I briefly addressed the subject of LED lifetime last Fall, and have since authored a detailed white paper, accessible here. With the establishment of a new IES standard, known as TM-21, the industry has taken another big step towards one consistent and reliable model for LED lifetime calculation.

What is TM-21? It first helps to understand LM-80, which is the IES-approved method of measuring the lumen maintenance of LED packages and modules. Lumen maintenance refers to the number of hours that a light source remains “useful” before its output diminishes to 70%. The creation of the LM-80 standard ensured that manufacturers were testing for lumen maintenance in a consistent fashion – requiring a minimum of 6,000 hours of testing at various temperatures. The lumen maintenance measurement, known as L70, would then be extrapolated from these test results. However, before the arrival of TM-21, there was no standard basis for the extrapolation, and calculations varied from one manufacturer to another.

Simply put, the TM-21 standard picks up where LM-80 left off. Since LED sources are capable of lifetimes well beyond 6,000 hours, TM-21 establishes a standard way to use LM-80 data to make consistent lifetime projections beyond the testing period. TM-21 dictates which values can be used in the calculation based on the sample size, number of hours and intervals tested, and test suite temperature. It also puts a cap on the extrapolation – a maximum of 6X the hours tested – which eliminates those infamous 100,000-hour claims of yesterday. Since most manufacturers test for 6,000 or 10,000 hours, the accurate range based on TM-21 is up to 36,000 to 60,000 hours of useful life. After this time period, it does not mean the LED will fail; it is just the limit that can be claimed when using TM-21.

While these industry standards have provided tremendous help, there are other factors that must be considered when estimating the lifetime of integrated LED fixtures – vs. the LED packages or modules alone. The design of the fixture is critical, from the drivers and optics to thermal management, in addition to the fixture’s intended application and operating environment.

The bottom line when it comes to LED lifetime is to do your homework and know your manufacturer. Ask about their testing practices and adherence to standards. Those of us in the industry who take great care to deliver quality products with substantiated data will always be happy to answer.

The tone and message at the summit were unequivocally positive – not surprising given that attendees and exhibitors alike have skin in the energy game. But what about the public in general? At a time when federal funding of early stage energy innovation is being questioned, are consumers drawing the connection between these visionary projects and their real-world impact? A report issued by Pike Research the very same week of the summit suggests that this connection must be stronger. In fact, the report indicates that consumers’ outlook on clean energy has become less favorable over the past three years. How do we translate the importance of these big energy ideas to the broader audience? Several key points raised by the summit’s speakers should resonate directly with the mainstream today.

• Jobs, jobs, jobs. Bill Clinton referenced a Deutsche Bank study attributing 300,000 new jobs in Germany to the country’s environmental incentives, and there is no shortage of data on the link between clean energy and economic growth here at home. Check out this chart on the DOE’s website, projecting hundreds of thousands of jobs to come from green non-residential construction alone. But, we must be willing to invest in the sector – including the early stage projects being funded by ARPA-E – to benefit from the jobs and economic resurgence that will follow as commercial winners emerge.

• Timeframe. The results of energy innovation won’t arrive with Apple-like speed. Bill Gates noted, “The IT revolution is the exception that has warped people’s minds in how quickly things work.” For those of us who aren’t scientists and engineers, headlines about far-reaching energy concepts like fuel-producing tobacco plants are merely headlines. Having lived through the IT revolution, we are used to seeing newer, better, faster technology gadgets and are quick to embrace them. But the pace of clean energy innovation and adoption can’t possibly match that speed, and thus consumers should focus on the bigger, longer-term picture.

• Energy Independence. As said by FedEx CEO Fred Smith, “Our dependence on imported petroleum constitutes the country’s largest security and economic risk.” None of us is immune to the consequences of our nation’s dependence on foreign oil, which span from geopolitical concerns, to debate about high-risk oil exploration and production, to fluctuating prices at the gas pump. Energy independence is the ultimate prize for researchers, policymakers, investors, entrepreneurs and consumers alike.

With potential rewards of this magnitude, no idea is “too big” or “too visionary” when it comes to reinventing the energy landscape. Our sincerest thanks to the ARPA-E team for their tireless work to foster innovation in all sectors and expand the conversation so that everyone understands why energy innovations are critical to them.

• The message about saving energy through better lighting is resonating. There was a time when cutting energy use or making the “greener” choice meant sacrifice. The first generation of compact fluorescent lamps was infamously flawed, and ultimately rejected, in spite of the energy savings promised. But energy-efficient light sources, including LEDs, have come a long way, and the DOE report shows an encouraging increase in adoption. Across all applications, the installed base has become more efficient, as measured by the number of Watts used per the number of lumens produced. This suggests that both commercial and residential users have greater confidence to invest in energy-saving lighting, and will likely be further influenced by utility-based incentives and regulations such as California’s Title 24.
• Opportunity abounds to replace inferior technologies in commercial and industrial environments. Linear fluorescents currently reign with more than 80% of the installed base in these two sectors. Despite their high energy use, HID lamps have gained ground in industrial settings where high lumen output is a must. LEDs were formerly unable to compete in these applications, but now can outperform both fluorescent and HID with higher output, better light quality, lower energy use and far less maintenance. Today facilities have the capital budgets, sustainability mandates and financial incentives to upgrade to more efficient lighting systems, and they can expect Digital Lumens to come knocking with an intelligent industrial LED solution that typically pays for itself within two years.
• “Lighting controls equate to energy savings only if they are used.” We couldn’t agree more, and that means that automation is strongly preferred over manual adjustment. Simply put, the Digital Lumens LED lights are more autonomous than fluorescent or HID sources could ever dream of becoming. On top of using highly efficient LEDs, each of our fixtures has the on-board “smarts” to sense and automatically respond to its environment – whether it’s occupancy, available daylight, time of day or other variables – and deliver just the right amount of light — when and where it is needed. Rather than applying controls as an afterthought, we build them right in, and the built-in approach maximizes energy efficiency.

Takeaways from the report? For the industrial lighting customer, new efficient lighting technologies offer a whole new value proposition that includes both performance and efficiency. For Digital Lumens, the golden era of industrial LED lighting is just beginning.

The complete DOE report is available for download here:

http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/2010-lmc-final-jan-2012.pdf

If you already know about FIRST, I’m delighted. If you don’t, here’s a quick overview. Started in 1992 by Dean Kamen, FIRST (For Inspiration and Recognition of Science and Technology) is ‘an organization dedicated to motivating the next generation to understand, use, and enjoy science and technology.’ The program’s goal is to inspire young people to ‘be science and technology leaders, by engaging them in exciting mentor-based programs that build science, engineering and technology skills, that inspire innovation, and that foster well-rounded life capabilities including self-confidence, communication, and leadership.’  A worthy goal and one that the program is meeting every day, with 250,000 participants worldwide.

There are programs for all different ages, starting with Lego-based challenges for younger kids, up through more complex challenges for high-school participants. For the 9^th to 12^th grade teams who participate in the FIRST Robotics Competition (FRC), each receives a kit of materials to build a robot optimized to achieve a specific set of tasks. The teams then compete at the local and regional levels, with those winners moving onto the championship in St. Louis. Teams come from all over the world – not just the U.S. – to compete. Worth noting is that the competitions are structured so that gracious professionalism is strongly encouraged to promote cooperation and support of other teams. FIRST has coined a term for this they call ‘coopertition.’ And let me just say that if you think that a robotics competition is boring or dull, think again. Check out video clips from last year’s FIRST Championship here. The energy, cooperation, enthusiasm, team spirit and community support are positively amazing!

As with most activities, there are some expenses involved, which the teams need to defray, such as travel, supplies to build their robots, community programs, etc., necessitating team fundraising. Clever kids come up with clever fundraising ideas – such as selling parts they design to other teams, or holding concerts, or rating local companies on Angie’s List, or selling items they collect in the community on eBay. And FIRST has created another opportunity for the teams — the sale of LED light bulbs. Girl Scouts sell cookies. Boy Scouts sell popcorn. FIRST teams sell energy-efficient light bulbs – teaching them about sales and marketing, while helping them raise funds for their team. The teams are selling 40-Watt equivalent LED replacement bulbs, which run at 8 Watts, and 60-Watt equivalents, which run at 13.5 Watts (both versions are dimmable to 5%).

As part of the LED program, the FIRST teams receive training material about how LEDs work, and all of the benefits of LED lamps vs. other sources. What better way to educate the public about the benefits of LED lighting then to use FIRST teams who are into science and technology and love to learn about new things? FIRST teams also are required to give back to the local community, which this program facilitates with educational outreach about the value of adopting LEDs. The teams have been very excited because the program is both good for the environment, while supporting their participation in a highly educational program. And the program is doing very well!

In the first 6 months, approximately 50,000 lamps were sold, and this year the program has expanded the offerings. If you’d like to learn more about the FIRST, the LED program, or find a team in your region you’d like to support, follow the links below:

• FIRST Program Overview
• FIRST LED program
• To find a local FIRST team selling LEDs

As someone who is deeply committed to helping the next generation of students embrace science in its many forms, I am a huge supporter of FIRST and devote a large portion of my volunteer time to it. I hope you’ll take the time to learn more about the program, consider LED bulbs for your home and office environments, and consider spreading the word about FIRST and maybe even getting involved.

In a facility with skylights, windows, sidelights, clerestory windows, or the occasional open docks and bays, you have available daylight, which varies according to time of day, weather conditions and more. Areas that get light from those sources don’t necessarily need much artificial light – at least not during the day – but areas farther from those sources do. The problem is in a large site with thousands of square feet of space.  Managing each fixture’s light output to compensate for the changing amounts of ambient light during the day is an enormous challenge and is impossible to do manually.

To date, facility managers trying to take advantage of daylight have looked to external daylight harvesting sensors that attach to groups of lights. These after-market offerings can provide incremental energy reductions, but still leave substantial savings on the table and have a number of performance issues that result in over- or under-lit areas and jarring jumps or drops in light levels. Not to mention that these sensors can be difficult to configure and are prone to implementation issues. Just check search for ‘daylight harvesting commissioning guide’ or for a tutorial on how to set this up and you’ll understand more. It’s high-order math for modest gains.

But there is a better way. It is possible to take full advantage of ambient daylight, manage light levels, and see exactly how much lighting energy is being saved. That is the approach Digital Lumens has taken with its latest additions to the Intelligent Lighting System, which integrate daylight sensing into every fixture. This approach delivers much higher energy savings and improved functionality because each fixture intelligently measures available ambient light and gradually adjusts light output to maintain desired light levels.

Easy to configure and manage, the Digital Lumens daylight harvesting functionality also provides an easy interface for controlling fixtures and reporting on savings. Do you want to know how much money and energy you’ve saved in your facility? That information is readily available. Do you want to change your target light levels? It’s at your fingertips; you don’t need to get up on a lift and adjust dipswitches on sensors controlling 100+ fixtures.

Savings

So how much energy does daylight harvesting actually save? In addition to the energy savings that Digital Lumens delivers by providing light when and where it is needed – up to 90% — daylight harvesting can save an additional 25-50% depending on the amount of ambient light available.

This LightRules chart shows actual lighting energy use (purple area) and lighting energy saved (blue) by the integrated daylight harvesting capabilities in the 18,000- and 26,000-lumen additions to the  Digital Lumens Intelligent Lighting System.

We will continue to delve into daylight harvesting and other savings opportunities in future posts. In the meantime, if there are other topics you’re interested in, please let us know by sending us a note at info@digitallumens.com.

With these new highbay LED light fixtures, we now offer a broad spectrum of outputs from 10,000-lumens to 26,000 lumens allowing our customers to pick the right light for the job.  The higher brightness LED light fixtures are ideal for applications that have wide open spaces, higher ceilings, or intense foot candle requirements.  Like our current 10,000 and 15,000 lumen highbay LED light fixtures, the new offerings have embedded occupancy sensors, integrated intelligence, wireless networking, plus modular rotatable light bars.  The new fixtures have two important enhancements — increased environmental protection (IP65) further expanding the applications to damp locations, food processing, and exterior covered locations — and an embedded daylight sensor.

Like the embedded occupancy sensor available in all of our fixtures, the new daylight sensor is fully integrated into every one of the 18,000 lumens and 26,000 lumens LED lights and software-controlled to provide the perfect balance between performance and energy savings.  Unlike tacked-on sensors available from other manufacturers, the DL architecture has numerous benefits. Because it is integrated, it is less expensive and cumbersome for the customer (no additional installation), while increasing energy savings with granular, per-LED light control that matches lighting to the demands of the business and environment.  The Digital Lumens implementation also provides LightRules reports that show just how much energy is being saved – proving that the Digital Lumens Daylighting saves 25% to 50% more energy than the competition. That information can be shared within the facility, throughout the corporation, and with the utility.  Bolt-on, after-market daylight sensors simply cannot compare – either on the basis of functionality or energy savings to this approach.

Digital Lumens maintains an unwavering focus on saving our customers MORE money.  This drives every decision we make as we continuously enhance the Intelligent LED Lighting System.  Part of this focus is empowering our customer with MORE information and MORE money-saving options, enabling them to direct MORE of their financial resources to the critical parts of their businesses.  Read here for more on today’s announcement on the product line expansion  and daylight harvesting.

MORE light + MORE intelligence = the MOST savings.

Two weeks ago, we welcomed a new employee to Digital Lumens.  Since we have been hiring roughly one employee every two weeks, this was not an unusual event. However, this employee is our sixth who has served in our country’s military — and now approximately 10% of our employees are veterans.

This young man comes to us having served in the Army, and he and his fiancée moved up to Boston from South Carolina (just in time for our recent October snow storm).  Like each veteran we have been able to hire, he brings a level of experience, preparedness, and resourcefulness that is unique to those who have been trained in the services.  Extra bonus – he calls me sir.

There has been a lot of talk these days about the gulf between the 99% and the 1%, with that distinction being drawn on economic grounds. The other gulf that exists in our country is between those who are sacrificing for our nation’s freedom and security and those of us who simply benefit from their sacrifices.  The new 1% are those who have committed a part of their life — and too often have given their lives — for the 99% who are not serving.

And it turns out that most lights in most facilities don’t have to be on 100% of the time – creating a major energy-savings opportunity.  Typically, each light only needs to be on briefly – especially when you figure that the average warehouse has one employee for every 10,000 square feet.  It’s pretty difficult for a forklift operator to be everywhere every moment of the day, so why should you pay to light spaces where your operators aren’t?

And that’s where the many benefits of highbay LED lights come into play.  Unlike conventional lighting sources, LED lighting is immune to the life-cycle reduction problems that plague fluorescents, so they’re easily integrated with occupancy sensors that aggressively turn them on and off based upon local activity.  Intelligently and rapidly turning LED lights on and off saves huge amounts of energy and money – without compromising facility safety of performance or lighting lifetimes.  In fact, LED lifetime is measured in ‘on time’ <link to our earlier blog post on LED lifetime>, so every moment that the fixture is off is another moment of calendar lifetime for the LED. (Worth noting is that conventional lighting, such as fluorescent fixtures, can’t be turned on an off too frequently without greatly lowering the life of the fixture and tubes, as well as potentially violating the warranty.)

But back to occupancy.  What Digital Lumens and our network of resellers mean when we discuss occupancy in industrial LED lighting is what percentage of overall time any one highbay LED light will be on.  For many facilities, that number is 20%.

So, instead of continuing to use the same word for lighting that also pertains to inventory levels, we’ve started using the term ‘Total Lighting Time’ to refer to what percentage of time lights need to be on to support the general activity patterns in a facility.  Does this mean that a facility isn’t busy if we say that occupancy is 20%? No. Just the opposite.  The busier the facility is, the more rapidly the lights will cycle on and off as staff move through.  But because operators are moving quickly through an area, lights cycle on and off, meaning that the lights aren’t staying on any longer than needed. And, as described in ‘Black is the New Green’, the more you can lower the Total Lighting Time by turning off the light, the more money you can save.

In our next post, I’ll dig into how managing settings in the lighting system make all the difference.

When it comes to industrial lighting, facility managers can now control lighting to maximize energy savings – an option that was limited, at best, with traditional lighting sources. After-market controls are available for HID or HIF lighting to save energy – providing the ability to set timeouts, dimming, scheduling and daylighting to maximize “off time” or “dim time”, but often not in combination with one another.  Further, the shortcomings of the underlying light sources – an inability to rapidly cycle on/off without compromising lamp lifetime and, when integrated with even simple controls, the inability to reach necessary light levels quickly enough to insure operator safety – make them less-than-ideal.  Not to mention that the energy reductions are incremental, at best.

There are after-market controls available for HID or HIF lighting that have some nice features and can save some energy, but without them being well integrated with the fixtures, you lose the ability to use all of these features at once and make changes quickly and easily.  Only an integrated solution, with embedded intelligence and an easy-to-use management system, can offer the ability to set timeouts, dimming, scheduling, and daylighting to maximize “off time” or “dim time.”  Furthermore, conventional lighting has several shortcomings – an inability to rapidly cycle on/off without compromising lamp lifetime and, when integrated with even simple controls, an inability to reach necessary light levels quickly enough to ensure operator safety.  And, without the ability to turn the lights on and off quickly, energy savings are incremental, at best.

Highly controllable light sources – LEDs – are the new industrial reality; and integrated, intelligent controls makes possible new levels of energy efficiency.  These lights use much less power to generate excellent light levels, while leveraging controls that light the space only when occupied – you only pay for the light you need.  How? Lighting is provided based on occupancy and required illumination levels, and tailored to your facility’s schedule.  Here’s a closer look at the controls variables that drive lighting energy savings:

• Occupancy levels in cold storage, warehouse and manufacturing environments are often significantly lower than one might expect. Occupancy doesn’t mean how busy the facility is, just how much the average light ends up being on.  In very busy facilities that have the LEDs turning off quickly, occupancy can be less than 10%!  Paying for lighting only when needed creates significant savings opportunities.  Light the area where the operators are; not the area where they were ten minutes earlier.

• Timeouts – the amount of time after an area is vacated – seem insignificant but can have a major impact on lighting energy savings.  Do your lights need to be on for ten minutes after an area is vacant?  Doubtful.  Two minutes? Probably not, but you may want to experiment and find out. We see numerous instances where facility managers start out with conservative, two-minute timeouts and find that they can move down to thirty seconds without compromising operator safety, productivity or comfort.  But, to test this, you need to be able to do this from an easy-to-use management interface, and not on a lift 30 feet in the air.

• Illumination (or dimming) levels provide additional savings opportunities, as well.  When the lights are turned on, are they on at 100% or are they on at a lower level? And, when the lights are turned off, does off mean completely dark?  Maybe.  Off can also mean night-light mode (say illumination of only 10%) in specific locations – cross-aisles and back corners, for example – so a room is never totally dark. Those decisions make a significant bottom-line difference, because, if you need some light, dim is cheaper than fully on.

• Advanced scheduling options provide yet another way to maximize savings.  Does your facility have seasonal changes that your lighting should adjust with? Aligning the lighting delivered with the lighting needed is an essential controls strategy. But, this is only possible with solutions that let you adjust settings easily with a software-based interface. Because we know that it is too much of a nuisance to get up on a scissor lift and manually change settings on hundreds of fixtures.  Use a mouse, not a lift.

Helping facility managers maximize lighting energy savings is what drives Digital Lumens and our product development team.  We recognize that the most successful solutions maximize the green on the bottom line and green from an environmental perspective.  In lighting, the best way to go green is to go black (or dark).  Simply put, if cash is king, then Black is the new Green.

First, here’s the scoop on lifetimes for traditional light sources.  The lifetime rating you see on the side of the standard incandescent screw-in bulb is defined as the number of hours after which 50% of similar bulbs would have failed completely.  This is sometimes called Mean Time Between Failure – MTBF.  The bulb in the package has a 50% chance of failing before that time.  And failing means no light output, of course.  Here’s a look at lifetimes by type:

• Incandescent bulbs can range from 750 hours to 2,000 for “long-life” versions.
• Compact fluorescents (CFL) bulbs have claims of up to 10,000-hour lifetimes.
• Industrial HIF and HID lamps are approaching 20,000-hour lifetimes.   

Remember that these are the time period at which they are expected to fail totally.  And these lifetime ratings assume ideal conditions; rugged applications or lots of on/off cycles reduce the useful life.  Then there is the issue of depreciation (reduced lumen output).  The light from most of these bulbs will depreciate substantially (often more than 30%) within the first third of their lives, often causing designers to overlight spaces to compensate.  This adds to both the up-front costs and lifetime energy cost of conventional lighting applications.

Now onto LEDs.  When we talk about LED lifetime, we mean the period after which the LED light puts out only 70% of its original light. (Note: this is not total failure, just the point at which the system emits less light and a fundamental difference in the definition of ‘lifetime’ largely because LEDs are a fundamentally different illumination technology.)  In technical parlance, this is the L₇₀ rating and can range from 50,000 to 100,000 hours based on design and operating temperature.  Even after that time period, the LED light will continue to operate for years; just not at 100%.

Figure 1:  Typical light output change from for different light sources vs. operating hours. Source: http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/lifetime_white_leds.pdf

Lifetime is an important consideration — many people still recall the lingering ‘bad taste’ that CFLs left in the mouths of early adopters — so buyers want accurate information before embracing LEDs.  And it is an important factor in the economics of an LED purchase.  The Department of Energy has taken a leadership role in ensuring that credible vendors build and certify quality products.  There’s the Energy Star program (for many categories of LEDs), the LightingFacts program (which ensures clear and accurate labeling), and their relationship with the DesignLights Consortium for listing highbay and industrial LED lighting products.  And vendors are stepping up, too, to ensure that customers that adopt LED products have great experience.

At Digital Lumens, all of our products are built with quality and reliability as core design principles.  Each Digital Lumens product is completely UL listed, listed on the DesignLightsConsortium’s Qualified Products List to ease rebate approval, comes with spec sheets that list L70, LM80 and all of the other relevant criteria, and has a 5-year warranty.  We are committed to being one of the first vendors to adopt the DOE’s new Total Luminaire Lifetime Ratings, as well.

So, lifetime matters tremendously in LEDs because they offer unprecedented levels of energy efficiency AND exceptional lifetime, making them a natural choice for your illumination needs.  LEDs have already taken over the traffic signals, cell phone and computer screen backlighting, TV, and automotive lighting, and are poised to capture general illumination over the next decade.

I urge you to learn more about what makes LEDs so compelling and be a well-informed customer.  Ask lots of questions and make sure you are dealing with a reliable vendor and a quality product.  The time is now to seriously consider LEDs for their bright and long life.