LEDs seem to be ever expanding with a general rush to install them into as many applications as possible. However, LED technology was introduced with a specific purpose in mind and contrary to popular belief it is not suitable for every application. Adrian Kitching from Megaman explains some of the facts and the fiction.
A case in point is LED technology. The banning of the incandescent light bulb really started the ball rolling for LEDs and there is no doubt that it can do wonderful things, but it is simply not suitable for every application. For example, it would be totally pointless to replace a 28W 2D lamp with a 22W LED because 2D bulkheads are mainly used to illuminate stairwells and rely on the horizontal distribution of the beam whereas an LED alternative would give you the wrong type of beam distribution.
This approach of ‘making the technology fit the application’ has led to a lot of negative feedback for the LED with many people looking for alternative solutions. The key therefore is in asking the right questions in order to determine the right solution because by understanding the application you stand a much better chance of ensuring that the end user is happy.
End of life
As with any new technology, LEDs have moved on at a rapid pace and now offer a far more competitive solution with greater levels of sustainability, energy efficiency and performance. But perhaps the greatest change has been a decrease in the price which has made it far more appealing to the end user who is looking for a good return on investment.
One of the big issues surrounding LED lamps is life claims, with far too many manufacturers claiming a lamp life of 40-50,000 hours without explaining the rationale behind the statement.
It is not as easy as assuming that if a lamp has a longer life then it is a better lamp. Solid State Lighting (SSL) for LED has been around for many years and the recognised way to describe lamp life is L90 as this is the point at which the lumen output falls to 90% and thus the point at which a lamp change must be considered.
Some manufacturers will claim a lamp life of 50,000 hours in order to make the cost of ownership and payback models work to their advantage. What you need to bear in mind however, is that if this is based on L70 or 70% lumen output then you are not getting a better deal because it will still need to be changed when the Lumen output reaches 90% and therefore the claim of 50,000 hours is not a true representation of the lamp life.
The big debate
Another issue to look out for with LED technology is the lumens versus candela debate.
When specifying lamps in the past the manufacturer has always used Isolux cones and determined if the lamp is fit for purpose by understanding the candela output. Now however the company are seeing more and more importers using lumen output figures which have little meaning and are of no real use to the end user.
Lumen output refers to the amount of light generated within the lamp, but it does not necessarily follow that all of the lumens are actually used. The amount of light in a beam is determined by the candelas and it is this figure which should be used to allow you to make a true comparison.
