Fardin – Page 9 – LED Journal

Lighting

Lighting Controls: Decisions, Decisions

Fardin Posted on July 1, 2018

So we’ve made the decision…..we’re converting the parking deck to LED lighting. Considering the money saved on the energy bill, along with the lower maintenance costs accompanied with not putting someone on a bucket truck for the next 10 years to swap out a bulb, it was an easy call. Now the difficult question; do we also add controls to optimize the lighting system? And if we do want controls, where do we begin? What will work for our parking deck?

Do We Need Controls?
The first question might not be whether or not we want to implement lighting controls, but whether or not we need to implement them. Depending on the location, the state or municipality may very well require basic lighting controls to meet ASHRAE 90.1 requirements (or Title 24 compliance in California). The overall intent of these standards is to ensure that, as a society, we are minimizing unnecessary energy expenditures, as determined by these governing bodies. The goal is to reduce energy consumption per capita, which is often achieved through regulation. The first step is to know whether we’re actually required to have a control system. Keep in mind, this broad range of standards covers retrofits as well as new construction.

Do We Want Controls?
The next thing we have to ask ourselves is whether we want controls to manage our lighting system and to what degree. In our world of high technology, embedded systems, and mobile devices, we have a plethora of choices to make when deciding exactly how we want our lights controlled. When evaluating lighting control systems, they fall into two categories: Sensor Networks and Services.

Sensor Networks
Sensor networks deploy strategies for minimizing our energy bill, namely occupancy detection and daylight harvesting. Nothing new here, but the decision-making comes into play in how sophisticated or intelligent we want that sensor network to be. Basically, our options are as follows:

System A: One-Way Communication

A car enters the parking lot, tripping an occupancy sensor
Sensor sends a control signal to a group of luminaires, declaring occupancy in the space
Luminaires increase light output to safely illuminate the occupant’s path
Occupant exits the area, causing the sensor to enter a state of non-occupancy, dimming the lights accordingly

In this scenario, the only system feedback we receive is a reduction in our energy bill. But if our budget is tight, and we simply want to enjoy enhanced energy savings while complying with regulations, this approach will do. If we desire more information from our system, then we’ll want System B.

System B: Two-Way Communication

A car enters the parking lot, tripping an occupancy sensor
– Sensor records and timestamps the event
Sensor sends a control signal to a group of luminaires, declaring occupancy in the space
– Luminaire(s) sends acknowledgement to the sensor that the message was received
Luminaires increase light output to safely illuminate the occupant’s path
– Light output measured and recorded
Occupant exits the area, causing the sensor to enter a state of non-occupancy, dimming the lights accordingly
– Sensor records and timestamps when system moved back into non-occupancy state
– Occupancy events, power consumption, occupancy duration, etc. tracked and sent to central control unit for data processing

From the occupant’s perspective, System B’s functionality is identical to that of System A. The value of the data is to us, as the owner, because we now have metrics telling us whether our investment is operating as intended. We can also determine traffic patterns from the system data, including when the parking lot is being used, and how much energy the lights are consuming. Using this basic information, we can further configure our system to minimize energy consumption, while ensuring the space is safely and securely illuminated for our patrons.

Whether we choose a one-way or two-way (data feedback) communication network, we need to consider the protocol. Essentially, the protocol a system utilizes is the language executed to communicate between devices (sensors, controllers, light fixtures, etc.). We have two protocol choices; 1) an open protocol (e.g. DALI, ZigBee, etc.), which allows devices from multiple manufacturers to communicate on the same network, or 2) a proprietary protocol, which is typically exclusive to a single manufacturer. A network using an open-protocol is attractive from a competitive price standpoint because we have multiple controls vendors from which to choose. The advantage of a proprietary protocol is that each device on the network was designed and tested to be compatible, so we can be confident in the communication and performance of the system. Since a proprietary system is from a single manufacturer, we only have one phone call to make if we experience a system malfunction.

Services
This is where lighting gets fun. The lighting industry is experiencing a renaissance as it comes to grips with a convergence of technologies beginning with the LED. LED luminaires present two distinct advantages over traditional lamp options: 1) the light source is a semiconductor, which provides for easier integration into embedded systems, and 2) its location. Since data can now be provided by the sensor network, we can take that information and send text or email alerts to maintenance personnel, notifying them of a system disruption. Once that email alert is received, maintenance can locate the specific luminaire on a virtual lighting layout via their internet browser. And speaking of location, luminaires can also provide application-specific services to parking patrons. With intelligent lighting (located everywhere) we can track available parking spaces in a structure or lot, creating efficient notifications to inbound customers looking for an open spot. But why stop there? Once parked, why not deploy a mobile app that guides patrons from their car into the facility and back again once their visit has concluded? In essence, our lighting system can act as a local satellite network, providing services unique to a particular application.

Conclusion
The lighting landscape has changed, there’s no longer a simple answer as to whether we want lighting controls. We now have to ask ourselves a series of questions:

Do regulations require I purchase lighting controls?
Do I want my system to provide data?
Are email and text alerts important to my operation?
Are there other services I can provide with my lighting system?
What support or warranty does the lighting control manufacturer provide?

The last question is critical. As the industry grapples with the technology shift, an unprecedented number of start-ups are jumping into the fray with warranties longer than the lifespan of the company. Remaining diligent in vendor selection and asking a few probing questions can lead to a beneficial controls solution that will positively impact our monthly cash flow—saving energy while providing a unique experience for the customer. When we show a friend our new smartphone, we delightfully talk about its apps, camera quality, user interface, and so on. The conversation then ends with, “and by the way, it makes pretty good calls too”. We’ll soon talk about our lighting features in a similar manner…and by the way, the quality of light is pretty good too!

Energy

Update on the New Energy Star Lamp Standard Process

Fardin Posted on June 29, 2018

Just prior to the start of Lightfair, the EPA released Draft 4 of the Energy Star Product Specification for Lamps. The intent of this effort is to harmonize and update the CFL and LED lamp standards into a unified specification for omnidirectional, decorative, and directional replacement bulbs such as A, G, PAR and MR styles for example. This effort has been going through the stakeholder review process since October 2011 and seems to be approaching completion. Once approved, there will be a one year transition process to phase in and replace the existing Integral LED Lamp (V1.4) requirements.

Since requirements seem to be finalizing, now seemed like an appropriate time to highlight some of the requirements specifically related to LED bulbs that are changing, discuss new requirements that are being added as well as indicate some of the items that are being carried forward from the existing Integral LED Lamp eligibility requirements. Moreover some requirements are being relaxed or expanded in scope. Since the standard is still in a draft state, these items are still subject to changes based on stakeholder feedback. A webinar going over the changes will occur on May 13^th with final stakeholder comments due by May 17^th.

The table above while far from exhaustive, does highlight some of the critical parameters. Not surprising based on the rapid improvement of LED lamps is that the minimum efficicacy requirements have inched up. One of the items that has harmonized with the CFL requirements is the addition of a wider gamut of CCT (Correlated Color Temperature) options so now “cooler” 5,000 K and 6,500 K have been added, but all LED lamps must still have a minimum CRI (Color Rendering Index) of 80 with a R9>0. Interestingly only a 7 step MacAdam ellipse is required, which is still considered a wide window compared to existing incandescent and halogen bulbs.

One surprise for some LED bulb manufacturers is that the option to submit non-standard bulb shapes has been eliminated. This reflects in some way the fact that LEDs, optics, thermal management and drivers are capable of achieving the minimum lifetime requirements without the need for extra space for larger heatsinks or room within the bulb for drive electronics that was an early limitation of some lamps. Unfortunately this decision also eliminates line powered MR16 type lamps with a GU10 base since that is currently not in the existing ANSI standard.

One area where the requirements have been enhanced is the area of dimming performance. While there is no requirement that LED bulbs be dimmable within the specification, for those bulbs that want to claim to be “dimmable”, there are some tangible requirements that must be meet. First they must be tested with at least 10 dimmers from at least two different suppliers. At the minimum dimmer position, at least 80 percent of the lamps tested must have a light output of < 20 percent. Moreover at the maximum position the stated light output must be at least 80 percent of the stated lumen requirement for the bulb when directly powered from the line. Make no mistake, these dimming requirements in no way imply comparable performance to incandescent or halogen light sources, nevertheless for the first time, there are established some rudimentary boundaries conditions. While this is a far cry from requiring manufacturers to design their LED lamps to comply with recommended NEMA SSL-6 dimming curve it is a step in the right direction and reflects in may ways the challenges associated with making LED bulbs backwardly compatible to all the phase cut dimmers that have been installed across the North America over the last few decades.

One area that has been added to the specification is a new flicker requirement based on a concept called the flicker index. As anyone involved in the lighting industry knows, all lamps powered directly from the AC line including incandescent, fluorescent as well as LEDs have frequency dependent luminous flux variation and depending on the magnitude and frequency may have physiological impact to individuals who may be particularity sensitive so this is not a new phenomena. While there are complex analytical tools to quantify optical flicker, it is also possible to see it with graphical tools such as this tool below provided by Lumenique.

Flicker Indicator Machine (Image Courtesy of Kevin L. Willmorth, Lumenique)

In the case of integral LED lamps, the main contributor to optical flicker is the design of the LED driver and since there are numerous driver configurations with various design, performance and cost tradeoffs, this topic can be quite complex and will be covered in a future article. In the mean while to get additional information on the topic of Flicker, the Department of Energy recently published a technology fact sheet on the subject that is very informative.

LED

The Flexible Definition of High Brightness LEDs

Fardin Posted on June 24, 2018January 19, 2021

Shortly after the first transistor was invented some talented folks had the idea of crafting several on the same piece of silicon and the integrated circuit was born. A few more transistors were added and the integrated circuit was renamed the Large Scale Integrated circuit, then the Very Large Scale Integrated Circuit, then the industry ran out of adjectives and concentrated instead on putting 4bn transistors on a chip. So it is with the LED industry, where the definition of ‘high brightness’ is somewhat flexible, depending on whether the conversation is about LED die, light engines or luminaires.

Most LEDs emit visible light, with much of the current focus on the development of white LEDs to replace tungsten and fluorescent lights in general illumination. A white LED that is 100 percent efficient would run slightly north of 400 Lm/W. Modern high brightness LEDs are rapidly approaching 40 percent efficiency, meaning the remaining 60 percent comes out as heat. Unless this heat is removed, the LEDs will fail faster than you can say “tungsten filament” and a major part of developing LED lighting products is in devising effective thermal management solutions.

Of particular importance to the thermal management of LEDs is the substrate or circuit board to which the semiconductor components are attached. High brightness LEDs are physically small, usually measuring less than 0.5 mm on a side. This means that not only does a significant quantity of heat need to be removed but, more importantly, the thermal flux, which is the quantity of heat per unit area, is intense. Consequently only a limited selection of materials are suitable for this application since candidates must possess the combination of low thermal resistance and good dielectric properties. Tiles made from ceramics like aluminium nitride and beryllium oxide are technically superb but very expensive, while metal-in-board PCBs such as those based on Nanoceramic coated aluminium can provide similar thermal performance at a fraction of the cost with the added benefits of physical robustness, availability in large panels and 3D profiles.

It should be noted that the definition of “high brightness” is also influenced by the wavelength of the LEDs. Aside from visible LEDs there is a rapidly growing industry, currently worth around $100m/annum that manufactures LEDs to emit UV radiation. These are used in all manner of industrial processes from disinfection and sterilization through plant growth, printing to scientific instruments. A key difference with white LEDs is that UV LEDs are incredibly inefficient. A “high brightness” UVC LED might only be 5 percent efficient. In other words, these LEDs are actually high power electrical heaters and produce the odd photon every second Tuesday. Not only do UVC LEDs produce significantly greater heat than white LEDs, to make matters worse the small light output means the LED die have to be packed extremely densely in order to achieve acceptable optical output. In this industry, it is not uncommon to find UVC LEDs that are operating at power levels of 150 W/cm². To put that figure in perspective, a COB domestic white LED ceiling down lighter is running at about 5 W/cm², some 30 times lower.

For these high brightness UVC LEDs, the approach to thermal management is completely different. Rather than a heat sink to dissipate the heat to air, the LEDs are mounted on a water-cooled metal block, held at constant temperature by an industrially-sized chiller. Between the LEDs and the cold plate there still needs to be a circuit board to provide electrical connection to the LEDs. All organic materials are excluded since they would be rapidly destroyed by the UVC radiation. Thus the choice reduces to metallized ceramic plates with their attendant economic and physical limitations or Nanoceramic coated aluminium, which, with a bit of ingenuity, can incorporate water cooling channels.

Efficiency gains probably mean that the next definition of “high brightness” in the context of white LEDs will not have to resort to water cooling. Nevertheless, it is comforting to know that thanks to the UVC LED industry the thermal solution has already been proven and the required materials and components are available off-the-shelf, today.

LED

LED Industry Outlook and the Shift in the Value Chain

Fardin Posted on June 22, 2018January 19, 2021

Promising higher luminous efficiency and service life, environmental friendly LED lighting is revolutionizing the $110 billion dollar lighting industry. With more than $25 billion dollars in sales last year, the LED industry is around 11 percent of the size of the computer market, and is still growing. As a relatively nascent industry, it can be hard to predict and understand the LED industry by itself, but by comparing it to the more mature computer hardware market as well as understanding the particularities of the LED market, we can get a good idea of the current state of the industry and its future outlook.

In certain ways, an LED luminaire parallels a desktop computer; A complex finished product is assembled from components designed by various manufacturers, contractors and suppliers. Both are driven by semiconductor processes and just as Moore’s law has for years predicted growth in CPU and memory performance, improvements in transistor density and manufacturing have driven LED performance and continue to improve luminous efficiency.

But not everything is the same. Whereas the computer industry is monopolized by relatively few established brands, the LED industry is more of a green field market with a large number of players. Sales from the top LED lighting brands Philips, OSRAM, Panasonic, General Electric, Acuity Brands, Zumtobel, Toshiba, Cooper Lighting, Cree and Hubbell combined account for less than 30 percent of the market share in the lighting industry. The majority of the market space is occupied by smaller vendors and opportunities are ripe for companies with unique offerings and innovative business models.

GlacialTech makes the following outlook statements and development forecasts for the LED lighting industry:

Price competition in the LED lighting industry will become fiercer, especially in the LED package segment.
LED packages are made through the semi-conductor process and just like CPUs are driven by Moore’s law, but unlike the CPU industry which is almost monopolized by Intel, the LED manufacturing industry is much more competitive with several leading brands as well as a number of regional suppliers, Price competition in the this segment means LED package prices will continue to decrease while performance continues to increase. We expect that the price to performance ratio of the most efficient LED lighting modules will be $0.13/W by the end of the year, and the price of LED lighting modules with performance of 150 lm/W will drop to $0.10 /W or below by the end of 2016.

Value will shift from the LED lighting unit to the driver and thermal module.
The cost of a lighting module for a 100W LED luminaires will be around $10 by the end of next year. For the same 100W mid and high-end LED luminaires, the cost of the thermal modules or LED driver will be double or even triple that of the lighting unit. This is because compared to LED lighting packages, the cost of thermal modules and LED drivers is much more inelastic. Being dependent on the cost of raw materials and manpower. The cost of materials is almost constant unless the price of raw materials changes. There is seldom a huge rise or fall. In addition, the manufacturing process is still quite labor-intensive and involves complex manual procedures, whereas the LED package manufacturing process is increasingly automated.

Gross profit margins of LED lighting modules will continue to erode compared to others parts and components.
LED packaging requires high capital and human investment compared with LED driver and thermal design. To establish a packaging house, high capital costs are needed to procure equipment, and high operating costs are needed as well to compensate the diverse array of professionals required to design highly efficient products and control production quality. In power or heat sink industries, on the other hand, just a few senior design engineers are enough to design effective products with a high price-performance ratio, and therefore staffing costs are relatively low. The equipment used to manufacture LED driver and thermal module is often less specialized. If this equipment was already been used to manufacture other products over the years it may already be fully depreciated.

The COB package has a promising future.
Considering costs of materials and the continuous improvement of COB quality and efficiency, sales of COB packages will continue to rise in the following years, especially as the compact COB form factor is suitable for more LED luminaire designs than larger MCPCB packages. There are already 100W, 200W and even 300W COB LEDs on the market these days making it is easy for luminaire manufacturers to make a 100W~300W (system efficacy 100+ lm/W, CRI 80) lighting products with just one powerful COB coupled with a high quality lens, thermal module and power-efficient LED Driver. The material cost of this new kind of COB powered luminaire is lower than that of traditional LED luminaires in which multiple LEDs on a large MCPCB were used. In addition, assembly of these COB luminaire is simplified, leading to lower manpower costs.

Vertical integration will occur in price competitive segments while specialization will occur at the premium lighting product segment
In the lighting industry, bulbs and tubes are relatively low-priced, making them suitable for vertical integration to improve profit margins. Low-priced and competitive products should be manufactured with fully automated process at one production facility, from the LED package, to plastic injection, metal press, assembly, all the way through to the final packing process. Premium lighting products such as luminaries with differentiated designs and specialized applications may not be able to efficiently improve the price-performance ratio of individual components to make the products more competitive. Hence, companies involved in the premium product space benefit less from vertical integration and can consider specializing in their product segment to maximize profits and market share.

While big name brands own a large share of today’s LED market, there is high growth potential in this industry and plenty of opportunity for emerging companies with innovative technology and unique products.
Thanks to the abundant array of high quality LED package suppliers, luminaire manufacturers have many choices. With the development of COB LEDs, luminairecompanies can build a finished product with barely more than a thermal module and LED driver with appropriate control mechanisms. This is why more and more new companies continue to join the industry in addition to world-known brands and regional brands. Just as innovate technologies and business models pushed the computer industry from big mainframes made by a few big brands to PCs manufactured by myriad smaller companies, the LED industry will continue to mature. The next generation of LED lighting will be driven by forward thinking businesses able to see market trends and take advantage of the latest technologies to drive industry growth.

We have described the current status of the industry and made the forecast above. However, each company which finds its own position in the same environment and selects the appropriate business model can generate higher economic profits than its competitors.

Lighting

Dimming Control Solutions for LED Lighting Systems Using CCRs

Fardin Posted on June 18, 2018

The migration from incandescent and fluorescent lighting to the lower power, longer lifespan alternatives offered by modern LED technology continues at a frantic pace. Research firm Strategies Unlimited predicts that, due to the greater energy efficiency and extended operation of LED emitters, the solid-state retrofit lamp market will be worth more than $3.7 billion by the year 2016. The possibilities are not just limited to general illumination – as more sophisticated digital signage and decorative lighting systems are now seeing widespread deployment, taking advantage of the high degree of versatility that LED based lighting can provide. However, if this huge market growth is to continue and new application areas are to be exploited, engineers must be totally assured that the LEDs specified into their lighting system designs can cope with the harsh environmental or operational conditions they could potentially be exposed to.

The incandescent lamp, with its resistive light element, masks changes in power. Power spikes and surges will often have no immediate effect, as the slow response of the element absorbs the spike, with little or no change in light output. However, the life of the element is decreased due to the extra power being absorbed. Solid state lighting tends to respond immediately to any small change in power and thus spikes or surges will be seen as a higher pulse or flash of light. The LED driver circuit must thus be designed to handle these changes in power, so that they do not impact the light output or the life of the circuit. In addition, engineers need to be able to specify component parts that will not impinge on the systems economic viability in an increasingly price-sensitive market.

A vast number of different lighting dimmers are now found on the market, and there is a great deal of difficulty creating a power control solution that will work with all of them. Normally the control systems needed for this task rely on the use of cumbersome discrete and passive components. There are a number of major drawbacks with this approach though, namely:

The components involved will exhibit relatively high power consumption.
They take up considerable board space and impinge on the form factor of the system.
The total bill of materials resulting from their use can be high and potentially prohibitive.
The development of such systems can often be complex and time consuming.

These issues are causing lighting design engineers to explore highly integrated solutions, based on more sophisticated power semiconductor technology. Advanced linear constant current regulator (CCR) devices can present engineers with a more reliable and cost-effective method for regulating the level of current passing through LEDs than is possible via conventional methodologies.

Key Aspects of CCR-Based Lighting Control
Engineers developing solid-state lighting control systems need to consider how to keep the power factor (PF) as high as possible, while trying to ensure the total harmonic dispersion (THD) is kept low. In addition, so that economies of scale can be satisfied, the voltage range should be broad so the design can be applied across multiple geographic regions, while not having to sacrifice either the THD or PF too significantly. This is a very difficult balancing act – as design teams have to take into account the price points and the efficiency levels that will be acceptable in different parts of the world. In developing countries, the priority will be keeping the cost low, while elsewhere (such as in Europe or North America) compliance with environmental legislation will mean that efficiency levels are critical to the overall design.

The LED dimming circuit described in Figure 1, which is based on CCR operation, enables a marked increase in power efficiency levels and lowers the overall bill of materials. It is capable of working with a wide variety of different dimmers. The circuit makes use of three CCRs from ON Semiconductor based on proprietary self-biased transistor technology. Two NSIC2050 120 V rated devices which can deliver a steady-state current of 100 mA, and a single NSI5010 CCR to limit the power consumption of the triac dimmer.

Figure 1. Low Cost Lighting Circuit based on CCRs with Dimmable Interface

The circuit can be broken up into two separate sections:

LED management – This takes the AC and converts it, by charging the output capacitor, to produce a DC state.
Dimmer Management – This provides loading current for the silicon controlled rectifier (SCR) within the dimmer and delivers a gate voltage to the series pass MOSFET. The gate drive of the series MOSFET pulse width modulates the LEDs at their peak current rating. The two NSIC2050 CCRs provide over-current and over-voltage protection to the LED emitters, while the NSI5010 CCR limits the power consumption of the dimmer management circuit. It synchronises the operation of the led to the signal coming off the TRIAC.

For optimal performance, the gate voltage of the MOSFET (driven by the voltage divider of the 11 kΩ and 1.5 kΩ resistances shown in Figure 1) needs to correspond to the threshold voltage when the input voltage to the circuit is at the minimum conduction angle.

The self-biased transistor found within each of these CCRs is preset by design for a suitable current in the fixed current devices, or a small current range in the adjustable devices (the current being selected through the use of an external resistor). These devices have built-in voltage surge suppression and negative temperature coefficients. They are capable of providing full over-current and over-voltage protection to the LED emitters while only requiring inclusion of a minimal number of external components.

The CCR’s temperature sensing ability allows it to make use of a negative temperature coefficient to automatically stabilize the current as it warms up due to power dissipation. The CCR turns on immediately and is able to provide 25 percent of the set current with a voltage of only 0.5 V across it. This allows the LEDs to be activated virtually as soon as power is applied. Regulation begins at about 1.8 V and remains stable up to the maximum voltage of the device.

By utilizing advanced CCRs like the ones discussed here, based on innovative self-biased transistor technology with a high degree of functionality integrated onto the chip, it is possible to support vulnerable solid-state lighting systems design against extreme levels of ambient heat and high voltage spikes as well as deal with the key ‘board level’ issues effecting the design. The system design elements will include enhanced system performance, ensuring long-term operation, lowering the total bill of materials, reducing board space utilization and shortening the overall development time.

LED

LED ROI – Assessment Metrics with Lumens Per Dollar Over Warrantied Life

Fardin Posted on June 16, 2018

To date, Return on Investment (ROI) has been a guiding force in the adoption of commercial LED technology. If a $100 fixture saves $33 each year, the ROI is naturally 33 percent. If the LED fixtures earn a utility rebate that is either based on a prescriptive amount like $25 or a performance amount on the reduces annual kilowatt hours, the net hardware cost could come done to $75. Given that the installation labor may come in around $25 per fixture, the rebate often offsets a major portion of the installation, holding the ROI in this example to 33 percent, or a 3 year payback. Paybacks in three years or less are favorable, especially since the LED fixture may last for a decade. The rebates are a key aspect of the ROI, and many utility companies use the DesignLights Consortium (DLC) for their Qualified Products List (QPL) to determine eligibility on a fixture by fixture basis.

ROI is a very valuable assessment metric, but it does not address long term value when comparing one or more LED fixture to other options. Light output, measured in lumens, has been a performance metric in the lighting market relative to power consumption, measured in watts. The lighting industry has largely used lumens per watt (lm/w) as a guiding metric to determine fixture value. Lm/w is similar to miles per gallon (mpg) for vehicles, but it does not take into account cost. When buyers consider purchasing a car, the fuel efficiency is typically relevant, but mpg is only part of the decision relative to the total cost, features, and warranty on the vehicle. Lumens per dollar is a way to link the output of the light to the cost, and lumens per dollar over the warrantied life is a guide to determine lifecycle value and Total Cost of Ownership (TCO).

Lm/$ over LED life and TCO are strong sibling metrics in addition to ROI. You could have an ROI “winner” for fixture “A” that is a lower cost LED fixture, but if it has lower lm/w and a shorter warranty than other options “B” or “C”, it will actually cost more over time to operate and maintain. Think of LED fixtures as energy tools vs product commodities in assessing a new purchase.

Steps for Energy Intelligent Assessment of LED fixtures:

Open a spread sheet
Get the Specification Sheets for the LED fixtures that you are reviewing
Use the spread sheet rows for each LED light
Use the spread sheet columns as follows to enter the data (from left to right):
A: Manufacturer Name, B: Product Number, C: Lumens Output, D: Watts, E: Warranty in Years, F: Product Cost
Run the calculations in additional columns for each LED light:
G: Lumens/Watt, H: Lumens/Dollar, I: Lumens/Warranties Life, J: Lumen/Dollar over Warrantied Life

Given equal aesthetic appeal, functionality, installation cost, the winner should be easily apparent in the column with Lumen / Dollar over Warrantied Life.

LED

Will US Made LED Fixtures Ever Cost Less than Chinese Imports?

Fardin Posted on June 14, 2018

The answer is YES. Today, some US LED manufacturers have already “cracked the code” on beating the Chinese at price, while maintaining high quality. This may be surprising to many business owners, energy advisors and lighting professionals. In a presidential election year, candidates on both sides of the aisle have spoken about the benefits of increasing US manufacturing and the resulting job creation. Domestic manufacturing alone does not create economic growth if the products that are produced are not competitively priced and purchased by consumers.

The formula for competitively priced US made LED fixtures is based on several key factors:

LED Automation: We have to work smarter and not harder. The Chinese labor costs are far below the US costs. So, automated technology “labor” combined with select human labor for quality assurance is key for cost control. We can also engineer the LED fixtures in modular ways to integrate with automation more cost-effectively.

LED Shipping: The “landed” cost with the US Customs cost of imported goods are surprisingly higher than most consumers would image. By making products in the US close to population hubs, like the US northeast corridor, Chicago, Los Angles, etc. the domestic products can shave off dollars that add to the cost of the Chinese imports. For large size fixtures such as warehouse high bays, the shipping cost from half way around the world is often a larger percentage of the cost than something like socket bulbs that replace the Edison lamps and Compact Fluorescent Lamps (CFLs).

LED Niches: The Chinese LED manufacturers are typically focused more on mass market volume than custom niches. So, there are “riches in the niches” for American manufacturers. As an example, there is some demand for protective impact cages on gymnasium lights at schools where students playing lacrosse may use the lights for target practice…against the wishes of their coaches. Needless to say, a high speed lacrosse ball can do significant damage to a metal halide, fluorescent, or LED light. The demand for impact resistant LED gym fixtures is much less than the mass market demand for many other types of lights. The Chinese have focused on the volume over the specialty fixtures, so their costs go up dramatically if they have to engineer a specialty application and interrupt a production line to make it. This photo is an example of an impact resistant LED high bay that is lower in cost than Chinese imports both with and without the cage. The apples to apples metric for evaluating cost is Lumens per Dollar, and this fixture wins the day.

Efficiency and TCO: The output of light relative to the energy consumed (lumens per watt) is also the default metric for comparing products. If a US made fixture has a higher lm/w than an imported fixture, it may be due to more advanced thermal management or more advanced and expensive diodes. If that is the case, the fixture will cost less to operate every month. It may cost a little bit more upfront but save more money over its life. The Total Cost of Ownership (TCO) may be lower with the US made LED fixture. Just as lm/w is a key factor in determining the lowest TCO, so too is lumens per dollar. Not all fixtures in the same “category” have the same output, so make sure to also compare what you get (lumens) for what you spend (dollars).

Warranty and TCO: Lumens per watt and lumens per dollar have a third sibling in determining the lowest Total Cost of Ownership (TCO) – Lumens per Dollar over the Warrantied life. The length of the warranty is key, as is the coverage in the warranty language. If a Chinese LED fixture has a 5 year warranty, and a US fixture has higher quality components, better thermal management, and higher overall quality controls in the manufacturing process, then the total output in lumens will far exceed the import across the life of the fixture. Time is money, so if you do not have to spend the time re-installing a fixture in five years or buying a new fixture in five years, then the US made fixture just got a whole lot less expensive than the import.

Top Tip on LED Price Comparison: If you are in the market to change your existing lights to energy saving LED fixtures, or if you have new construction projects then take a careful look at the Lumens per Watt, Lumens per Dollar and Lumens per Dollar over the Warranties life…and not just the price of the fixtures. If you are an Electrical Contractor or Value Added Reseller (VAR) providing lighting solutions, then make sure to compare the prices and the warranties, beyond just the length of the warranty coverage. If you are a lighting designer or architect, take a hard look at US LED manufacturers before making an assumption that US products are more expensive than imported Chinese LED fixtures.

Lighting

Lighting Must Continue to Lead…

Fardin Posted on June 14, 2018

Two years ago, I closed a guest blog post in this very space with the following: “….exciting times and opportunities lie ahead for lighting that leads…” (see “Tipping Points, Toothaches and LEDs” published on 4/9/2013). That two-year old blog post hinted of evolutionary opportunities available to/for “lighting,” something I referred to as “lighting that leads.” Some likely thought my speculations/thinking were too far afield for “lighting,” but clearly there were/are those who thought/think similarly. Recently, numerous lighting companies, including OSRAM SYLVANIA with our new LIGHTIFY portfolio, have made announcements about connected lighting. Recognizing that sockets compatible with connecting lighting heretofore only served to hold and power a source of illumination, it is remarkable to realize that those same sockets are also now physically and technically positioned to enable intelligent receiving and transmitting nodes in a “connected world,” indeed to become an integral part of the coming Internet of Things/Everything. Remarkable!

Knowing that light and lighting are ubiquitous and a mainstay in our 24/7 culture, one should not be too surprised to discover products and technologies which facilitate the production and delivery of light might also be an important part of the “connected world’s” infrastructure. Said differently, I believe products and technologies which facilitate the production and delivery of light will have the first right of refusal in becoming a critically important part of the coming “connected world,” particularly in ways which are very visible to the average consumer. To me, this is both obvious and concerning. Done correctly, I believe this will provide service, application and business opportunities for companies who have long-served consumers of light and lighting products. I expect said companies will have opportunities to participate in new growth and profitable business areas which have been difficult to find and take benefit of in recent years. In addition to the growth and profitability opportunities, I do have concerns related to the challenges the former “lighting companies” have in accommodating the dramatic change in expertise and competence required to design, develop and support “connected” products, technologies and services. Having said that, lighting companies, once known only as experts in traditional light sources and/or drivers/controls, are embracing the opportunity to change their technological core, to evolve and reinvent themselves toward connected technologies, products and service, while maintaining their competence and expertise in providing light and illumination. I believe the trend and direction of the players, and the industry, is favorable.

Although I view the current situation as favorable, I believe many challenges remain. Despite those challenges, I stand by my closing comment of nearly two years ago – – – – The work will be challenging, but interesting. The benefits will initially be difficult to document with numbers, but nonetheless evident. Patience (by all) will be required but exciting times and opportunities lie ahead for lighting that leads!

Energy

How Recycled Energy Waste from LEDS can Make Horticulture More Efficient

Fardin Posted on May 29, 2018

One of the often-cited advantages of LEDs over tungsten filament and fluorescent lights is their high efficiency. A good quality white LED can convert around 40 percent of the electrical energy to light. While this sounds impressive when compared to other light sources it still means 60 percent of the electricity is wasted as heat. Of LEDs that work in the visible spectrum green devices are the least efficient, maxing out at around 20 percent, while UVC LEDs struggle to achieve double figures.

The heat produced by LEDs has to be removed by conduction. Failure to do so gives rise to problems with the quality of light produced and operational lifespan. The conventional solution is to mount the LEDs on a metal PCB and use a suitably large heat sink to dump the heat to the atmosphere.

Greener LEDs, Greener Flora
A new and rapidly increasing opportunity for LED lighting is in horticulture. While we all know that plants need light to grow (with the possible exception of mushrooms), scientists are just beginning to understand how to tune the light spectrum through a plant’s lifecycle to alter factors such as growth rate, crop yield, color and even taste. Some scientists have even predicted LED lights used in this manner will trigger a revolution in horticulture. Perversely, one of the few wavelengths plants do not respond strongly to is green, so the poorer efficiency of 560 nm LEDs is not an issue in this application.

Installing banks of LEDs in greenhouses and sheds might seem like a good idea until the electricity bill for the first month arrives. High brightness, tunable spectrum LED lights are expensive to run, particularly when lit 24×7. But light is not the only energy requirement. Many plants grow better when cosseted and in particular when the roots are kept warm. So not only does the plant growing space need to be expensively lit, it needs to be expensively heated as well.

Electricity-to-Lumens Conversion Does Not Mean Efficiency
When talking about LED efficiency lighting engineers always talk about conversion of electricity to lumens — with good reason because lights need to produce light! However, when you look at system efficiency, LED lights are 95+ percent efficient if you define the outputs as light and heat. Therein lies a stroke of genius. LED lights need to be cooled and the plants under the lights need their roots to be warmed, so why not use water to cool the LEDs and pump the warm water through pipes in the soil?

This approach has multiple advantages. Water is a much better cooling agent than air so manufacturers can make LED lights smaller, lighter, cheaper and more intense. The bits of the plant that need to be snuggly and warm are provided for and the requirements for insulating and air conditioning the growing space are greatly diminished. In one stroke, the system efficiency has leapt from unacceptable to brilliant. All the waste heat from the LEDs is recycled in the factory, rendering it eminently green.

With any new technology, the early adopters tend to be high-value products where the risk can be offset by the potential financial reward. Therefore, it’s likely to be a few years before you can buy a supermarket lettuce grown under LED lights. However, should you be partial to the occasional leaf of hippie lettuce, purely for medicinal purposes and only legal in certain jurisdictions, then the product will quite possibly have been grown under LED lights. Cool huh?

Blog

Simple Test Reveals the Origin of Efficiency Droop

Fardin Posted on May 23, 2018

GaN-based LEDs find widespread applications, but they exhibit maximum efficiency only at very low current. The electrical-to-optical power conversion efficiency drops dramatically with higher input current. This so-called efficiency droop has been investigated for many years, and it still represents a key challenge to solid-state lighting, according to the DOE SSL R&D Plan published in May 2015.

Trouble is, we often don’t know for sure what causes this efficiency droop. Different microscopic mechanisms have been proposed, most prominently thermionic electron leakage from the light-emitting active layers and Auger recombination inside these layers, respectively. Droop analysis is mainly based on modeling and very few direct measurements of either mechanism are published thus far.

The first direct evidence for Auger recombination in InGaN quantum wells was provided only two years ago by measuring high-energy (hot) electron emission from the LED surface (http://arxiv.org/abs/1304.5469). The authors believe that these hot electrons are generated by Auger recombination inside the active region and subsequently travel all the way to the LED surface. Another experiment was conducted independently by German researchers based on the assumption of a much shorter hot electron travel distance (http://epub.uni-regensburg.de/28841/2/ApplPhysLett_103_071108.pdf). In that case, hot Auger electrons release their energy quickly and are captured by a neighboring active layer. However, the Auger signal is relatively weak in both cases and there is no direct evidence that the Auger process is strong enough to single-handedly cause the measured efficiency droop.

Electron leakage was first observed in 2008 on ultraviolet LEDs by measuring additional light emission from p-doped layers, which indicates electrons traveling beyond the active region. A few similar reports followed, but none was able to demonstrate a leakage magnitude that fully explains the measured efficiency droop. Interestingly, a group from Korea observed electron leakage when the LED is cooled down to cryogenic temperatures (http://dx.doi.org/10.1063/1.3703313). The blue LEDs used in this study did not exhibit any leakage at room temperature. This result was quite unexpected since we usually believe that higher temperatures make it easier for electrons to escape from the active region.

Advanced computer simulation was recently able to explain this phenomenon (http://www.nusod.org/piprek/piprek15apl2.pdf). Due to the high ionization energy of Mg acceptors used for p-doping, rising temperatures free more holes and improve the hole conductivity significantly. This was confirmed experimentally by a group from Finland (http://dx.doi.org/10.1109/TED.2015.2391117). As a result, the hole injection into the active layers is enhanced, fewer electrons need to leak out to find holes, and the efficiency rises with higher temperature.

On the other hand, if Auger recombination is causing the droop, the simulations show a declining efficiency with higher temperature. Thus, the competing efficiency droop mechanisms have the opposite effect on the efficiency when the LED temperature rises. The temperature sensitivity of the LED efficiency therefore offers a simple way to distinguish between both droop mechanisms. Published measurements commonly show a declining efficiency with higher temperature. Thus, Auger recombination can be considered the primary mechanism behind the efficiency droop in these devices.

In fact, I am not aware of any efficiency measurement that shows the opposite trend, i.e., a growing efficiency with rising temperature. Please send me an e-mail if you know of such a case (piprek@nusod.org).