Shedding Light
on the Rapid Rise of LED
We hear thoughts from Graham White, lighting
technical manager at Eaton, as to why LED has stepped into the spotlight all of a sudden.
Lighting is one of the largest and most visible consumers of energy in business and, in some cases, can account for as much as 50% of all electrical consumption. In today’s efficiency-conscious climate, it is therefore vital that the correct lighting solution is deployed as part of an energy saving effort.
The rapid rise of light emitting diode (LED) lighting as a viable option for commercial and industrial applications has flooded the market with a wide array of products and information – this can create confusion among specifiers.
“The ‘practical life’ is defined as the period of
time between LED activation and the point at which its output falls below 70%.”
The appeal of LED lighting lies in its highly efficient ability to generate more light per unit of electricity than almost any other available technology. LEDs do not require mercury to generate light, they last up to 50 times longer than a conventional incandescent lamp and around five times longer than a compact fluorescent energy-saving light bulb.
In addition to their comparatively long lifespan and high degree of efficiency, other advantages of LED lights are that they are tough and vibration
20 | LIGHTING
proof, dimmable and small in size, as well as offering directional light, excellent colour saturation, unlimited on/off switching, no ultraviolet radiation and will typically reduce the direct infrared radiation.
However, despite the stated advantages of LED technology, its introduction into working environments comes with a number of additional considerations that influence its performance and cost-effectiveness.
The LED must be incorporated into a suitable luminaire. This process will inevitably result in a series of step- by-step reductions in LED lumen performance; therefore, the design of the luminaire itself is critical to ensure its performance.
While the performance of the luminaire is important, there must also be an understanding of the practical life of the LED and LED luminaire. Like all light sources, an LED source will gradually fade over a period of time. The device is considered to have failed at the point in time when the lumen value has depreciated to 70% of the initial lumen value.
Therefore, the ‘practical life’ is defined as the period of time between the LED first being activated and the point at which its output falls below 70% of its initial output. This is symbolised by the letter ‘L’ so, to give an example, a quoted specification might look like the following: ‘L70, 50,000 hours’ or ’50,000 to L70’.
It is vital to carefully consider the application to determine whether an LED is in fact the most appropriate solution for a particular situation. Applications where an LED does not
offer the optimum solution include situations where capital cost is the key driver, the project is intended to have short operating hours or the temperature of the environment is especially hot as can be the case in certain industrial areas. In contrast, there are situations where LED lighting is the obvious solution. These could include cold applications, environments where the cost of maintenance and replacement of lamps is difficult or expensive, or where the operating hours are such that the energy savings are warranted.
By looking at the lumen performance of the LED luminaire and not just its wattage, the specifier will be able to compare the true performance of the LED luminaire against a conventional lamped luminaire. This will identify the benefits in reduced energy consumption for a real application while retaining the correct illumination level and quality.
High-brightness LEDs are relatively expensive to make because of the precise production techniques involved in the manufacturing process. However, the comparatively higher initial outlay must be weighed against the total cost of ownership, which can be lower than conventional lighting because of the inherent energy savings and reduced requirement for maintenance and replacement bulbs. In many cases, the payback period can be remarkably short. This is dependent upon the purchase of properly engineered LED lights used in luminaires that are designed and built specifically for the purpose.
www.cooper-ls.com www.tomorrowsem.com
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