Archive for the ‘LED Lighting’ Category

Power LEDs breach 100-lumen-per-watt barrier

Thursday, March 25th, 2010

Philips Lumileds has launched a power LED that exceeds the psychologically important output of 100 lumens per watt.

The company says the Luxeon Rebel ES will make it easier to create solid-state systems that that is more efficient than conventional lighting in applications such as outdoor illumination and refrigeration.

Philips Lighting's Rudi Provoost at Lightfair

Provoost Talking up LEDs at Lightfair in New York

Advantage, lighting designers
Steve Barlow, executive VP of sales and marketing at Philips Lumileds, said the device “meets two complementary objectives: extending the energy-saving ability of LED technology and simplifying LED product selection to make it easier for lighting designers to take advantage of those capabilities”.

Flux binning and forward voltage binning selections for the Luxeon Rebel ES are pre-determined to deliver efficacy of 100 lumens per watt. Designers simply have to choose the colour temperature of the device. Philips says this will speed design and manufacturing, and lower development costs.

LED manufacturing technology
The company says fluctuation of efficacy and light output is minimised with changes in temperature.

The devices are manufactured using Philips Lumileds’ thin film flip chip technology, and the company said the Luxeon Rebel ES benefits from the continuous improvement of epitaxial processes.

Biggest change since electric light
Philips Lighting CEO Rudy Provoost, speaking at Lightfair International in New York, described solid state lighting as “arguably the most profound change the industry has witnessed since the invention of electric light itself”. He said the company was a leader in every part of the solid state lighting chain, “from processors and components to light engines and modules; lamps, fixtures and luminaires to complete lighting systems”.

He added that the recent acquisitions of Lumileds, Color Kinetics and the Genlyte group had “laid the foundation for a holistic approach”, and that licensing of Philips IP portfolio, such as the recent deal with Zumtobel, would “open up the full potential of LED solutions to the entire industry. This will help fuel the growth of the solid state market”.

Top firms unite to standardise LED engines

Thursday, March 25th, 2010

Top manufacturers including Philips, Osram, Zumtobel, Trilux, Panasonic, Toshiba, Cooper, Schreder and Acuity Brands are to unite this month to agree standard specifications for the interfaces of LED engines.

The move is crucial if LED engines in luminaires are to be interchangeable in the same way as conventional lamps.

The companies are forming a new organisation – dubbed Zhaga – in an bid to prevent the fragmentation of the market into incompatible light engines. The Zhaga standards, as they are being called, will cover the physical dimensions, photometrics and electrical and thermal behaviour of LED light engines.

It’s hoped that Zhaga standards will give consumers confidence to specify and purchase LED products because they will know that the engine will be easily replaceable and commercially available. Also, the standardisation of standards should foster innovation and competition in the application of LED lighting in general.

Zhaga membership is open to all manufacturers across the industry including LED light engine makers, luminaire specialists, and suppliers of components such as heatsinks and optics.

LED Solid-State Lighting technology AC – DC Drivers, or direct mains driven (AC-LED) device?

Friday, June 12th, 2009

The increasing strength of a new Solid-State Lighting technology that could eventually take its place alongside conventional LED technology. However, will AC driven LEDs actually displace DC driven LEDs – that is the real question!

The impact of Light Emitting Diodes (LEDs) on the general lighting industry has only just started with tremendous revenue growth seen during 2007 for white LEDs. However the rapid pace of LED development continues unabated in early 2008 with the release of Seoul Semiconductors Z-Power P7 single LED emitter package emitting up to a maximum of 900 lumens from just 10 electrical watts and up to 995 lumens maximum from a 15W device from LEDEngin Inc.


The latest LED emitter packages to be launched onto the lighting market include the new class of AC driven LEDs that do not require AC/DC LED drivers and offers the promise of simplifying LED luminaire design.


The latest LEDs are more efficient, usable and environmentally friendly than CFLs.


At the end of the first quarter of 2008 several manufacturers have launch new LED emitter packages onto the market all exhibiting common characteristics of increased light output, greater efficiency and lower LED thermal resistance. Indeed, these latest “digital” LEDs have now exceeded the raw lumen output of most typical Compact Fluorescent Lighting devices and at a much higher efficacy at much higher levels of light quality and with a lower carbon footprint meaning LEDs should now become the light source of choice.


The P7 Series compared to general 60-watt incandescent lamps, which provides an efficacy of approximately 11 lumens per watt, emits light at up to 900 lumens and has a maximum efficacy of 90 lumens per watt. The colour temperature of the P7 is 6300K meaning that it is only available in cool white and the colour rendering index (Ra) is low at 70. However this lighting breakthrough is happening at a time when oil prices have exceeded $107 per barrel and the environmental waste aspects are fuelling interest for energy efficient systems all around the world.
In addition, the P7 Series shows remarkable performance compared to compact fluorescent lamps with a typical CFL consuming 15 watts and emitting light at 930 lumens delivering an efficacy of 62 lumens per watt, while the P7 Series’ efficacy is nearly one-and-a-half times higher at 90 lumens per watt. Therefore, for the first time a single LED emitter package in a space of only 18.4mm x 12mm x 6.54mm can produce the same raw lumens as a 15W CFL bulb which is pretty impressive!


As known by many in the lighting industry, the maximum performance of a P7 (derived from a manufacturer’s datasheet) should not be used to predict the total system efficacy due to thermal performance in standard operating conditions but even the typical luminous flux for a P7 is rated at 700 lumens providing a typical efficacy of 70 lumens per watt (still better than that of a CFL).  The data sheet gives the total forward current as 2.8A, with forward voltage of 3.6V, so one can assume each chip is driven at 700 mA (or around 2.5W). When the device is driven at 1400 mA (forward voltage = 3.3V), or 350 mA per chip, the typical output is 400lm, corresponding to an efficacy of around 86 lm/W.

The configuration of the LED chips within the P7 is structured so that they operated in parallel, which is rather unusual for two reasons:
1. Running LED chips in parallel without any voltage or current balancing can create uneven current paths that could result in a variety of issues from uneven chip illumination where one LED has more current flowing through it so it has a high lumen output compared to the others through to rapid failure if one LED chip fails because the current through the other 3 LEDs has to take the current meant for 4 LEDs.
2. There is currently very little choice for high current LED drivers especially those that can drive currents up to 2.8A so the industry will need to wait until a large number of drivers become available at these higher currents.

Perhaps, it may have been more prudent to design the P7 so that all of the LED chips were connected in series which would mitigate any of the issues highlighted and would provide a choice of drivers from 350mA up to 700mA. In fact, the LEDEngin LZ4 10W and 15W LED devices have gone one further by providing direct access to each LED chip, within the package enabling the lighting manufacturer to decide whether to control each LED individually, connect them in series or similar to the P7 in parallel.
Although the luminous efficacy of the LEDEngin product range is lower than that indicated by the P7 it offers a smaller package of just 7mm by 7mm and comes in a wide range of colours and cool, neutral and warm white colour temperatures with a CRI as high as 90 as shown in Tables 2 and 3.

Referring to P7 4 chip LED emitter with the equivalent sized single chip emitters there is clearly a significant step change in performance. This performance increase is due to improved LED packaging resulting in a lower thermal resistance of just 3°C/W for the P7 and the LED chips are operated at a lower forward current.
It is clear that the P7 will create a new trend of multi-die, high luminous output emitter packages at affordable costs and it is certain other LED manufacturers will follow with low-cost variants ensuring the rapid deployment of LEDs in general lighting markets.

AC LEDs – What are they?
The vast majority of LEDs sold in the market place are DC driven LEDs however a new class of LEDs that are driven directly from the mains supply are being touted as an alternative to traditional DC LEDs. DC-driven LEDs have several disadvantages including:

  • AC/DC power supplies add extra cost and require more space.
  • Design difficulties to accommodate space and thermal dissipation requirements for DC-LEDs make it less viable as a replacement for conventional incandescent bulbs or building structure lightin
  • Waste materials from the converter causes environmental pollution
  • 80% efficiency of AC/DC converter causes 20% of electricity loss
  • When using an AC/DC converter in small or enclosed area the heat from LED and converter interaction can accumulate heat causing a reduction in lifespan
  • Overheating can cause a fire concern which will require safety plans
  • Cannot be easily configured or linked together in long chains

While the lifespan of DC-driven LEDs sold in the market is 50,000 to 100,000 hours, the AC-DC converter needed for its application to lighting fixtures only has a lifespan of 20,000 hours. The need to change the AC-DC converter several times over the life of the LED is a major shortcoming of DC-driving LED technology, and can limit its appeal for lighting fixtures.
In classic textbooks on electronics or physics it will state all LEDs are DC devices, so how can an LED be driven directly from an AC supply at  220-240V? The answer is fairly straight forward; the AC LED device is actually made up of two strings of series-connected die, connected in different directions; one string is illuminated during the positive half of the AC cycle, the other during the negative half. Thus, the device is essentially non-polar. Since the strings fabricated on the substrate are formed from many p-n junctions in series, the total forward voltage of each string is very high, and approaching the AC mains input voltage.
Therefore, an AC LED must be designed for a specific voltage range and at this stage cannot be interchangeable between say 110V or 220V.
Like any LED, proper mounting to a thermally conductive surface is critical. You’ll also need to be mindful that the leads and traces will be carrying high voltages and so care must be taken for fixture design.
The reason AC LED emitters have not been successful to date is due to several factors including:

  • Not as bright as DC LEDs
  • Not as efficient as DC LEDs
  • Low number of manufacturers so reduced availability and choice
  • Reliability is susceptible to voltage variations
  • Intensity variation with over or under voltage on AC mains
  • Switching frequency is limited to mains frequency (50/60Hz) so not suitable for many applications eg; TV lighting
  • Systems are designed around mains voltages
  • The AC LEDs cannot be dimmed easily
  • Available in only low wattage emitters (<10W)

Due to significant research by two companies, Seoul Semiconductor in Korea and Lynk Labs in the US, several of the disadvantages holding back AC LEDs are now being addressed. For example, Seoul Semi announced in February that their AC LED known as the Acriche, had achieved a lumens per watt efficacy level of 80 lm/W although the system is still only available in 2W or 4W versions.
The high reliability of the Acriche AC LED is shown in figure 5 where 70% of initial lamp lumens is reached after 20,000 hours of operation at a junction temperature of 80°C. Similarly to DC LEDs the lifetime of the AC LEDs increases as the junction temperature decreases.
A second company Lynk Labs offers a range of AC driven technology evolved from a core technology layer called No Return Path “NRPTM” technology. NRP and other AC LED technology has been integrated into Lynk Labs AC-LED devices, assemblies, drivers and system solutions for solid-state lighting applications.

Conclusions
The rapid increase in LED luminous efficacy is continuing unabated and today the total light output from a small 10W LED emitter package is essentially equal to that of a 15W Compact Fluorescent ensuring that it is a matter of time before the LED will displace the majority of conventional light sources. The technical barriers are rapidly being overcome one by one and soon a single emitter package will break the 1000 lumen output in a cost effective manner (eg; <$5).
It is less clear to predict the impact of AC driven LEDs against a market dominated by DC LEDs especially as the technology is still so young however AC LEDs are ideal for applications where LED drivers are impractical to install, quality mains voltages are available and no dimming is required such as signage illumination.
The future will see both AC and DC LED systems co-exist within the general lighting market as both techniques have advantages and disadvantages however as the market has already adopted DC LED systems it will be a significant time before AC systems can claim the number of AC LED shipped.

The year of the LED lighting fixture

Friday, June 12th, 2009

British government LED adviser, Dr. Geoff Archenhold, reports on new government initiatives that will speed up the progress of LED fixtures in the commercial market. Unfortunately, the lighting industry is getting to grips with the start of what seems to be a long recession. However there are significant opportunities that point to success for the near-term future of lighting, one of which is high quality LED lighting fixtures.

2009 is a pivotal year for the lighting industry where traditional lighting companies need to invest heavily in the technology to provide quality light for lighting designers. This may not be an easy task for the larger lighting players as they focus on near-term issues such as how to restructure or close conventional product line rather than invest in developing the next generation of technologies – this is an ideal time for innovative newcomers to make big strides in delivering innovative lighting solutions.

An update on Government legislation and support for new technologies
Unless you were without a TV and didn’t read any newspapers or websites you will have seen the European Union have agreed to finally ban the incandescent light bulb. Although this is a very positive step, it is no doubt a very small one mainly due to the fact that several inefficient or environmentally unfriendly light sources such as Halogens and CFL lamps are essentially left untouched. In my opinion there are many reasons why you have legislation but the key aims should always be to ensure safety (whether its product safety or environmental safety through reduced carbon emissions) and to stimulate an improvement in technology which provides an economic stimulus. Unfortunately, banning the incandescent on its own will not achieve significant gains on either front mainly due to the fact that CFL and Halogens are the main products marketed today. One only needs to go to any of the top five supermarkets in the UK to look at the lighting section to see that it is dominated by CFL’s from two or three companies along with a low cost supermarket own label version.

What does this EU directive actually mean for the Industry?
The EU directive sets minimum requirements for domestic lighting so that from 1 September 2009, high-energy bulbs can no longer be circulated in the EU for use in private households. These bulbs will gradually be withdrawn until 2012. The EU directive defines exactly which bulbs will no longer be able to be sold and when. For example, as of 1 September 2009, there will be no more frosted lamps, except for frosted energy saving lamps (CFLi) with energy efficiency class A. Also light bulbs with 80 watts or more will be banned as of this date.

This new EU directive is part of a package of measures from the EU which aims to significantly reduce the energy consumed by electrical devices. The primary aim of this directive is to protect the environment by reducing CO2 emissions.

It is important to note that these regulations apply to non-directional lamps. Directional (reflector) lamps such as spots will be covered by a dedicated measure at the end of 2009 or in 2010. These new regulations could be an opportunity to start phasing out CFL’s especially those used within directional downlight fixtures where such light sources where approximately 50% of the lamp lumens are lost in the fixture design.

Providing LED fixture manufacturers continue to improve light output quality and consistency then the EU directive will become the first step to banning the CFL’s and Halogens within the next 2-3 years as LEDs become more cost effective especially as they are already proving to be more efficient in certain applications.

What will actually change?

As of 1 September 2009, the first styles of light bulbs (80 watts or higher) will disappear from the shelves. Every year after that, in steps of twelve months, further bulbs and wattages will be affected by the ban. By 2012, all light bulbs of greater than 7 watts will be withdrawn from sale except for certain special applications such as ovens or fridges, traffic lights, infrared lamps.

Also halogen lamps with the efficiency class D will be gradually phased out step by step according to their watt and lumen value from 2009 until 2012.

An update of the lamp energy label (Directive 1998/11/EC) is also planned in 2009 in order to redistribute the energy classes after the phasing out of classes D, E, F, G and also to integrate low voltage lamps and reflector lamps, which are currently not covered by the label.

Energy Savings Trust – Starts a 2-phase LED Lighting trial
As part of the UK Government’s £400m Environmental Transformation Fund (ETF) setup in April 2008 and designed to bring forward the development of new low carbon energy and energy efficiency the Energy Saving Trust (EST) has secured funding for LED-based project over the next three years. The first of these projects are the planned field trials of LED lighting technology in communal areas of social housing to begin before April 2009.

The attraction of this type of housing is that the lighting is on 24 hours per day, 7 days a week resulting in high energy costs with traditional lighting and considerable potential savings using LED technology.

A previous study undertaken by the Lighting Association for Aberdeen County Council concluded that the new LED products were suitable for installation in the dwellings, replacing either fluorescent or incandescent lighting yielding several benefits such as reduced energy consumption, reduced carbon emissions and reduced maintenance costs.

The new ETF/EST field trial will seek to install LED lighting in a number of communal housing locations throughout England and the phase 1 locations have already been selected.

The first phases of this field trial are important as there are over 4 million dwellings in England owned or managed by Local Authorities (including ALMO’s and RSL’s) and Housing Associations. This represents approximately 26% of the English housing stock so is a considerable market for LED lighting companies to focus upon.

The interest to participate in phase 1 of the trial was substantial with more than 110 housing managers and over 30 LED companies requesting further information.

In Phase 1, the Energy Savings Trust will fund up to a maximum of 80% of the costs of the proposed replacement LED fittings and has a total fund size of ~£350,000. Expressions of interest to take part in Phase II trials (a much larger trial) will commence in April 2009.

The sites will be fully monitored before, during and after the installation of the LED replacements so that a complete and robust case study for each site can be published in the future. This will be one of the first times data in the UK will be published by an unbiased source and so will provide a good comparison between conventional and LED equivalents in certain applications.

In addition, the Energy Saving Trust will be adding a performance requirement for domestic LED lighting into the EST’s lamp specification version 6. The first three classes of LED lamps to be endorsed under ESR are:

• Mains voltage reflector lamps such as GU10 replacement lamps ie; 240V and power equivalents to a 20,35 and 50W halogen having a minimum life of 25,000 hours.

• Low voltage for incandescent reflector lamps such as MR16 lamps ie; 12V 20, 30 and 50W LED equivalents having a lifetime in excess of 25,000 hours.

• External LED luminaires to replace typical 250W and 500W Halogen floodlighting.

the work EST are undertaking is vital and exactly what the consumer and lighting industry need. Quality and unbiased performance data on LED fixtures and supporting innovation through the ESR programme.

Further information and presentations on the EST LED initiative can be downloaded from www.nwda.co.uk/photonics

LED efficiency is continuously improving
The leading manufacturers are continuing to rapidly improve production LEDs enabling high efficiency LED fixtures to be developed. For example, both CREE and Lumileds have single-die LED products that are readily available with minimum luminous flux that are approximately 100 lumens per watt.

It is clear that there is not much between the leaders of LED manufacturing except for the Warm White Colour Temperature range where Cree has an obvious lead today.

Importantly, there will be some changes during this year and Philips are working on a new technology that is incorporated into the manufacturing of LEDs which will not impact on the total light emitted from an LED die but will significantly improve the efficiency.

It is clear that excluding the great LED improvements will continuously see White LEDs approach the 120 lumen per watt mark at 350mA in the next year which is a significant increase in performance.

In terms of fixture design, this means less number of LED’s are required for a given light output and the thermal management can be much simpler making the heatsinks for the LED lighting smaller which also increases flexibility and reduces cost.

Further improvements of LED dies are continuing at pace in the R&D world and recently Researchers at Rensselaer Polytechnic Institute (RPI) have developed and demonstrated a new type of LED with significantly improved lighting performance and energy efficiency. The research shows that a polarisation-matched LED exhibits an 18% increase in light output and a 22% increase in wall-plug efficiency compared to currently constructed LEDs.

Importantly, the new LED device achieves a notable reduction in ‘efficiency droop’, a phenomenon that allows LEDs to be most efficient when receiving low-density currents of electricity, but then to lose efficiency as higher density currents of electricity are fed into the device. Essentially, this type of new research would enable LED manufacturers to build LEDs that are highly scalable in terms of driving them at higher forward currents whilst still maintaining the lumens per watt efficiencies. Current LEDs can lose up to 30% of the increased light output when they are driven at 700mA rather than 350mA. This research will help LED manufacturers make up the 30% loss when driven at high currents.

Further Fixture Level Improvements have just a significant role to play as LED emitters in the latest high quality LED fixture design. Today, thermal management is one of the most important system design issues so any new technologies that come along which can reduce the issue enables improved performance.

Once such new technology is graphite PCB’s which can replace the more commonly used Metal Core PCB (MCPCB) adopted by the high power LED industry. Strictly speaking graphite PCB’s are not new technology and they have been used in military applications for many years however their costs have made them rather exclusive in application. However a new Taiwanese company, Polo Tech, is now marketing graphite PCBs (GPCB) for the LED industry.

The new GPCB contains 99.5% graphite and offer a thermal conductivity greater than 400w/mK which is better than most MCPCB’s. Another advantage of GPCBs are they are very lightweight with a density of 1.5 g/cm3. The improved thermal performance means that more heat is transferred from the back of the LED to a heatsink potentially reducing the junction temperature of the LED die and so improving performance and efficiency.

Remote Phosphor Technology – the potential and pitfalls
LED technology that is starting to penetrate the current LED marketplace known as Remote Phosphor Technology (RPT). RPT was first pioneered in the LED sector some nine years ago but it was researchers at the Lighting Research Centre, Rensselaer Polytechnic Institute in the US that provided a practical way forward. They developed and patented a new packaging method for white LEDs called Scattered Photon Extraction (SPE) which enables higher luminous efficiency by placing the phosphor at a remote location from the die by shaping the lens surrounding the die to extract a significant amount of the back-scattered light from phosphor before it is absorbed by other components within the LED emitter. Even back in 2005, the SPE technique showed a 20-25% improvement in efficiency compared to standard white LEDs which was an incredible feat considering how bright LEDs have become in four years!

The most popular way to create a white LED is to use a Blue LED chip which is coated with a phosphor and there are several common methods used in production as shown in figure 2. Referring to figure 2, the majority of LEDs are created using either (a) or (b) where the phosphor is either conformally coated around the LED chip or dispersed throughout the coupling medium respectively. Conformal coating is considered the better technique as the quality of light output is improved and there is less of a CRI or CCT variation with beam angle.

Philips Lumileds have recently developed a new method, Lumiramic, mentioned in previous articles where the phosphor is placed within a small disk above the die to improve quality and consistency.

The first iterations of remote phosphors placed the phosphors away from the LED chip but still within the emitter package. Although this showed an improvement there would still be significant issues with LED temperature especially as phosphor efficiency and lifetime degrade as the ambient temperature increases.

A further issue is that when blue light which is absorbed by the phosphor it converts the light into a different wavelength commonly know as phosphor conversion. Unfortunately, phosphor conversions scatters light in all directions (not just forwards) and hence studies by the Lighting Research Center (LRC) have shown that up to 60% of the lighting created by the phosphor is scattered back toward the LED die and lost due to absorption.

Even when there is a highly polished reflector used the arrangement did not show much of an improvement in terms of extracted light output over traditional packages where the phosphor was placed close to the die. The LRC uses the SPE technique to extract the back-scatter light from the remote phosphor before it is absorbed by using a secondary optic that efficiently transferred the blue light to the remote phosphor whilst recycling the back-scattered white light from the system so it is not lost.

The SPE technique shows a 60% improvement in light output and efficacy compared to similar commercial white LEDs, where the phosphor is placed close to the LED die. Although this research was undertaken in 2005, when traditional white LEDs had an efficacy of 30 lumens per watt at 350mA, the SPE system showed an efficacy of approximately 50 lumens per Watt. If we applied the SPE or similar light recycling techniques to the latest blue LEDs we would be looking at efficiencies of 150-160 lumens per watt!

More recent studies by the LRC indicate how the CCT of an SPE fixture varies with different phosphor densities.

The variation in phosphor density and thickness is one of the key issues for RPT based white LED fixtures hence why manufacturers have taken a long time to begin to introduce such products to the market.

There are several research groups around the world that have been working on RPT technologies where they have mixed two or more different phosphors together enabling a variable colour temperature or CCT to be achieved by using the relative intensities of two different wavelength LEDs. One company that has commercialised this into a product (KPT of Korea) and it has impressed all that have viewed it.

The early-to-market RPT products such as the Philips Fortimo and the much advertised alphaLED products need to be effectively tested for CCT and CRI consistency between fixtures and their lifetime and performances monitored especially if they are using standard blue LEDs illuminating a single phosphor plate.

It is very difficult to ensure the phosphor materials are placed across a 25mm to 100mm plate with a homogeneous density and consistent thickness. If either of these variables change significantly then the CCT and CRI of the light fixture will vary and although it is possible to replicate one or two samples for research it is much more difficult to scale up for higher volumes.

This said, the possibility of significantly improved white LED luminaire efficacy and lifetime which certain remote phosphor technologies have shown, paves the way towards the 150 lumen per watt LED fixture using today’s LED technology.

It will be a matter of time before high quality, consistent and efficient RPT LED fixtures will reach the market with the majority of research required being in the production capability of producing thin consistent layers of phosphor on plates.

The LED fixture manufacturers need to be honest

One of the largest issues that the LED industry needs to face in 2009 is the misleading use of data on specifications sheets. Every time I speak with lighting designers they say that they are constantly being disappointed by LED companies that claim a certain light output and fixture efficacy but when they see the technology it falls way too short.

The main issue is that most of the LED manufacturers quote LED lumens on their datasheets that does not account for thermal degradation, optical efficiency or LED efficiency. For example, I see many specification sheets that claim a fixture with 9 White LEDs can produce 810 lumens ie; 9 x 90 lumens minimum = 810 lumens. Then the manufacturer will state that the fixture takes, for example, 12 watts of power so that the fixture luminaire is ~70 lumens per watt which is totally misleading.

All LED fixture manufacturers to state realistic and actual operational figures on their datasheets so that the industry maintains a professional standard. There is a call for the UK Government to adopt a strategy similar to that employed by the Caliper programme in the US which tests commercially available lighting products and compares their actual performance against their datasheet stated performance. This way we are able to name and shame organisations that set out to mislead purchases!

Despite this plea, we will see LED fixtures accelerate into the general lighting market and system costs will drop as the new technologies in R&D filter through in one or two years!