If your work space is still lit using 4 x 18w T8 fluorescent or 3 x 16w T5 fluorescent units, you should change them NOW. There is a huge range of more efficient LED ceiling panels available. We have looked at panels from the budget end of the market to through to quality engineered units with sophisticated optics.
Panels come in two versions
Most of the panels are edge-lit, also known as side-lit. This is where the LEDs are located around the sides. There are other deeper, troffer type panels known as back-lit. These have the LEDs mounted centrally above the diffuser.
Edge-lit panels can be very slim and are often used as retrofit lighting for lay-in tile ceilings. They also tend to be cheaper than troffer types. Side-lit panels have separate, remote drivers whereas with back-lit panels the drivers are built in.
The main advantage of back-lit panels is that they deliver more light output per watt than edge-lit. For the same illumination level in your workspace, the back-lit panel might consume as much as 25% less electricity than its equivalent side-lit version. There are big differences between the manufacturers. Even from the same manufacturer, there can be a 15 – 20% difference.
Of course, back-lit panels are much deeper than side-lit. Typically, they might be 75 - 100 mm high compared with 12.5 mm, or less, for side-lit.
Some manufacturers offer both back-lit and side-lit. They might also offer several versions of edge-lit which differ in quality and price.
Appearance and Glare
When you consider the appearance of the space, remember that a flush, recessed luminaire cannot emit any light on to the ceiling. I.e. the ceiling won’t receive any direct light. Unless the floor and desk tops are quite pale coloured, the room can look gloomy and you may not even meet the minimum requirements of workspace regulations such as BS EN 12464-1. Many lighting designers and consultants dislike panels for this reason.
Related to this can be glare from the panels seen against a dark ceiling. Some LED panels emit 50% more light than the fluorescent units they are replacing. This makes them more glaring. More light output doesn’t necessarily mean better lighting. You could dim the LEDs but a better solution is to use a lower wattage panel but with similar light output to the fluorescent one.
An alternative is to increase the light on the ceiling by using additional uplighters.
We often assume that the workspace will have positive polarity computer screens. E.g. black lettering is seen on a white background; examples are text documents or spreadsheets. In this case, the maximum panel luminance limit (in BS EN 12464-1) is 3,000 cd/m2.
However, a lot of CAD and drawing software displays lines and text against a black screen and the maximum recommended panel luminance for these fixtures is 1,500 cd/m2.
To reduce the risk of glare, look in the data sheet for the maximum luminance (cd/m2 or Nits) of the panel and also the intensity at different viewing angles.
Finally, it is common practice to install panels in place of one or more ceiling tiles. I.e. they are spaced apart in multiples of 600 mm centres. But how do you know that the new panel you choose won’t produce uneven lighting across the workspace? Often, this information isn’t provided in the data sheets, especially on budget range fixtures.
Some LED panels emit light at a higher angle than a louvred fluorescent. This is likely to mean they are more glaring. Conversely, some LED panels can direct too much light downwards and you may not get enough light on the walls or people’s faces.
The solution is to compare the glare rating and uniformity on the old and new panels. I could write a whole article about glare and the UGR system but I will just highlight one aspect of it. The software assumes that the appearance of the panel at various viewing angles is homogenous. I.e. uniform across the whole of the luminous area you can see. However, some panels emit light over only a small proportion of the 600 x 600 mm face. This inevitably means it is more glaring but there is no simple way of calculating by how much.
But how much do they cost? Unless you have a specific project with a specific quantity, it is difficult to get a firm price, especially bearing in mind that some fixtures can be ordered direct from the supplier whereas others are sold via various distribution channels such as wholesalers.
Cheaper panels are often used for temporary or small office installations where durability and energy saving may not be important. More expensive, specifier panels are usually ordered for large projects.
The star ratings are only approximate because of the difference in price, build quality, energy and optical performance. The ratings are based more on value for money than absolute build quality and optical/energy performance.
Why pay more?
There are lots of reasons for spending more than the bare minimum for a panel.
Maybe the most important reason is how long to you want the panel to last.
The Lighting Industry Association laboratory tells us that a common feature of low-cost panels is that the light output drops rapidly over a period of time. The worst ones lose 30% of their output within 1,000 hours – that’s about four months use in an office. You may not notice the reduction visually but remember: a) you are not getting what you paid for and b) the illumination level may fall below national standards much sooner than you planned.
Another common failing with budget panels is that the edges of the diffuser go yellow after a short space of time.
Many established companies have been manufacturing LED panels for 10 – 15 years. They know how to make them last.
Another reason to pay more is a lower running cost. Efficiency is a word which is often misused but efficient drivers, optics and LEDs can sometimes reduce running costs by 25% compared with “cheaper” panels.
Providing reliable data costs money and time. Independent testing has to be paid for. If you don’t trust the luminaire data sheet, don’t buy the product.
Quality manufacturers have a reputation to maintain. Unreliable equipment is the quickest way to lose that reputation. Be careful of companies that quote the rated life of the fixture longer than they, themselves, have been in business.
Finally, there is the reassurance, backup and service you receive from the established companies. This cannot be costed but can be worth far more than the cost of the equipment.
First choose the panel that meets your lighting needs and those of your staff, and then look at the price. Always check the rated life and the guarantee.
Don’t be tempted to use a panel with high lumen output even if it is efficient. Loss of productivity due to glare will cost a lot more than any energy saving.
At first sight, this looks like a conventional micro-prismatic panel but it has a couple of tricks up its sleeve. The main advantage is that it has a POD socket on the rear which can be used to attach a microwave sensor or an emergency lighting self-test option.
The panel also supports Ansell’s smart lighting system so the Endurance can have added functionality such as daylight harvesting or zonal desk lighting.
Its rated life of L70 60,000 hours and maximum ambient of 40C is higher than most. It is also IP44; most panels are IP20.
This is a backlit panel and one of the most efficient we tested. Visually, it is a lot more interesting because of the Dynamic Aspect™ diffuser. This has alternating concentric squares of opal and prismatic. It is a lot more interesting to look at but most of the light is still concentrated downwards.
If you want a lot of light, there is a 4,400 lm version available and this is 40W.
A slightly wider light distribution and a TP(a) diffuser would make this panel almost perfect.
This side-lit panel is available in 5700K and the more usual 4000K. It has a smooth micro-prismatic panel and a light guide behind, so the result is a uniform appearance across the whole face.
One possible disadvantage is that the maximum ambient operating temperature is 25C. Ceiling voids are often hotter than this.
Integral LED Advance
This slim side-lit panel has a micro-prismatic panel behind a polycarbonate diffuser so it is TP(a) rated and the glare is kept below UGR 19. It has a conventional steel back to aid thermal performance and will operate in a 40C ambient. This is warmer than some other panels
What makes this panel different from some others is that Integral LED has their own photometric laboratory in Aylesbury so they can keep a close eye on the optical performance and quality.
This is unusual in appearance in that it has two rows of LEDs, each measuring about 30 x 530 mm. Each row has 22 individually lensed LEDs set back in a small recess. Its claimed efficiency is higher than any of the other panels.
These produce a narrow downward beam with a UGR of <16. The cut-off is approximately 45 degrees either side of straight down. Beyond this angle you would hardly know the panel was on. In this respect, it is similar to the old fluorescent louvred Cat 1 luminaires.
Whilst outside the 45 degrees it is low glare, the disadvantage is that you have to have quite close spacings between the panels to achieve a uniform illumination in the space.
It’s a solidly constructed panel with quality paint finishes and fine tolerances on all the joins. The rated life is 50 percent longer than some other panels.
This is a backlit panel with much more sophisticated optics than a regular panel. There is a central prismatic panel approximately 300 mm square which suppresses light above 65 degrees (like the old Cat 2 classification). Most of the light output is emitted from this central area. Around this is an opal diffuser which gives softer lighting to the vertical surfaces of the room.
Luxonic refer to this optical combination as giving volumetric lighting. The effect is more uniform lighting on the horizontal and vertical surfaces. Your office will look brighter.
Being backlit, it has greater efficiency, 117 lm/W, than most panels. Also, being deeper, it is much more rigid.
The Sterling is aimed at the contractor and specifier market. NVC has a separate range for wholesalers.
When illuminated, the Sterling is uniform across the whole face and this is due to the micro-prismatic panel coupled with a pmma light guide. NVC claim it is UGR 19 compliant and the lm/W one of the highest.
The whole panel is less than 10 mm thick and a neat aspect of the appearance is that you cannot see a bevelled joint at the corners. Unsurprisingly, it does flex a little bit when you are handling it.
There is a whole range of dimming and emergency versions available.
The data below is as stated by the manufacturers. All panels are 4,000K
- See the latest LED tubes at the LuxLive 2019 exhibition. The show takes place at ExCeL London on Wednesday 13 November and Thursday 14 November 2019. Entry is free if you pre-register. For more info, click HERE