LED lighting: Shining a light on grey areas

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Achieving efficiency is key, but there isn’t a single panacea. You have to consider the whole lighting scheme, the fittings as well as the luminaires, the maintenance requirements and the usage patterns of the building, explains Graham White, technical manager for Lighting at Eaton.

The appeal of LED lighting lies largely in its highly efficient ability to generate more light per unit of electricity than almost any other available technology.

In addition to their comparatively long lifespan and high degree of efficiency, other advantages of LED lights are that they are tough and vibration proof, dimmable and small in size, as well as offering directional light, good colour saturation, unlimited on/off switching, no ultraviolet radiation and will typically reduce direct infrared radiation.

In IT and data centre environments, important benefits of LED include the high-quality of task lighting, the neutral temperature of the luminaires themselves, energy efficiency during long operational hours and the elimination of disruption relating to regular servicing, maintenance and bulb replacements.

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Close scrutiny

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, and these should be considered by specifiers at the earliest stages of the decision-making process.

It is a process that also has the potential to be clouded by confusing claims from less reputable manufacturers, which is why specifiers must apply close scrutiny at all stages.

First, 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.

Maximising efficacies

To maximise the performance and efficacies of the total luminaire, a number of design elements must be taken into account. These include thermal management of the LED, the design of the optics and the quality of the driver.

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.

For LEDs, the metric quoted might be ‘L70B10 50,000 hours’, which means that 90% of the batch is still performing at a minimum of 70% of the lumen value after 50,000 hours.

It is also vital to carefully consider the application to determine whether an LED is in fact the most appropriate solution for a particular situation. In the lighting sector, LEDs are only one tool in a large toolbox containing many other viable lamp types.

While the LED is attracting high levels of interest, there are still many applications where conventional lamp types offer viable solutions. 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.

Once the decision to use an LED luminaire has been made, it is very important to engage with a reputable manufacturer, since manufacturing a luminaire with LEDs is not the same as manufacturing a luminaire with a ballast and lamp holders to accept a conventional lamp.

Buyer difficulties

The Lighting Industry Association acknowledges in its Guide to LED Lighting the difficulties that buyers may face when deciding between products: “Like all products, there are good ones and bad ones. As the technology develops, many more companies are offering LED products for sale and there are plenty of rogue claims being made for the performance of poor quality products. Always look to buy from a reputable manufacturer and look for evidence that the performance has been verified by an authority or third party. Buying poor quality LEDs is a false economy. We would recommend looking at the light output rather than the wattage to judge the lamp.” 

High-brightness LEDs are relatively expensive to produce 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.

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