds and similar anomalies.
The behaviour of electrical circuits is not always as straightforward as it may seem to the untrained eye. Whilst it is common to talk in terms of wattage of components, the actual consumption can be affected by many factors. One of these is termed ‘power factor’. Some components, such as ‘ballasts’ in fluorescent tubes, may introduce inductance into the circuit. This may cause the voltage and current phases of the supply to become out-of-phase. The consequence of this is that the circuit does not operate efficiently, and there is greater energy loss than would otherwise be the case. This is another consideration which may mitigate against choosing traditional fluorescent tubes, in cases where the power factor is less than unity.
The UK government's Carbon Reduction Commitment (CRC) is a compulsory energy efficiency scheme, applicable, for the time being, to large businesses and government organisations. As well as paying for their energy in the normal way, the company or public body will need to pay extra "carbon footprint" allowance. Failure to register with the scheme, or inaccurate reporting, is punishable by fines. These may seem significant, but for larger organisations, more onerous will probably be the other incentive to comply: reputation. Under the scheme, the government publishes a league table disclosing the organisation's performance. Position in the table will determine whether a bonus is awarded or further penalty imposed.
Governments in other parts of the world are introducing similar regulations. If the trend continues, it seems likely that smaller organisations will become corralled into the regulations, as time goes on.
This puts an additional pressure on companies, public services and government bodies to adopt carbon-friendly technologies, such as LED tubes. Even if your organisation does not currently fall under the remit of the major legislation, similar rules may apply later. It may also be said that decisions will increasingly be driven by an implicit reputation-based pressure, deriving from the changing culture: organisations will want to deal with partners who are "seen to be green".
LED stands for 'Light-Emitting Diode'. So, they emit light; that's a good start. The real significance is in the term 'diode'. This is a semi-conductor component, which uses electroluminescence; in other words, similar to parts that make up circuit boards, an individual LED requires minimal energy supply. Over the years, developers of LED technology have achieved a broad range of light colours (originally only red was available). Now, even within the category of white light, a range of possible "colour temperatures" is available.
Additional beneficial features of LEDs include robustness (including being able to operate at low temperatures, and being relatively unaffacted by sources of interference such as magnetism), smaller size and faster switching speed.
Because LED tubes can be made to the same "form factor" (that is to say, with the same general shape and connections), the original housing can still be used. However, there are electrical changes to be made. The original tubes contain electrical regulator units known as "ballasts". These are no longer required. "Starter" components also need to be bypassed. Qualified electricians undertake all the necessary rewiring.
We provide not only the electricians, but economic pricing for all the new components; as industry contractors, we can source all the components for you. We can advise on which lamps are the most appropriate to fit. Power consumption will vary depending on the size of the fitting, but typical figures for one-inch diameter tubes are: 12 watts for a 2-foot tube, up to 33 watts for a 6-foot version.
As an illustration, here's a quick calculation, based on the above example.
Electricity prices are usually quoted in terms of "kilowatt hours" (kWh). A kilowatt is a unit which measures power usage per unit time. The price per kWh for domestic use (as of the end of 2001) is around 12 pence. Information about current prices in the United Kingdom can be obtained from OFGEM (www.ofgem.gov.uk), the government organisation which regulates prices. Prices for businesses varies widely, depending on credit worthiness, amount of consumption, location and trade sector.
Let's assume a price of 10 pence per kWh for this example. The sports hall had about 200 standard tubes, consuming 70W each. High walls without low windows in the facility mean that natural light is not abundant, so the lights are used even in summer. As a conservative estimate, let's assume that the hall is used on around 275 days a year (note that it is used for events even out of term time, and at weekends for various functions). Further, an estimate of an average 6 hours' use per day is allowed for.
Maintenance used to be done once a year (the lifetime of a standard bulb), and would involve the hire of a cherry picker and electrician for a number of days. The cost of this was £1500. Now, this cost can be spread across ten years.
One thing that skews the calculation against LED tubes is the fact that they are still more expensive than standard tubes. At the time of the installation (in 2011), a standard bulb retailed at about £6, whereas an LED replacement tube was £50. OWS offers competitive industry prices, but there remains, nevertheless, a significant difference in price.
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Step | Description | Calculation |
ORIGINAL CONSUMPTION | ||
1 | TOTAL POWER USAGE: | 200 x 70W = 14000W (or 14kW) |
2 | COST PER HOUR: | 14 x 0.1 (i.e. 10p per kWh) = £1.40 |
3 | COST PER DAY: | £1.4 X 6 = £8.40 |
4 | COST PER YEAR: | £8.4 X 275 = £2,310.00 |
5 | MAINTENANCE COSTS (per year): | £1500 |
LED CONSUMPTION | ||
6 | TOTAL POWER USAGE: | 200 x 28W = 5600W (or 5.6kW) |
7 | COST PER HOUR: | 5.6 x 0.1 (i.e. 10p per kWh) = £0.56 |
8 | COST PER DAY: | £0.56 X 6 = £3.36 |
9 | COST PER YEAR: | £3.36 X 275 = £924.00 |
10 | MAINTENANCE COSTS (per year): | £150 |
11 | LED BULBS ADDITIONAL COST (per year): | ((200 x £50) - (200 x £6)) / 10 = £880.00 |
TOTAL COSTS: | ||
12 | ORIGINAL TOTAL (per year): | £2,310 + £1,500 = £3,810.00 |
13 | LED TOTAL (per year): | £924 + £1,500 = £1,074.00 |
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TOTAL SAVING (per year): | £3,810 - £1,074 - £880 = £1,856.00 | |
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This example does show a steady monetary benefit can be gained from the use of LED tubes. Remember, this is just one room (albeit one with a high lighting coverage); imagine the benefits multiplied over a whole complex or institution. There may be an extra cost in rewiring, but this is a "one-off", and amortised by the first year. It seems likely that the price of LEDs will come down, whereas electricity prices may go up. These trends make the gains greater. However, not all the benefits are financial. There are several advantages (as mentioned above) in terms of light quality. Having to replace the lamps every year is also something of a burden to administrative costs and may disrupt potential users of the hall. Finally, not having to dispense with so many tubes, and their mercury contents, every year is surely beneficial to the environment.
If you would like more information about our energy-saving LED services, please contact us.