What is the difference between edge-lit and backlit panels?

This question has been answered by the technical team at Integral.

The LED panel is the fixture that is making the largest contribution to energy savings in the corporate sector. The switch from fluorescent louvred ceiling grid units to LED is well underway, and growing rapidly thanks to tax breaks and other government incentives. Organisations across the UK are refurbishing their offices and enjoying immediate savings direct to the bottom line – but which format of panel do they choose?

Since their introduction, LED panels have been available in two distinct designs: side/edge-lit and backlit. Let’s explore the advantages of each design and consider which is best suited for your next project.

Efficacy

Short-lived tubes and ballasts and, of course, the dreaded flickering were reasons why fluorescents were disliked by office workers and managers alike. Initial versions of the LED replacements offered only a marginal benefit in terms of luminous efficacy – 64 lm/W were swapped with 78 lm/W when the first edge-lit LED units appeared. Over time, each new generation of LED panels has delivered improved ratios of power to light. To the extent that Integral’s new 152 lm/W backlit panel prompts the question whether it is now worthwhile to replace first-generation LED panels with new?

Edge-lit versus backlit

In edge-lit models the LED chips are arranged on the inner edge of the luminaire. The light is then bounced downwards through a diffuser. Edge-lit was the most popular format in the LED panel category during the introductory stage of the LED lighting market. However, there has been a parting of the ways between models in terms of efficiency.

Backlighting has proved the natural benefit of projecting light through less material. Edge-lit retains a share of the market where unit costs are a higher priority than running costs, and where there is an aesthetic preference. However, the real saving is in the lower operational costs delivered by backlit panels.

The bottom line

Corporate cost savings are a hard-nosed decision. With every breakthrough in luminous efficacy in terms of power to light, the payback time on installations shortens, while the unit cost of LED panels continues to fall. Additionally, recent government-backed initiatives, including interest and tax-free loans promoted through the Enhanced Capital Allowance scheme, is pushing refits higher up boardroom agendas.

Choosing to switch from fluorescent lighting schemes to LED panels for an office has become a no-brainer for both commercial business and public organisations. Increasingly, the need to replace less efficient legacy LED panels with newer, more efficient models will be on the schedule too.

 

If you’d like to ask a question about lighting, write to our Application Editor,
John Bullock: askjohn@luxreview.com

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Comments 5

Can you comment on the use of PMMA (optical acrylic) versus PS (Polystyrene) in these “Edge-lit” type panels? Many cheaper panels are PS which I believe is environmentally a bad choice?

Hi Sebastian, Some times edge lit panels seems to have a high glare

Hi Sebastian, Some times edge lit panels seems to have a high glare

Hi Sebastian, Much depends on the type of "diffuser" that is used. Edge-lit panels which use a good quality light guide can be fairly low glare. However, a back-lit panel can control the light more and be even less glaring. You need check the data sheet carefully. The other aspect is luminance. Obviously, the greater the lumen output, the greater is the luminance. Beware of high output panels. You can read my review of popular panels in the latest issue of Lux.

Interesting ! One question left : what about the luminance and glare of both solutions today? Thanks in advance for the answer ;-)

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