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September 2013-Simplifying the Complexities of LEDs

LED technology is developing at a rate of knots never experienced in the lighting world before. So why the sudden rush for a technology that has been around for 100 years or so?



We can all thank the British designer Henry Round for the discovery of electroluminescence in 1907 alongside Russian scientist Oleg Losev for creating the first LED in 1927. However the market chaos which we are all experiencing on a daily basis can be widely attributed to the American Nick Holonyak Jr, who invented the first practical (and usefully visible) LED in the early 1960s. So again ask yourself why the rush now, when the innovation has been available for such a long time?
Is it escalating energy costs, product size, product access, changing standards, sustainability, greater performance, reduced entry barriers, or is it just plain exciting technology?
This question is a hard call, and it could be easily argued that the reasons are all of the above and some. So what this article serves to demonstrate is that LED is a wonderful new technology that has an abundance of benefits if designed and applied correctly, but if abused and/or applied incorrectly (and in the absence of qualified regulative standards) the luminaire choice will simply provide you with a LED that is a Light Emitting Disaster.
It is true that the original design application for LEDs was predominantly for electronic signals, and more refined use of the technology has been seen in the transport industry as signal lights and electronic standby signals, however it was the creation of mid and high powered LED's which excited the market to explore new (or should we say) explore traditional luminaire design opportunities.

Despite being a relatively new commercial lighting design application, LED performance principles follow very similar design and operating parameters as traditional lighting sources and not surprisingly, they exhibit the same performance outcomes. As a basic example: light = heat and heat = losses and losses = reduced output and design life.
So why are these factors so important?
Just like the humble incandescent globe, if you operate a lamp at 10% over the design voltage you will be rewarded with a higher output. Unfortunately you will be penalised with a significantly reduced design life. In comparison, LED's use complex electronic circuits to manage the system's electrical characteristic, however they follow the same principle ie: if you overrun the LED source you will of course increase the optical output, yet the service life will be dramatically reduced. And sadly, once the system is subjected to the system overload, its life can never be returned to the original design parameters.
The same rules apply with colour temperature of a lamp source ie: change the operating parameters and you will experience a change in colour temperature, which is fine if you only have one luminaire installed in a given room. But when you have multiple products and you do not want the design to look like a Christmas tree, colour temperature becomes a very ugly issue to resolve.
Whether your lighting design calls for traditional light sources and/or more commonly - LED technology, the same rules apply. So when you are promised design performances or excessive life time guarantees without qualified certification - buyer beware!
A further example of misinformation that is seen on a regular basis is the comparison of LED wattage to traditional sources. For example, how often have you seen a claim advertised like the following: "Buy our new LED 100w floodlight with the same output as a 250w HPS floodlight and save!". As with heat, in the lighting world "lumens" is "lumens", there is no substitution. So if you see a product with excessive savings in power consumption without creating the equivalent lumen output, the only thing you are saving is the education process your client will receive once they realise that the product does not perform to their expectations.

The risk of claiming design performance and/or expected service life becomes a very scary obligation when you are not sure what test procedures (if any) were conducted.
What is very important to be aware of with this technology (which simply reflects the speed of the market activity) is that apart from mandatory Australian safety standards, LED's (unlike their traditional sister lamp sources) are currently not covered by any Australian minimum performance standards. Hence the risk of claiming design performance and/or expected service life becomes a very scary obligation when you are not sure what test procedures (if any) were conducted. This is even more relevant when it's an unbranded product and/or if a guarantee of 50,000 hours is offered and you are not even sure if the company you purchased the product from will be around to honour the guarantee.

For a moment just ask yourself: "how could I accept a 50,000 hour design life warranty (which based upon an annual average consumer usage converts to a 16 year guarantee) from a company that was created last year?" Surely that is a commercial risk that no reasonable consumer would accept, whether it be applicable to lighting or any other consumer product.

To address the availability (or lack thereof) of minimum performance based standards and to take leadership with this lack of regulation, the Lighting Council of Australia has introduced a voluntary program which invites participating members to submit authorised test documentation to the Lighting Council for verification and certification - this being the SSL program. In the absence of the SSL certification and in the interim of minimum performance based LED standards, you as a consumer should be asking for verification of key safety compliance certifications such as EMC, SDOCS (suppler documentation of conformity) photometry and claimed design life. Otherwise you as the installer are accepting the commercial risk of the product performance claim.
Along with the principle of the SSL program, reputable LED lighting manufacturers publish product performance specifications namely LM-79, which outlines performance documentation for LED luminaires and LM-80, which outlines the performance limits of the original LED. What is very important in reviewing these documents is to be sure that they are read in conjunction with each other, as the individual performance limits of each report is critical for the product's optimum performance, and in particular the thermal limits of the LED source and the luminaire. It is quite common to see reports generated from both Europe and Asia quoting an exterior product with design thermal limits of 25 degrees ambient, which is great for Australians who only wish to use the product in the gorgeous natural environment of Tasmania, or only during winter months outside Western Australia, Northern Territory or Queensland. Remember: light = heat, heat = losses.
To address the unique and arduous Australian environmental demands, Australian lighting manufacturers (albeit those with common sense) will demand exterior product construction meet a thermal ambient design limit of 40 degrees. As previously outlined, if this demand is adhered to, the design life expectations will then be met and fundamental mechanical requirements such as the gaskets, seals, paint finish etc will be fit for purpose. Despite UV not being a lamp design constraint with LED technology, the harsh Australian environment does not change its position with the degradation of product materials just because the product uses a LED lamp source.
So taking what we have learned with regard to the similarities of traditional lighting product design and performance limits in comparison with LEDs, ask yourself the following question:

How does a designer choose the right lighting source?
If you start with the basic principles of light = heat, the market has demonstrated that with authorised and independently certified products, LED is a sustainable choice with small to medium luminaire performances typically in the range of 500 lumens to 3000 lumens for most interior downlight applications, decorative strip lighting systems and small to medium bulkhead and decorative designs.
As LED designs have increased in output and importantly address an increase in IP ratings for exterior products, viable product designs have been created and as efficiencies continue to accelerate, so will the advancements in this market sector. The key challenge for this market sector (as highlighted previously) is the balance of output and heat management for arduous Australian industrial environments where thermal ambient temperatures of 40 degrees are commonplace.
Now linear LED troffer modules are here and again, with suitable accreditation they become an interesting choice. However strict Australian Interior Standards performance requirements for this market sector are being set, particularly for Green Star designs. LED options are a little more difficult to achieve, especially when glare ratings become a criteria.
Given the speed at which LED technology is moving, by the time this article goes to print there will almost surely be a new development that will challenge all that has been said. But despite the dizzy speed of development, don't forget the basics that should serve as your "lighting checklist": light = heat, heat = losses, lumens = lumens.
Market leaders in any given sector exist for the same reason: - service, sustainability, innovation and reliability. With 20% of the world's electrical consumption attributed to lighting and acknowledging the need to embrace cleaner energy technologies, the investment in creating energy efficient and sustainable lighting solutions is now of paramount importance.
Michael Farmer National Marketing Manager
Pierlite Australia Pty Ltd