The Dazzling Dilemma of LED Lighting
LED lighting is a hot topic; energy prices are rising and the commercial world is pushing to reduce carbon emissions by considering a broader scope of low-carbon options.
7th August 2012 | Craig Smith: Associate Director, Rolton Group
Whilst in comparison to many other building services elements its point load is relatively low, lighting can account for as much as 30-40% of annual energy consumption when occupancy models and the building system as a whole are considered. This makes it an integral issue, and one which requires attention.
So, are LEDs suitable for the commercial world? Yes, they are. Are they commercially viable in the current economic climate? Now this is a real topic for debate.
During manufacture, LEDs go through a process called “binning,” during which they are split into various categories. Their placement is determined by a quality control procedure which measures light output, colour quality, and consistency of both of these within the lamp cluster. The lower priced luminaires with LED lamp sources therefore tend to come from the lower end of the quality binning process and the higher priced luminaires from the higher end of the same scale.
Engineers like to design systems in the knowledge that the calculations they undertake will be replicated on site. Therefore, as a lighting designer I would only use LEDs from the higher end of the “binning” scale, which comes at a cost. A luminaire to replace a typical 26W compact fluorescent down light costing approximately £70-80, would come in at a significantly higher price of up to £180-220.
However, LEDs last 50,000 hours, whilst their fluorescent equivalent will manage 20,000 hours at most, if electronic control equipment and triphosphor lamps are used. In terms of energy use, the light output ratio of LEDs is close to 1.0; this means it approaches 100% light output with no internal losses or inter reflection, which reduces consumption and in turn requires fewer luminaires. There are also fewer wiring points, cutting holes and labour when dealing with LEDs. Still, the cynics (including myself) will struggle against the fact that two or even three compact fluorescent luminaires can be bought for the same price as the LED equivalent.
So why consider LEDs? As I proved by designing a new teaching block for a school based on LED luminaires throughout, the lighting load can be reduced to around 7W/m sq. compared to the well-publicised industry benchmark of 10-12W/m sq. This equates to in excess of a 30% reduction, an indisputably impressive figure. In this case, the design of the LED lighting was in fact enough to omit the need for photovoltaic (PV) panels on the roof, associated support systems and interconnections, and gain a Building Regulations UK Part L pass with flying colours through an SBEM simulation.
In summary, LEDs do work, but can we afford them? Can we justify their use in a commercial world during economically tough times? If designed correctly- maybe, but as with any technology life cycle, costing becomes key. It’s a shame that in the current climate capital cost outlay is becoming more of a driver than whole life cycle costing, but times are hard and this is an inevitable factor. We face a catch-22 situation: until the technology is used regularly the costs will not decrease, but the costs will not decrease to make the systems viable until they become more widely used.
The future of LEDs is somewhat unkown. For use in emergency lighting, it’s a no brainer: discreet, powerful and economical, LEDs are becoming commonplace. Their general use in circulation spaces such as WCs is also viable, but there is still some way to go in terms of economic justification before their use in areas of higher illuminance, offices, classrooms and the like, becomes a generally feasible option. The use of display lighting in retail and similar applications should, in my opinion, be based entirely on LEDs, which offer superb colour rendering and controllability. As well as significantly reducing energy consumption from lighting, it would also make the shopping experience slightly more comfortable; people would no longer have to stand under the heat of halogen and equivalent lamp sources!
I suggest that those who can influence this change do so, as LEDs are the way forward. Think back to compact fluorescents; no-one wanted to change their good old 100W GLS bulb for an 11W compact fluorescent, but phasing out of the GLS lamp sources and an increase in awareness and confidence soon changed that. Controversial thought for the day: perhaps the commercial world should start to phase out compact fluorescent lamps...
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