When Edison approached his customers with the first lightbulb, did they go to their existing candle and gas fitting suppliers to ask them how to judge that bulb ?
LED lighting is the current buzzword for an easy route to reducing energy. Simply change your light bulb and you will save energy. The mantra is commonly accepted and household, builders and commercial enterprises are all rushing to make that change.
And yet this is completely unregulated technology. How do the consumers know what to buy ? The product claims “equivalent to 50W halogen downlight, lasts for 50,000 hours, guaranteed for 5 years”. Let us examine these claims:
1) Equivalent to 50W halogen. In what respects ? It may mean that the fitting suits your existing 50W fitting. Does it mean that the light output is the same ? Light output is defined in lumens and a 50W halogen light generates over 800 Lumens. There is not one single LED lamp which generates 800 Lumens. Does it mean that it is a familiar warm light which dims to a satisfying orange glow ? A 50W halogen has a colour temperature of around 2600Kelvin which warms up to around 2200K at a low dim level. No LED lamp on the market today can emulate this. There are LED lights which can achieve a genuine equivalence to a 50W halogen but they are specialist products.
2) Lasts for 50,000 hours. An LED can last for 50,000 hours - ie around 8 years with the lights on all of the time, but how much light is generated at 50,000 hours and what colour is it ? Unless you know exactly the testing conditions and the anticipated Lumen output reduction rate, unless you understand the heat dissipation mechanism and the anticipated catastrophic failure rate your LED lights will be a range of different colours and really rather dull in 50,000 hours.
3) Guaranteed for 5 years.(Some manufacturers claim 10 years). Guaranteed to do what in ten years ? Yes they will probably be on, but how do you assess what is too dark or what colour shift is covered ? What will the manufacturer do when you call up and claim new fittings ? Even if they do replace them, how do you guarantee they are the same colour temperature, the same LED bin, the same light output and even the same bezel colour as the original. After all, replacing one will look rather odd against all the others unless you really have that answer.
The truth is that as in any ground changing technology there is a desperate fight as the established lighting suppliers, who have made their billions exploiting a technology created over a century ago, jostle with the young hi tech engineering turks who really understand the technology, who push the envelope and who are genuinely offering a brighter, better world of light. We, the modest consumers are merely pawns in this battle.
This leaves the professionals in a bit of a jam. A builder or electrician is obliged to provide Part L2 compliant LED lighting. Supply inadequate LED lights and you get an unhappy customer, or the compliance officer will reject them and new lights will have to be sourced. Architects are constantly swamped with handsome brochures showing handsome LED light fittings. They cost a fortune, yet how does that architect judge how much light, what colour they will be and what dimming system will work, as well as the issues of longevity and colour maintenance.
The light output from every single LED manufacturer is different. How do you know if that light will provide the light you need ?
So, if good LED lights do exist, where do you get them ? The answer is to employ a specialist lighting designer who will layout the lighting and define the exact LED light for that job. The responsibility is then on them to support the claims with proven tested criteria and to manage the guarantee. They can model the light levels and show you exactly what light you will get before you make any purchase. Yes there will be a slight cost - a lighting designer will cost around £400 a day, but that is small beer relative to choosing the wrong LED lights.
Ian Peter MacDonald - MacDonald Tait Light - ianpeter@macdonaldtait.com - 24th October 2011
