LIGHTING ECONOMIST
New sources, old fittings

You’ve got access to a game-changing new efficient source of light, so the first thing you do is bung it into one of your old fittings. Dave Tilley bemoans a lack of imagination

A strange phenomenon is happening in the LED manufacturing sector: the search for LED lamps and luminaires with the same characteristics as traditional lighting products. Also, a significant number of lighting manufacturers are simply installing LED modules in their current product ranges.

There is a consensus that LED technology makes it possible create lighting products that are cutting edge in terms of design and performance. Despite this, very few LED innovations push the boundaries of design.

Before I get the usual array of emails from lighting designers about bespoke LED products and designs, I want to make it clear that I am referring to traditional lighting products.

The search for lumen output equal to traditional light sources seems to be a never-ending competition between manufacturers. We started at 3W for an MR16 and have now achieved 10W and the signs are that the chip manufacturers will continue to improve this.

The question is: do we really need these wattages and the associated lumen output?

For example, the lumen output of a MR16 halogen is about 600 lm. The characteristics of a MR16 halogen will vary depending on the quality, but in practice there is a signifi cant reduction of light output during the first half of life. So the eventual lumen output would be about 300 lm.

Planned maintenance

Now consider an installation of 30 MR16s rated 50W. Unless the installation is subject to a planned maintenance regime – every six months, say – the lumen average will be about 50 per cent compared of the initial lumen output.

LED sources have the benefit of minimal lumen depreciation to L70.

Therefore the lumen output of the equivalent LED MR16 lamp is more likely to be 350 lm. This equivalence is important when replacing halogens with LED lamps because ‘look and feel’ is particularly important to retailers – as well as light levels.

Light levels are an important consideration because many areas have more luminaires than necessary. When an area is relamped with equivalent LED sources, there is a risk that the light levels will be higher than required. Perhaps LED manufacturers should focus a proportion of their research and development activities on dimming.

To take a specific example, the Toshiba 6.7W MR16 delivers 300 lm and output has diminished to 70 per cent after 25,000 hours’ use. Even taking a second tier brand, Opteon, the 6W MR16 delivers 290 lm.

Taking into account recommended light levels over five years, and the lumen depreciation and life of a 50W MR16 halogen LED lamp with lumen output of over 300 lm, the LED source will provide adequate illumination for most applications.

Perhaps LED manufacturers should focus their attention on product quality and performance – ‘Look and feel’ and light levels are particularly important to retailers Toshiba’s 6.7W MR16 delivers 300 lm particularly life and failure rates – rather than what seems to be a competition to find out who has the most powerful LED lamps.

Then there is product design. Once again there appears to be an attempt to recreate what what we already have but using LED sources. The best example of this is the LED tube. Why are manufacturers investing in LED tubes when LEDs can be used in entirely new designs that are innovative and improve efficiency?

A great example

A great example of innovation is the Dialight high bay. It may not look like a traditional high bay but its performance is exceptional and it is designed around LED sources and does not mimic existing products.

The attachment to traditional designs is compounded by manufacturers that are taking a shortcut to LED products. The introduction of LED modules to existing designs may well be an inexpensive route to entering the LED market, but the compromises on performance and quality will only damage the reputation of LED products over time.

The Lighting Economist’s verdict

The message to lighting manufacturers is: 

  • lumen output must be considered within the needs of the application;
  • designs should use the strengths of LEDs, not simply recreate what we already have; and
  • LED products must be designed as LED products, not an extension of an lighting existing range.

The convergence of energy and maintenance efficiency and how space is illuminated, in terms of lux levels and technology, should encourage lighting manufacturers to think more about the efficiency of design and technology and less about recreating existing design.

After all, if the design of luminaires does not embrace new technology we might as well continue to specify T5 and CMH sources.

You can contact Dave tilley at dtilley@nrgstar.com

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