Putting it to the panel

The race is on to produce a glare-free LED luminaire product suitable for office lighting. Amanda Allen reports on a bench-test meeting between Mark Ridler, of multidisciplinary firm BDP, and GE’s Simon Fisher

The ascent of the all-conquering LED has, for the most part, been swift and far-reaching, providing viable lighting solutions for many applications. But office lighting has been an exception. Here fluorescents remain dominant as LEDs strive to offer the same quality at the right price.

Mark Ridler, lighting director at BDP, is comparing fluorescents and LEDs for office lighting and thinks the tipping point may be sooner than the industry expects. “It’s not quite there yet, but the time may well be soon,” says Ridler. With his comparison study in mind, Mark was eager to get his hands on the new recessed LED panel from GE’s Lumination range.

The product is based on a high-efficiency LED panel and includes pendant, recessed ceiling tile products and a vertical suspended version with a batwing distribution. The panel uses a US optical film technology that incorporates high-efficiency microprismatic materials. The material achieves an even distribution of light across the surface from two rows of Cree XP G LEDs mounted horizontally along the side of the panel. GE is licensing this material for use in its Lumination range.

Ridler got to grips with the recessed version, designed to fit into standard exposed T-bar ceiling systems. But the back of the luminaire also allows for bracketry for other ceiling types. The recessed product is the first to be introduced to the market designed for use in general commercial applications, including offices, retail and circulation areas, and this initial range comes in two sizes - 600 x 600mm and 1,200 x 300mm. It has an overall thickness of 14mm.

“What I really like about LED as a technology is its adaptability,” says Ridler. “Colour and intensity are easily changed to create different atmospheres and to service varying human tasks. This product is also small: 14mm is a very thin luminaire and freeing up 120mm of ceiling void can massively cut costs and overcome tricky co-ordination problems. “Until now I’d only specify LED panels for cellular office spaces where you have more control over the task area, which isn’t really appropriate for an open office space,” he says.

While Mark was familiar with the technology behind GE’s Lumination before he got to test the product for himself, what excites him about the product now is that Lumination marks a move away from the type of panels that are employed in backlighting televisions and more towards a product that is designed to project light.

But the glare rating of the product will have to meet glare standards for offices and when Ridler switches the product on, this question is foremost on his mind. His first impression is that the product is too bright and he puts this point to GE’s Simon Fisher, general manager of GE Indoor Luminaire Solutions.

Fisher replies: “The glare is effectively controlled by the prisms in the waveguide and UGR19 [the acceptable Unified Glare Rating for offices] is achieved for certain standard room configurations. We do get comment about visual brightness, which is made worse by the fact that we are usually switching on the fitting in a low ambient ‘presentation’ light level. But eye adaptation is rapid and surface luminance is lower typically than a T5 diffused product.”

Fisher adds that a new version will be coming out in the next few months that will lower glare and improve efficiency still further. Ridler says that’s important, given that visual comfort is a critical issue in office environments.

“A glowing, opalescent, uniform distribution in two directions isn’t going to be that useful to me, partly in terms of performance but also with regard to screen glare. Another issue is having a really bright object in peripheral vision - it’s likely to lead to headaches and distraction,” he says.

Once that issue has been addressed, however, he thinks the possibilities are enormous, because the panel doesn’t need to be square and there is no obvious reason why it can’t go around corners. In this respect, he thinks it might have similar potential to OLED.

Fisher responds: “Our innovation teams are working on making 3D forms and changes in shape in 2D is possible now. Our research centres in Shanghai, Munich and New York are working to develop the technology further. For now, we are focused on delivering 2D applications but we are willing to talk to designers about moving into the third dimension.”

Newer shapes also mean you could use the luminaire to achieve whatever photometric distribution you want, so it has a lot more to offer than an alternative to fluorescents.

Ridler says: “In the same way that the prismatic technology allows you to tailor your photometric distribution going down, you should be able to tailor your photometric distribution going up, which is certainly a very hard thing to do with fluorescents. You should be able to create photometric distributions previously unachievable.”

He believes these benefits may trump the issue of cost per lumen and may also allow designers to spread the fittings much more widely. “This will drive down energy use and please facilities managers, clients and architects, because it reduces costs and visual clutter,” he adds.

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