Light costs money and the more light you want, the more money it is going to cost. This simple statement has driven lighting specification since Edison was a lad and it doesn’t matter that we’re entering a whole new phase of energy efficiency; light still costs money. So when a company needs at least 1000 lux of good quality light for it to do its work effectively, the issue of system cost looms large in the decision-making process.
The project concerns the re-lighting of a body repair shop for luxury motor vehicles. Visual accuracy is paramount, both in the ability to see clearly but also to judge the accuracy of colour finishes. Lighting product reliability and minimal maintenance requirements underpin the selection of the specification. The existing installation uses metal halide lamps that have given good, reliable, service for many years. As a consequence, the client sees no need for a change in technology and expects a one-for-one lighting upgrade.
The conventional response
Until recently, metal halide technology was the only source that could meet the combined brief of ensuring good colour rendition while delivering enhanced illuminance levels. Energy efficiency of the metal halide lamp has always been more than acceptable, with performance figures in excess of 60lm/W and colour rendering in excess of Ra80 for lamps with cool white colour temperatures (>5000K).
Finally, metal halide lamps have a long life of 20,000 hours, requiring lamp changes after 5.5 years, based on an expected annual usage of 3600 hours.
With figures like these, it would have been an obvious solution to return to this type of installation. However, LED technology has delivered a light source that not only challenges this kind of performance, but effectively makes metal halide technology obsolete.
The value proposition
LED lighting has recently entered the industrial lighting arena and is already demonstrating that this new source can deliver a high level of performance. In all aspects, the LED source out-performs conventional metal halide solutions.
Applying these performance figures to the paint shop project, two factors are immediately apparent; not only does the LED out-perform the metal halide lamp but, in practice, fewer luminaires are needed to deliver the desired performance. The numbers speak for themselves:
Return on Investment
The figures show that the initial higher cost of purchasing the LED installation is quickly recouped by the significantly lower energy cost. Even allowing for the slightly higher annualised maintenance cost of the LED luminaire, due mainly to exchanging the entire LED fixture at the point where the output of the LED falls below acceptable levels, the return on investment occurs within the first sixteen months of operation.
Difference in capital spend:
£11475.00 (LED) - £6985.00 (MH) = £4490.00
Difference in annualized energy + maintenance cost:
£8000.20 (MH) - £4520.77 (LED) = £3479.43
After one year and four months, almost three-quarters of the additional capital spend on the LED installation is returned year on year for the life of the installation.
- To help you make further strong financial lighting decisions visit this year's LuxLive. The exhibition will take place in London on Wednesday 23 November and Thursday 24 November 2016. You can find out more by clicking here.