U.S. Department of Energy - Energy Efficiency and Renewable Energy
Building Technologies Office
High Efficiency Troffer Specification Webinar (text version)
The Pacific Northwest National Laboratory (PNNL) held a Webinar presenting an overview of DOE's High-Efficiency Troffer Specification by a cross-cutting project team from DOE's Commercial Building Energy Alliances (CBEA). The Webinar reviewed the energy-saving benefits of high-efficiency troffers, highlighted their design and implementation considerations, and identified different troffer types.
Below is the text version of the Webinar titled "CBEA High-Efficiency Troffer Specification," originally presented on October 25, 2011. In addition to this text version of the audio, you can view the presentation slides and a recording of the Webinar (WMV 16 MB).
Welcome, ladies and gentleman, I'm Linda Sandahl with the Pacific Northwest National Laboratory, and I'd like to welcome you to today's webcast: Commercial Building Energy Alliances High-Efficiency Troffer Specification, brought to you by the U.S. Department of Energy.
We're happy to have as our speakers today, Michael Myer and Jeff McCullough of Pacific Northwest National Laboratory. Jeff McCullough is a senior research engineer with Pacific Northwest National Laboratory. His main area of focus is commercializing energy efficient technologies, particularly lighting and HVAC systems. He led the development of the first ever ENERGY STAR criteria for Solid-State lighting, and most recently completed the Lumen Maintenance Test Facility, which tests submissions of the L-Prize competition.
Michael Myer is a lighting designer who's been with Pacific Northwest National Labs for about four years now. Prior to that, Michael worked as an architectural lighting designer in New York. Since joining the lab, Michael has worked on a wide range of lighting projects. He currently splits his time between the Federal Appliance Standard Solid-State Lighting Commercialization and the Commercial Building Energy Alliances.
During today's presentation, Michael and Jeff will review the energy saving benefits of high-efficiency troffers, highlight they're design and implementation considerations, and identify different troffer types. The presentation will conclude with an overview of the CBEA troffer specification, which is technology neutral using fluorescent or LED sources, and targets 20% energy savings over typical florescent lamps while maintain good lumen output, distribution, and color quality. After the presentation, questions that were received online will be addressed by the speakers as time allows. Jeff McCullough, please begin.
Good day, everyone, this is Jeff McCullough with the U.S. Department of Energy Pacific Northwest National Laboratory. Also on the phone with me is Michael Myer, also from PNNL. We welcome you to today's webinar entitled: Commercial Building Energy Alliance High-Efficiency Troffer Specification Webinar. We thank you for your attendance today; we're going to move through the slides here slowly.
Here's what we'd like to talk about. We know that troffers are a very interesting energy savings potential, they're ubiquitous, there are literally millions, and one might argue billions of them out there, and until most recently they've been utilizing, for the most part, florescent light sources, florescent lamps. So what we'd like to share with you today is a specification developed by the Commercial Building Energy Alliance that attempts to set a performance threshold and drive the market, and we'll talk about that in more detail as we move through it.
So today's topics, first we'll start with what is the Commercial Building Energy Alliance? I suspect many of you have not heard this term before and so we'll explain what that is and who is involved. It will be important to know what the installed base is. Like I said, there are literally millions of these products out there, but we have some data that's somewhat dated, but we'll share it with you nonetheless so you get a sense as to what products are out there and what their configurations are. We'll go through what is the anatomy of a troffer, what makes these things up, what makes them tick, what are some of the design considerations that we need to think through as we begin specifying these products, and then also installing them. The CALiPER program, CALiPER by the way stands for Commercially Available LED Performance Evaluation and Reporting. That's a DOE program where we actually go out and purchase products in the open-market, test them by independent third party test labs, and then make that data publically available, and so we're going to draw on some of the data from that particular effort. The specification itself will follow. I'll share with you the approach and how we arrived at some of the numbers and the why's that we've set some of the thresholds at the levels that we have, and then the next steps. One of the things that I should share with you is that the specification presented today is still a draft document, so we are inviting your comments and your feedback, and I'll share the details on how to respond at the end. And then there will be a Q&A, a question-and-answer period following the presentation. We'll go for about 30 minutes I suspect. We won't be able to answer everybody's calls or notes, but nonetheless we'll do our best to do that. And one of the things that we get often asked during these presentations is where will the slides be posted? The answer is they will be posted on the CBEA, the Commercial Building Energy Alliance website. We'll provide that link towards the end, so please don't ask us that question because we'll provide it right off the bat.
Okay, let's move forward. So what are the Commercial Building Energy Alliances? And as you can see here, there's a spattering of large logos that I'm sure you recognize. You've got everything from a Wal-Mart to a Home Depot, Cleveland Clinic, MGM Resorts; these are large volume, very large building owners who are interested in saving energy in their own facilities. And I want to make it clear it's not widgets that they would sell or market, but specifically saving energy in their own facilities, so it's a partnership between these Commercial Building Energy Alliances with the Department of Energy and its National Laboratories to help guide research and encourage and drive new technologies going forward.
What are the CBEA goals? So as I stated prior, in the prior slide, informal, they're informal associations amongst the building owners and operators who want to reduce energy consumption. Several of the activities that are undertaken are sharing based, you know we share best practices, how to measure end use energy, we do benchmarking, so it's basically an informal association where building owners can share information, some of the competitiveness, as you can imagine, goes away, and it's simply building owners that have similar concerns and similar needs. They come together to advance the business case for energy efficient buildings. You'll see here in a couple of slides that the membership is actually - - or comprises a fairly large percentage of the installed building base, so they are large volume, high energy using entities that would benefit from energy-efficiency reductions. They deploy advanced technologies. It should be no surprise to you that today's energy climate that reducing energy use through new and innovative approaches is of interest to these organizations, so they are driving those through some of these specifications. They also hope to bring some level of economy of scale to purchasing, to driving the cost down for some of these newer technologies.
So let's take a glimpse at the National Energy portfolio, so there are 5 million commercial buildings that comprise approximately 82 billion square feet of floor space, and commercial buildings account for approximately 18% of the energy that's consumed in the United States. A similar number for greenhouse gas emissions, and just to put things in perspective, that is slightly less than the entire energy economy of India, so that's a very large energy sector, And you can see why it's of interest to DOE and these building owners to reduce that signature.
Here's a breakdown of where the energy goes, so this is a 2008 breakdown of primary energy consumption end uses. You'll see there that the industry is about 31%, transportation about 29%, and the remaining 40% is buildings. Of the buildings sector, about 50% is residential and 50% is commercial, so 22 and 18% respectively for residential and commercial.
What we're interested in today is talking about lighting. Lighting is the largest end use energy segment for the commercial sector, comprising about 21, almost 22% of that entire sector, so it's a very large segment, and hence the reason why we're interested in making some substantive gains in reducing that signature.
Okay, so I shared with you that these alliance members, and let me just explain to you that there are three subgroups of the Commercial Building Energy Alliances. One is the Retailer Alliance, one is the Commercial Real Estate Alliance, and the third one is the Hospital Alliance, so there're actually three subgroups. And you can see by these three pie charts the number of members and the square footage that their facilities take up. So for retailers it's about 54 members, about 2.8 billion square feet. Commercial Real Estate, these are large volume developers and building owners that you can envision would either lease space or would be a developer for spaces; 61 members, about 4.5 billion square feet. And of course the Hospital Alliance are the medical hospital type facilities, 49 members and about a half a billion square feet.
Okay, so why a troffer specification? I hope that we've answered at this point the why now. Clearly there's a lot of interest, there are new technologies, specifically Solid-State lighting that are now approaching being directly competitive with Incumbent Technology, and actually in some cases can surpass Incumbent Technologies. And what was exciting about the specification is that it actually cross-cuts all three of the alliances, retail, commercial real estate, and hospital, all three use troffers in one form or another. The specification itself is supported by utilities and energy-efficiency programs. We'll talk later about some of the voluntary programs that are using at least variations of this current specification, and so we'll talk about those.
It's important that you understand how we arrived here. Back in November of 2010, the alliances came together, we formed a subcommittee that looked at specifically 2'x2' troffers and so that launched the effort. At that time, 2'x2' troffers there were just say two or three new products in the market that were high-performers, and so that's what kind of brought the committee together. That there are these new products, we have an opportunity to set a specification targeting these higher-performance - - higher-performing products, and so through a series of review and comment cycles, the final specification was completed by May of 2011. Meanwhile, in 2011 a great number of new products entered the market. Not just 2'x2' troffers, but we saw manufactures offering 1'x4', 2'x4', and in some cases other troffer or down light type products, some 1'x1's, some 1'x2's, some various products like that. So manufactures began developing suites of troffer products that were high-performance or Solid-State lighting based. And so rather than staying just stagnant with just the 2'x2' troffer and recognizing that there not only were a great number of new products entering the market, but the performance of these new products frankly was quite exciting. They are pushing the envelopes, and in many cases are exceeding even some of the best florescent options that are out there. So based on that information, in August of 2011, the alliance and DOE decided to expand the 2'x2' spec to envelop 1'x4', 2'x2', and 2'x4', and that's what we're presenting to you today, is that melded specification.
So this is just a collage of some of the new products that are out there. I suspect some of you will recognize these, I'm not going to go through and name them by manufacturer, but if one simply does a search on Solid-State lighting troffer, SSL troffer, or LED troffer, you can see there are a significant number now of manufactures now offering these products. We're not saying that they're all equal, but nonetheless there are a great many new products that have entered the market just recently that have been driving the need for this specification.
So let's look at the size of the market. And before I go into some of the numbers here, I do want to point you to the caveat that you see, the cross if you will. I assume there's probably a term for that; I'm not familiar with it. Unfortunately the market, whether it is NEMA or a census data, no longer tracks luminaire manufacturer production numbers. It was very useful back in the '90's, but for whatever reason they no longer do that, so you do need to take this information with a little bit of a grain of salt. We've had, what, 11, 12, years of moving forward, and in some cases, and I'll point them out, I would argue that these numbers are probably not representative of the shipment or the market today. But nonetheless they're helpful for us to understand how big market troffers consume, and then what ratio or what proportion the various sizes encompass. So the top table shows us out of the florescent market, type 1 recessed, those are troffers, both air and non-air handling troffers consume or are 51% of the florescent market. The rest of them, strip lights, wraps, industrial, etcetera, compose the rest. But a full 51% of florescent luminaires are troffers. Now, if I take that information and then I breakdown type 1, which is all the troffers, and I look at what size of troffers would comprise that 51%, a full almost 75% are 2'x4'. And you'll see there that I've got percent type 1 recessed, and then percentage of the florescent market, so it's 38% of the florescent market is a 2'x4' troffer. Okay, 16% are 2'x2' and 8% are 1'x4'. The others, and as you can imagine there are other flavors of troffer, you can have probably some of the older products that are out there, I've seen 4'x4' products, as I said earlier there's 1'x1', there's 1'x2', and you might use a lot of pin based CFL type lamps and those products. So for our purposes of course, we're capturing arguably 98% of the troffer market by this specification.
Now what becomes challenging for us, and as you can imagine we've made attempts of what are the energy consumption and therefore the energy savings via the specification. As I think most of you are aware, troffers come in many different lamp configurations, specifically 2'x4' products can have one, two, or sorry, two, three, or four lamps. There may be some applications where there is one, there may be some applications where there are more lamps, but for the most part, you can see that at least based on 1998 data that 48, sorry, 46% of the luminaires had four lamps. This is where I cry foul. My kneejerk, based on being in the lighting industry for a number of years now, is that given 1998 data, a lot of things have happened, and I'll go through them here quickly. So I'm arguing that the data has probably outdated based on 2011 shipping shipments. So I think we're all aware that energy codes have steadily decreased the lighting power density, so codes have been driving down the watts per square foot, and that of course is it would drive you where you normally put a four lamp troffer, maybe you'd go down to a three or a two. The IES and some of its recommendations have decreased not only illuminants requirements, but also have done some things to address the AGNI*. I mean there are all kinds of things in the new handbook that have changed, the illuminants requirements, and so I would argue that those have decreased overtime as well. Also, new troffer designs have entered the market. We've got all kinds of new volumetric or high-performance type products. We have new lamps and ballasts. You've heard terms like Super T8, T5, and those types of products. We can get ballasts now that are - - where you can increase the light output by virtue of a greater ballast factor, you can decrease the light output by virtue of a lower ballast factor. You can make those with higher output lamps or reduced wattage lamps. You've got a number of permutations out there that are available to specifiers and end users. So again, I argue that this slide or these numbers are probably dated, but nonetheless, I hope that I've built the case that certainly they are a large percentage of our installed base of products, and that the energy savings potential is immense.
So without going into - - and you can just imagine that would be a fairly difficult calculation because we just don't know the number of lamps that are out there and the various ballast and lamp ballast combinations. So if you do just kind of a napkin calculation and assume about 10 and a half hours per day of operation, you know the range of outputs, again, this is driven by the lamp ballast combinations, the number of fixtures, DOE estimates that they're about 63 terawatt hours per year consumed by troffers. A huge, huge number and this is the number that DOE is targeting by virtue of the specification.
At this point I'm going to hand over the presentation to Michael Myer. Michael is a lighting designer, has been heavily involved in standards and test procedures and rule makings, and he's going to take us through the next few slides talking about what are troffers and what are the design considerations when we work with troffers. So with that, Michael, take it away please.
Thanks, Jeff. So the anatomy of a troffer sounds like a much more laborious idea, and we're not going to break through all the different parts of the actual construction, but I really wanted to just start with the overall idea. When we talk 1'x4', and 2'x2', and 2'x4' specifically, what are we really saying? And I think this slide does a pretty good illustration where each tile is representing a length, and so you can see the 1'x4', versus the 2'x2', versus the 2'x4' in an actual graphical comparison. And it's important to understand that the length kind of tells you how it fits into the ceiling or your geometry of it, but the length and times the width is the area, and roughly is the luminous area of the source, luminous area meaning essentially the source of the portion of the fixture that is actually emitting light. Now obviously the entire surface area is not entirely lighted, but it is a good approximation. And it's important to understand these relationships that the small compactness of the 2'x2' limits some of your options. It limits in lamping options, but it also limits it in terms of brightness and some of the glare control things you need to do because as the overall size gets smaller and you keep pushing out more and more light, you're moving from an acceptable luminaire into more of a glare situation. And so that's one of the limitations on the technology. And 1'x4' has similar issues in that the cross section, you know it's only one foot wide, and in many cases we call them 1'x4's but as Jeff indicated, they can also be, I've seen 10 inch, 8 inch, and then you can even get into 6 inch, but usually you get into very specific architectural details at that point. But a 1'x4' also has problems in that because of the angle in which you can view it it's a small cross section, even though it is long, and again you have some of the glare issues. Also, it's a not a lot of room, surface area, room to work in, and that can limit some of your options. Those are three quick comparisons of the luminaires.
As Jeff said, we do a lot of benchmarking. We like to know where we've come from so we can figure out where we're going. This is a great slide of data mining that we've done on 1'x4' troffers. We've done a fair amount of data mining on 2'x2' troffers, and we're also doing additional data mining on two foot by four foot troffers. We're focusing on conventional troffers, and when I say conventional I mean non LED, and we're focusing really on florescent. It could be a linear florescent or a compact florescent or a bent florescent lamp, those are the type of lamping options that we're looking at for any of the troffer benchmarking that we've done. They do make metal high light troffers, and I've actually recently seen an induction troffer, but those are definitely not in the mainstream and so we did not focus on those.
What is interesting about the 1'x4' troffers that we look at is, you know we first segregated it by the number of lamps, then we also looked at it and separated it by the number - - the actual light source type versus T8 versus T5, and we did remove the T5 high output because it was skewing some of the data. While it is a one lamp T5, the high output is definitely much more light than a single lamp, and so it was skewing the data. But what's interesting to note is that as you go down from top to bottom, the optical efficiency, which just means the amount of light that leaves a luminaire, divided by the amount of light generated by the light source combination, goes essentially down. So as you increase the number of lamps, you're actually getting less light out optically. So that's interesting to note is that because you don't have enough room to design a reflector around, or again because of the glare issues, or some thermal effects, there's different things happening, and that's actually causing a reduction in optical efficiency, which leads to a reduction in luminaire efficacy, which is the last column. So you can see that in your one lamp option of either a T8 or a T5, you're in the high 70, 60's to 70 lumens per watt, and then second you go to two lamps you've dropped already. And so this is definitely a design concern with 1'x4' troffers. And the other thing I'd like to point out is that if you notice when you go from the one lamp T8 to the two lamp T8, you're not doubling the light, you're only really getting about a 30-to-40% addition in light output. And so that's significant, you're putting in twice amount of power but not getting out twice amount of light. And so these are some of the challenges that we've noticed in the troffer technology, and we think it's right to hopefully - - for some new technology to come about to fix some of these challenges.
Again, Jeff mentioned the term air handling. And this is a good thing I wanted to touch base on. Again, this is another limitation on the data because since you no longer attract luminaire information, this is technically now 20 years old data, but it is a good benchmark that in 1991 about 75% of the 2'x4' recessed luminaires were static. That means that there's no air movement in and out of the luminaire. We have limited data about the current troffers. And just what an air return does is it allows heat to go through the luminaire, and actually can allow some of the heat from the luminaire go into the plenum and in case you don't know the term plenum, that's just a space between the actual ceiling and other structure. And so air handling is definitely an important aspect for different environments, in healthcare or health related areas they have requirements where they don't want air infiltration to deal with disease mitigation and other mitigation. But in terms of office lighting, it can actually be used to affect the HVAC load or there was actually a paper that actually showed that the performance of the florescent system got better. But it is definitely something to think about when we were looking at the specification.
Continuing on, glare is definitely something that needs to be addressed. I've mentioned it a couple of times in the issues related to the design and construction of a troffer, but it's also hard to deal with because it is dependent on not just the light source itself, it's depending on where you're viewing from, what the ambient lighting conditions are, and also what you're doing in the space. And that's why the specification currently does not address glare. The RP1, which is the office lighting recommendation from the IES, they publish a chart here and it shows at angle from vertical, which so if you assume that you're directly under the luminaire at zero, and you start ticking up at 55, 65, 75 and 85, they say that they set limits at what the intensity of the fixture should be for good VDT use. And VDT is just Video Display Terminal, computer screens essentially. So that's - - while it's important in an office, in retail where your ceiling might be higher or you're not actually using a screen, you don't need that as a concern. So we didn't address it in the specification at this time, but it is here as something we acknowledge, knowing that for offices it is something that should be considered.
Another thing that we considered is it was more of a design consideration, it was less of an anatomy of the actual fixture itself, and that has to do with spacing criteria. All really spacing criteria is is it tells you how far apart you can lay out your luminaires for uniform layout based on mounting height. So essentially when you get a spacing criterion it could be something at like 1.1 and then so you take that 1.1 and multiply it by your mounting height. And your mounting height is the distance from the work plane, the top of the work plane to the ceiling. This graphic, which Acuity* did, one of their technical documents, had provided a great visual three dimensional representation of it, so we referenced it here. And you typically talk about spacing criteria in the zero to 180 plane and the 90 to 270 plane, and sometimes in the diagonal plane. And it's not an aspect of the luminaire; it's really more of an aspect of the design. I mean the luminaire provides the information, but it's definitely something you consider when you're doing your design.
Continuing on, so an example of a 2'x2' spacing criteria, the top image there shows a 2'x2'. In the 0 to 180 plane it's a spacing criterion of 1.26 and the 90 to 270 it's also 1.26. So the red circle shows what the horizontal distribution is if you were essentially floating in the ceiling and looking down, that's the distribution you get. It's symmetrical, both the spacing criteria values are the same, and so that's why it's a circle. And the vertical distribution is what we call a co-sign distribution and it again, it's also - - the spacing criteria of both values are affected by both your vertical and your horizontal distribution. 2'x'2's because of the nature of the way they're designed tend to have closer spacing criterions. They're not always identical, they're not always symmetrical. If this had been a parabolic, which you'll see later on, it would be a slightly different distribution. But it is because of the way the lamps are oriented, going to limit some of your spacing criteria concerns. In the example below, it's a two foot by four foot troffer. And just on the very nature that you're elongating your source, that already changes your spacing criteria a little bit. It's going to be different in one axis, at least somewhat, just because you're using a source that is four feet long compared to something that is two foot. But then also this source is using different optics, and that's why you have the red oblong, which is an asymmetrical distribution, and then the vertical is more of what we call a batwing distribution, meaning that in the center, directly below the fixture, it's actually less intensity than it is farther out. And the idea is there since illuminants is equal to intensity over distant squared, when you apply a cosign in there you're essentially getting the same light levels at the center as you are farther out, and that's why - - that's the nature of the batwing distribution. And this is a very typical type of distribution that you would see for two foot, 2'x4' troffers. We'll show some more in a second, but that's just a rough idea.
So we're also looking at some other design parameters of installation of troffers. So this picture is of a New York City office, and it's showing 1'x4' troffers. One of the reasons that, and the value Jeff provided was about 8% of florescent troffers were 1'x4's is because it requires changing your grid. We're most often used to an acoustical ceiling tile grid that is a two foot spacing, usually a 2'x4', but also in this case they're showing a 2'x2'. But because they liked the look of the 1'x4' troffers for the aesthetic in the space, and also because it actually gets them really good lighting and energy savings by the way they really optimize this design, they went with a one foot wide, essentially group of tiles. So it's a one foot wide then two rows of two foot wide, then another one foot wide, and that allows the one foot four to fit in there without having to cut tiles and other stuff. It is definitely more costly because this requires more coronation, more materials that are different. So it definitely is somewhat of an aesthetic and is one of the reasons why 1'x4's have a lower use rate.
This is an installation of 2'x2' troffers in a hotel ballroom in the D.C. Metro area. You can see that their layout almost in the exactly in the same spacing, about three tiles apart in-between both either going either left or right or up to down, and that's actually one of the beauties of the 2'x2'. People like 2'x2's because they can just lay them out in the ceiling, they don't have to know how the space is going to be used, sometimes, and they can just lay it out and there's the layout, it's done. This space, because it's a hotel ballroom, it's sometimes to be setup for meetings, it could be used for social events, there's many things, so this ballroom has multiple lighting systems, so you can see a chandelier and you can also see the down lights. And this allows them the flexibility to space the luminaires out in a same orientation and actually they can expand the wall and they've got more of it. And so, one of the reasons why people like 2'x2's, but again, 2'x2's are less used than 2'x4's, again because of the grid layout and some other issues.
Then this is a more typical 2'x4' installation in an office in California, it's probably what most people think of, it knows how far apart the troffers are in this orientation and then how close they are going left to right. So up and down they're multiple ceiling tiles apart, left to right they're only two ceiling panels roughly apart. This is because that distribution I showed earlier, you can get much more coverage area for a 2'x4' than for other luminaires.
So just a review about design considerations, the first thing to know is that spacing criterion is not a performance metric. It doesn't mean that the higher number is better. It's really more of a design metric. It helps designer understand, okay if I wanted to use this luminaire, how closely together they have to be spaced or how far apart they can be spaced to get a uniform distribution. Though very low values spacing criteria in 0.9 to 1.1 or even less than 0.9. That's going to limit your ability to use the fixture because it's going to have to tighten your design up, which means you're going to use a lot more equipment to get a more uniform lighting. You could be getting ample light, but uniformity or good coverage is what spacing criterion is directing you towards. Glare should be mitigated, and then there are many varieties to spacing criteria, and this diagram here is of a 2'x4'. And again, notice how it's like a circle, but it's really not, it's more of a slight ellipse, and that's because the spacing criteria is different in the two different axis's and notice how wide it is. And so it's not entirely the batwing, but it is definitely a wide distribution here. And we use this information, the spacing criteria in the specification development because it was informative. We know that it's not just how much light you get out, it's about trying to get a sense of where it's going. Again, space criterion you can't just tell someone a number and they know exactly what the distribution looks like, but by at least specifying the criteria, spacing criteria range, you're getting a sense of where the light is going.
We did a lot of benchmarking on 2'x2's because it was the original idea and then we expanded it. The next couple of slides will review specifically 2'x2's and the different type of troffers that they are. And this theme of troffer is applicable - - these themes of our troffers are applicable to 2'x2's, 1'x4's, and 2'x4's. The first probably, first troffer was the lensed troffer. It's got a pretty good efficiency range, and again that's just optical efficiency, how much lights getting out. And so somewhere between the 10%-to-35% of the light is not leaving the fixture. And in a 2'x2' range this can use a lot of different lamps. It could be a linear lamp or it could be a bent lamp or a compact florescent, a biax of some type. And the 1'x4', it's pretty much traditionally going to be a linear T8 or a linear T5. And there's still a staggering amount of T12 out there, so it could easily be that as well. The lens helps diffuse the lamp image and it gives a more uniform appearance at the fixture level. There is not what I would call very sophisticated optics in the lens, and so the spacing criteria tends to be somewhat similar in both axis's as shown in the polar plot below hand. It is possible to get different optics for it, but this is just a generality, it is not true for all fixtures.
Probably the next troffer was the parabolic troffer. And it's a parabolic louver troffer in that the shape of the - - if you actually were in the fixture you could actually see the parabola of the louvers. The efficiency range here is definitely less, because as you try to control more of the light, you are definitely losing, it's being absorbed by the reflectors. Internal reflections, it's bouncing off the reflectors interior, back up to the roof of the fixture and so on. So there's definitely you take a hit, and as you try to control it more you take an efficiency loss. So it could be as low as 50% and as high as 72%. Ideally what happens is you're trying to put the lamp centered over the cells. I've seen that, and not always true whether it be a U-shaped lamp in a 2'x2' or some of the biax compact fluorescents in a 2'x2'. Definitely they're not entirely centering them the best way they could. The (inaudible) cell size is just dependent on your shape and your number of lamps and a number of factors, but the 2'x2', it could be - - it could range up to 64 cells, it could be as few as four cells, it all depends. This is a no subjective, no objective data, but a subjective belief is that a majority of 2'x2's and 2'x4's and 1'x4's are parabolic. And you can see the distribution below the image. This is not entirely a batwing because it is dropping below in the center, it is higher there than it is on the periphery of the distribution, the black line showing the vertical distribution, but it is definitely a more sculpted distribution than the previous one we saw earlier. And notice how the spacing criterion is getting bigger and changing.
In the mid '90's, they have what are called basket troffers, also direct/indirect, there's various names on it, and it's definitely the intent of it is to give more of a soft appearance of it. The efficiency here is very broad, but it's definitely lower than other types of troffers. It can be as low as 33%, meaning two thirds of the light is still being absorbed inside the fixture, to as high as about 80%. And, as I said, there are recessed direct/indirect, and usually there's a cage that's either a perforated metal or some type of other material around the lamp, and that's why it's also called the basket because if you look at the upper right image you can kind of see, oh, the basket and the lamps inside there. The basket could be a side mount to the left or center mounted. It could be perforated, it could be other materials. It is definitely more of aesthetic type of troffer, and it is available in the 1'x4', the 2'x2', and the 2'x4'. The idea is it kind of gives a soft appearance. And because you're bouncing the light around, you know so the lamp is dropped in this basket and then it's being reflected off the reflector at the top of the troffer and then bounced down, as well as you have light leaving the perforated metal, you have a different distribution. It absorbs some of the light, but also that's why it's kind of very wide and very blobby, and that's why the spacing criterion is what is shown below there. It is definitely limited in more kind of places where you're trying to make an appearance or aesthetic statement, than a typical everyday troffer.
At the turn of the millennium then we have these new troffers. These are - - they've come by many different names, high-performance troffer is what some people call them; some people call them volumetric. I like the more technical jargon term of non-planar lensed. And the reason why I use that very cumbersome term is that the lamp chamber, so in this image to the upper right, the lens is curved. But not all of them are curved, some are more angular, they're just different shapes, and so that's why I use the term non-planar because it's indicative that it is not a plane, and then also that it is lensed because that's how these fixtures work. They're really a sophisticated, highly tuned optic that are designed around only a handful of lamps so they can really maximize the efficiency. That's why you're seeing efficiency in now 91% on the high range, but because of different factors and different options you can get, it can get as low as 67%. That's always going to be an issue that people are going to want options that are going to reduce some of your efficiency. The lamp is in the center of the lens, and it really needs to be a single tube, either a T5 or T8, because that's really the way the optics are designed, and you can get these in one lamp or two lamp chambers, it all depends. A small portion of installed 2'x2's is this. We're seeing more of them now, but it's still definitely, it's also more expensive compared to the previous troffers and other concerns. And so definitely it still represents a small portion of the installed 2'x2'. You're seeing kind of a distribution here that is somewhat identical, again, but this is the 2'x2'. If this was the 2'x4' it would have a slightly different distribution and spacing criteria.
At this time I'm going to return the presentation to Jeff, who's going to take us on more of what else of the specification and where we're going from here.
Thank you very much, Michael, for that informative look under the hood, so to speak, of what is the anatomy of a troffer. I hope that that helps us to understand what it is we're working with, and then hopefully for those of you that aren't in the troffer business to, as you walk through a building you can look up and say, "Hey, that's a volumetric troffer or that's a high-performance or non-planar."
Anyhow, what I'd like to do now is shift gears away from the current configurations and now look at some of the performance metrics and lead you down the path of what the specification is and how we arrived at some of the numbers.
So on this slide for the CALiPER 2'x2's, as Michael said, we've done an extensive amount of benchmarking, we started out with 2'x2', we've done 1'x4', and we got a lot of data on 2'x4', I think we'll probably gather some more. But this is just a snapshot from the CALiPER program that I talked about earlier in the presentation. You can see some of the performance levels from the standpoint of initial light output, luminaire efficacy for some of the LED products, ranging from say 40 to almost 80 lumens per watt. It's important to note that that's - - you know these tests are a couple of years old. There are some new products on the market that are easily in the 80 to in excess of 100 lumens per watt luminaire efficacy, so we've come a long ways, but nonetheless it's important to see how there's kind of been an evolution of performance and light output. We've also done some benchmarking of the florescent technology, and so the two florescent ones at the bottom, I think one of them is a T8 product, the other one is a T5, or sorry, T12 probably with 34 watt lamps.
Okay, progressing to the next slide, this is somewhat of a scatter plot, and you'll notice here that there are three different icons that we're using. One is data mining of conventional catalogued data, so conventional meaning incumbent florescent, the second is for LED products that were available, and a third are products that have been tested by the CALiPER program. The reason for this slide is to show you how some Solid-State products now are providing as much light, and in some cases more, so the horizontal axis is initial light output from the luminaire. As well as the efficacy levels are certainly competing directly, and in some cases exceeding those of the incumbent technology. So this just furthers the argument of having a performance specification and drawing a line in the sand, if you will, for higher performing products.
One of the benefits of the CALiPER program in addition to making this data available, is there is a search tool. And so what I've done for this presentation is simply gone out to the CALiPER site, did a search on troffers, and you can see here that you get a nice table back from that data mining that gives you what round it was in, what the input wattage was, minimum or initial light output, luminaire efficacy, correlated color temperature, etcetera, etcetera. I've provided this slide just so you know that the CALiPER program tracks this kind of information. You can go out and see for yourself, I'm not trying to make an argument that one particular product is really better than another, more so that we're seeing a range of performance, and frankly we haven't done a lot of CALiPER testing in the last year or two that captures some of these newer products that are on the market. But I suspect we will as things move forward.
Okay, Michael did an outstanding job of describing this concept of distribution based on the type of lensing and/or geometry and/or configuration, and so he talked about lens to parabolic, basket, and non-planar, and so I'm restating those again here. But we're also showing you some of the distributions of some of the LED products that were tested in the CALiPER program. And you can see that you really need to know what you're doing. I mean for the most part they are a cosign or kind of teardrop distribution. If you're intending to have a parabolic or a basket, you need to be aware of that as you design your layout and you design your lighting system, that you may not be getting a similar geometry with Solid-State lighting. And there's a number of reasons for that, all we're trying to do is make you aware that you need to be concerned about it if you're intending it to be conventional in nature, then you need to be aware that the LEDs may not be able to provide the exact same distribution.
Here, so two slides or three slides ago we showed you some of the CALiPER information as far as light output and efficacy; this is a similar slide but shows you the spacing criteria. Michael described to you the two different planes, 0 to 180, 90 to 270, and some of the spacing criteria associated with products. This will become important later as we talk about the actual specification itself, but we just wanted to put them here for you to kind of get a sense as to what the performance was.
Okay, let's roll up our sleeves for the next few minutes and talk about the specification. Before I go through it in greater detail, I did want you to fully understand how we approached it. So we've talked about the benchmarking that was done for 1'x4', 2'x2', and 2'x4'. Essentially, based on that benchmarking, it was decided by the alliance committee that we wanted to have or we wanted to set performance to be at least 20% greater than the average incumbent technology. So you can envision doing this data mining and finding the average, and there are all kinds of outliers and that type of thing to consider, but in general we had a pretty good sense as to what the typical luminaire was. We wanted to use spacing criteria, and as Michael said, it's not as a metric, but it's a design consideration. And what spacing criteria of course give you is equal illuminants between luminaires on the work surface, and that's why we're using it here. One of the caveats I would add is that that's just between luminaires. We don't say anything about the distribution within the beam spread or within the beam angle, but nonetheless we're striving for uniformity at the ends. We established minimum performance for linear products to 28 watt lamps with a 0.88 or 0.87 ballast factors. The reason for that is the following, and that is there is industry acceptance of reduced wattage lamps. I think all of us know that the typical T8 lamp is 32 watts, there are a number of reduced wattage products, I can do things with ballast factors to increase or decrease the light output, but we set the minimum light output benchmarking to a 28 watt lamp. And we set the spacing criteria range not so much to drive a manufacturer in a certain direction, but make sure that there's parody between technologies. If I'm a specifier and I'm doing a typical layout, I want to have products that have similar spacing criteria. I should note that service ability is a key requirement, and as we get into the specification directly you'll see that we have some issues to deal with as far as lumen maintenance and comparing lumen maintenance with incumbent technologies to Solid-State lightning technologies. And so being able to replace the light engine or driver/power supply is an important consideration.
Okay, so now let's talk about the specification itself. It does envelop 1'x4' to 2'x4' troffers. It is technology neutral, and we were careful here to say technology neutral because there are some very good high performing florescent based products that we should still be including, so we're not excluding them. And I recognize that folks think, well, if you're developing a high-performance specification, the newest technology is LED, and therefore you're focusing on LED, that's not the case. We are leaving it open-ended, but I would argue that some of the new Solid-State lighting products that are on the market really are pushing the upper boundaries. So you may naturally gravitate that way, but nonetheless we're not focusing specifically on LED or Solid-State lighting. Nominal dimensions, as you would expect, I don't need to talk about those to any length, you can see those there. Maximum height or depth is five inches, that's typical for an incumbent troffer. Michael touched on this static air handling capability, so that is a requirement. Also in the specifications, and for those of you that are fortunate to live in New York City or Chicago, you have some additional constraints placed upon you, we wanted to make sure that those were addressed in this specification as well so we weren't developing products that were excluding some of those major markets.
Okay, minimum light output, this is important to talk about, and I will go into greater detail in the next few slides, but the first thing that should strike you is that we are proposing, and I do reaffirm that this is indeed a draft specification. But we were proposing a higher initial light output for LED luminaires versus florescent, and again we'll talk about those here shortly. For 1'x4', and the reason it's less than say a 2'x4', is simply because you can have, or it's fairly typical to see a 1'x4' troffer with a singular lamp, and so that's why it's set at approximately 2,000, 2,100 lumens. 2'x2' is approximately 3,000 lumens, and 2'x4' is 4,000 lumens approximately. Keep in mind that 4,000 lumens is typically a two lamp type product. I can certainly have three and four lamp troffers, and one of the things that we are considering is perhaps setting tiers within the 2'x4' category to recognize a three lamp and four lamp minimum light outputs as well. It may not be necessary, but there may be some interest in doing that just so folks can equate one to the other.
Now we're going to roll up our sleeves a little bit, and I ask your patience here as I try and articulate this slide. And so what I've done for you, I think we're all aware that LEDs have a long gradual lumen depreciation associated with them. And so the blue and red lines represent the lumen depreciation of an LED luminaire, assuming an L70 value, and I think most of you are aware that for Solid-State lighting for LED products we set the useful life of an LED luminaire at 70% of the initial output. So the point at which 70% of the initial light output is still maintained is by definition or by the industry definition, the useful life of that luminaire. And you see products out there in the troffer category that range from 50,000 to maybe 100,000 hours, so that's why I'm showing both of these lines, both of these graphics, so that you can get a sense as to what the impact is of that long gradual lumen depreciation to 70%. Now, the green line shows you a typical T8 lamp with a 30,000 hour rated life. So if I operated that lamp and I achieved a full rated life, you'll notice that at 30,000 hours I have a lamp replacement, my light output goes back up to 100%, it ramps back down at 60,000 hours, I do another replacement at 90,000 hours, and I do a third replacement. So those lamp replacements need to be considered in your life cycle costing and your decision process. Likewise I've done a similar graphic with some of the high-performance T8 options that are out there where you can see 46,000. In fact I've seen some 32, or sorry, some 52,000 hour rated life lamps, so there are some very, very good linear replacement products on the market today. And so for that product that's the purple line. I'm looking at a lamp replacement at 50,000, or sorry, 45,000, 46,000 and 92,000 hours respectively, so I can get longer life out of that florescent product. The key thing I want you to take away from this is look at the lumen depreciation of the florescent relative to the LED. You can see at the end of life you're getting 94, maybe 95% lumen maintenance at the end of life, and with the LED products you have a substantial amount of time where the LEDs are providing less light. This is part of the reason why we are asking for higher initial light output to offset this problem. And it's a problem that we have to take up within the industry as we begin comparing florescent to LED this is going to be an issue, especially when manufacturers are claiming very, very long L70 or useful life values.
Okay, the next slide is very, very similar, same idea, but for those that are in the lighting business, you know that we don't usually run a lamp out to failure, having a serviceman go up on a ladder each time is fairly expensive, especially when I've got thousands of lamps in my facilities. So as a matter of practice, it's very common to have a group relamp conducted at 70% of rated life. So this graphic is the same thing, except that I'm now replacing the lamps at 70% of rate of life for both the 30,000 and 46,000 hour products. I guess the key thing I would take away here is that by replacing them at 70%, I have even higher maintained luminants, or lumen maintenance for these products because I'm replacing them before the end of their rated life, and therefore they're still delivering more light output, so another key consideration.
Okay, pressing on with the spec itself underneath the (inaudible) performance. For the 1'x4' and 2'x4' we have set the level at 74 luminants per watt luminaire efficacy. For 2'x2' it is 69, and I think the first question you would ask us is why not have them all the same? It goes back to our benchmarking and how we arrived at these numbers. And you can probably imagine that with 2'x2' lamps you have some of these U-bend type lamps, some of the pin based lamps, and so the fixture efficiency for those products is less than some of the linear products that are out there, and that's why there's a five point difference between the linear 1'x4' and 2'x4', and the square 2'x2'. We are specifying a spacing criteria range, and we actually invite your comments on those ranges. We're not trying to drive the market, but rather make sure that the products that come to market have similar distribution, similar spacing criteria to the products there intended to replace. So you can see that we've broken it down from the 0 to 180 plane and the 90 to 270 plane. Chromaticity or color, the nominal CCT values of 2700, 3035, 4000, and 5000 Kelvin are pretty typical for both Solid-State lighting and for florescent. For CRI, we're asking for a CRI of greater than 80. And the R9 value, and as you may be aware, CRI is a metric that is being highly scrutinized. It has certain flaws associated with it, those flaws are exasperated when it comes to Solid-State lighting, so there is a new metric on the horizon, but for the immediate future we'll continue to use it. In order to fill out the spectrum, if you will, we're setting the R9 value, which is actually outside what is used in the Ra calculation, the R average, it's actually a red swatch, a reddish swatch, and we're asking that that be greater than zero. The testing for Solid-State lighting products is, according to LM-79, which I believe you're familiar with.
Further discussing the setting the performance, at least for the linear products to 74, the Federal Energy Management Program, this is another Department of Energy Program, has already defined troffers at a 74 lumen per watt level, so that just further added confidence that the numbers that we were coming up with via our benchmarking activity had been at least vetted by the industry at some level, and then there's a precedent for setting it at those levels.
Continue on with the specification itself and looking at some of the electrical characteristics. This should be no surprise to you, most commercial buildings need a power factor of 0.90 or greater, and that equates to approximately at THD of less than 20%. Commercial building owners are actually penalized for having a poor power factor, and so for a large load they require, it's very typical to require these higher power factor ratings. We are asking for continuous dimming from full light output down to 10%, and you'll see in the next couple of slides that we have some options here, but we're asking for dimming, and we're further asking that the manufacturer provide either via their website or via a fact sheet of some type, what is compatibility with their product for various dimming controls. This is often times an issue and we want to make sure that manufacturers try their product so that once they hit the field they'll have the minimum amount of frustration with the performance on the dimming side. Driver or power supply efficiency of greater than or equal to 85%. Drivers range probably from 78 to as high as 94%. We could have remained silent, but we did want to specify some higher performing drivers. This actually directly impacts the overall luminaire efficacy because it's one of the parameters that are included in that calculation. So we didn't want to have a manufacturer selecting a poor driver and potentially poor quality driver, and yet putting in a very high performance LED module package or array, so we did want to specify a minimum there. We talked earlier about the importance, so based on the lumen maintenance curves that we saw a couple of slides ago, you can see now that having provisions for being able to replace the light emitting portion or light engine portion of our LED products is very important. And we want to make sure that that can be done readily, that it hopefully doesn't involve an electrician, but a technician can do it. But we don't want to have a proprietary situation where somebody's up there with a soldering iron trying to undo circuit boards and that type of thing. So accessibility is a requirement in the specification.
Lumen maintenance versus rated life, so we talked about this in great detail on those prior charts, we're asking for a minimum rated life for a florescent product of 30,000 hours based on a 12 hour operating cycle using programmed rapid start ballast. For LED's, and I won't go into great detail here because it's fodder for another day, but suffice to say that we're asking for 50,000 hour L70 value, we recognize that there are new protocol, there is a new protocol called type TM-21 that may ultimately be incorporated into some of these voluntary standards. But we, at this point, are relying on a L70 value of 50,000 hours, and we are evaluating it using LM-80 and what's called an in-situ temperature measurement test. And that's where you install the luminaire in its respective UL 1598 environment, allow it to achieve steady state temperature, we measure the hottest LED, we measure the power supply, and based on that information you can make projections of lumen maintenance and driver reliability, and/or life.
These are options. These aren't direct requirements; these are options that the alliance members would like to have. Emergency lighting, as you may know is for egress requirements in the instance of an emergency or an event, so two different battery pack options to provide illuminants and over a sustained period of time. There are further dimming options. So we've had this minimal dimming of 100% down to 10%, zero to 10 volts is an option, step dimming is an option. Two other continuous dimming, one down to 20% and one down to 5%, and then some of the open protocols for dimming, whether it be DALI or RDM or some other wireless technology. You know those are our options as well. Daylight sensing, if we can do some daylight harvesting and it easily integrates with the luminaires, we're all for that. You might even have some lumen maintenance controls. Maybe you under drive the luminaire initially, and as depreciation becomes more pronounced maybe you begin to drive it a little harder so that you maintain your luminance levels for a greater period of time. Load shedding or demand response, there are utilities now that can provide signals to shed load, and having that capability is desirable, especially for some of these large facilities. And the members were also interested in other technologies, and we are aware of some that are using centralized power conversion and controls because these LED's are inherently a DC low voltage type application. They lend themselves for this kind of a centralized approach, and so there are some manufacturers that offer these types of power supplies and conversions as well.
Okay, let's talk about retrofit options, so today we've talked about the specification, and arguably that is for new construction. We didn't want this webinar to not at least raise the issue of retrofitting existing troffers. With that you'll note that I'm going to be very careful and not say anything about LED replacement lamps. The reason being is that those are - - they are a complicated installation, you need to know a lot about your space, you need to exercise due diligence, and rather than saying that you should do it, I'm going to default and say that these are the typical retrofit options that we see in the industry today. And where in certain cases you can certainly consider Solid-State lighting or LED linear replacement lamps, but do it with open eyes and with due diligence. So if you're space is over lighted by 30% using standard T8 lamps and instant start ballast, your easiest way to obtain energy savings is by using reduced wattage lamps. So most T8s are 32 watt, but they make reduced wattage versions in 30, 28, and 25 watts. So if you're over lit you can certainly next time you relamp you can use lower wattage lamps.
If your space is over lit by 30% and you're using T12 lamps and magnetic ballasts, and to coin a phrase from one of our colleagues, for goodness sake, change them right this minute to T8 high-performance, or what we call super T8 type products. You get extended light output, but you mate them with a low ballast factor ballast, so you're essentially under driving them at the ballast, but the lamps are higher output, and plus you can get very long life, and this is the 46 to 52,000 hours I was talking about earlier.
Now, if your space is over lit by 30% now and you have high electric rates, and very high relamping costs, and greater than 5,000 hours of operation per year, we're recommending you do a life cycle cost analysis. And this is where you can begin to consider LED lamps. They are very expensive. You can justify them perhaps, but with all you've learned in this presentation about spacing criteria and distributions, you need to be very careful that if you start just doing a one-for-one replacement you can actually void the lighting design by not providing the similar distribution in your fixtures. Your fixtures are designed for omnidirectional light sources, these linear replacement lamps are directional, and so we're saying that you should consider them, but do due diligence. If that means buying a few and doing mock ups, great.
Okay, nearing the end of the presentation. We wanted to provide you some information resources. This has been brought to you today by the Commercial Building Energy Alliance; you can see its link here. The specification that is, again, still draft and we are inviting comments on, can be found at the same location underneath technologies, so you can go and download the specification itself. DOE's main Solid-State lighting program is just ssl.energy.gov.
We're also putting the DesignLights Consortium link here. And the DesignLights Consortium, and I'll go to the next slide, and this is actually a screen shot of the DesignLights Consortium website, is a consortium of utilities and market transformation groups across the country that have set specifications and maintain approved products for those specifications. They currently have 19 different categories. They do include 2'x4', sorry, 1'x4', 2'x2', and 2'x4' troffers. The performance levels currently are slightly less than what is being proposed by the alliance members, but nonetheless this is a site that you can go to and not only see what the performance levels are, but you can also do searches for higher performing products.
Okay, so what are the next steps? As I said, now the specification is still draft, this is an open invitation for you to comment. We ask that those comments be received by November 18th, that's a Friday, so close of business on November 18th. You can email your comments to cbea.pnnl.gov, that's the incoming email for that. We anticipate a final specification completed by January 1st. We are openly trying to do demonstration projects, we're doing a couple now with the GSA for 2'x2' troffers, but as time goes forward I think we'd be interested in 2'x4' and 1'x4' application as well. And also moving forward we will be using this spec not only encouraging in the federal sector, but also some of the voluntary programs that you see, the DesignLights being an example.
And this concludes the presentation today. I'm providing my contact information and Michael's contact information, and at this time we will end the presentation and then move off into the question-and-answer period and we'll take as many of your questions as we possibly can.
Great. Jeff and Michael, thanks so much for a very informative presentation. So Jeff, I'll turn it over to you to handle the Q&A now.
Thank you, Linda. On the slide now, or excuse me, on the screen now we've actually posted a link for this and previous webinars, so if you're interested in this presentation and prior ones done by the alliance, you can actually go to this link here. As Linda mentioned, in the upper right-hand corner there's a two white or three white pages that you can actually download the presentation right now, so I encourage you to do that if you're interested.
So folks, we have about 15 minutes of time to go over as many questions as we possibly can. As you can imagine with this number of attendees there are quite a high number of questions, so what I'm going to do is I'm going to take a couple of questions, I'll ask my colleague Michael to take a couple of questions and we will do our best to get through as many as we can. And then we'll certainly encourage any comments that you would choose to make after the fact as well.
So let me take a couple of them here and then I will give a couple to Mr. Michael.
One of the questions and this actually goes back to early on in the presentation: Is the market share of alliance members on the slide 7 equal to the share of floor area space?
And I believe the answer there is yes, that's how we broke them down.
Second question was: Do we include pendant suspended luminaires for office lighting in the spec?
The answer is no. We were specifically looking at recessed troffers. Certainly one could argue that you could suspend a troffer and perhaps use an element of this presentation of the specification, but our focus really was on ceiling mounted troffers, which is of course the great majority of products that are out there.
A third question that has come up and this is kind of an open-ended question in asking about: What's the comparison of using electronic ballast relative to the older T12 technology magnetic ballasts?
I think this question stems from the fact that early on in the electronic era, if you will; there were concerns of premature failures of electronic ballasts. I, for the most part, believe that that's been long since solved. Yes, magnetic ballast offer some durability, but nonetheless the modern electronic ballast, as far as I know, is certainly a 20 year proposition or certainly of that era.
Michael, why don't you go ahead and take the question on edge-lighting and uniformity output from edge-light LED fixtures or troffers.
Sure, thanks, Jeff. The question here is: Can you comment on the differences, pros and cons, between edge-lit and direct-lit (inaudible) troffers?
Well, I mean there's definitely a mixture of both pros and cons. Just so people understand what edge-lit means, essentially it would be where if you imagine that the LED's were parallel to the ground and they were lighting into some type of optical film, wave guide, you getting into really crazy optics at this point, and it would shoot across the face of the troffer. And then based on whatever the optical system is it would actually shape the beam and hopefully redistribute the light. GE actually has a really neat edge-lit pendant they showed at LIGHTFAIR. One of the neat features of it was when it was turned off it was clear. Why I bring this up is that that may not be why you'd want an edge-lighted troffer because when it's off you can do different things with it, but one of the neat things is is that it becomes a clear surface. And if you're just looking into the box of a troffer, while it might have a deconstructionist artistic point of view, it may not be what everyone wants. There's definitely an advantage of putting them behind the actual optical material and direct light it from just an ease of optics and probably a cost of optics and tooling and other stuff like that, and that's why we see a lot more of direct lighted troffers than edge-lighted troffers for the variety of reasons there. I think I highlighted some of the pros and cons there.
I just wanted to touch base on a couple other comments before I return it to Jeff. One of the comments was this question here: On the anatomy of a troffer slide, why was the efficacy and optical efficiency of the three lamp troffer higher than the two lamp T8?
This is really just kind of the problem with averages. So if you'll see that in the third column it's the number certified - - surveyed, so 35 two lamp troffers were surveyed, and in the case of the three lamp, four three lamp troffers were surveyed. So the problem there is that just any differences it caused the average to skew one way or the other in the four lamp proposition versus the 35. The other limitation here was we have actually broken the data out into many different systems, but in this case we're actually amalgamating it here and we're combining it all the different optical systems at the same time. So I can't really tell you without going through my notes what the breakdown of the different optical systems are and why the efficacies are the way they are. Just the thing I would tell you is that as you pack more lamps into a smaller surface, your efficacy is probably going to be reduced, but there's probably something more going on in the 35 two lamp troffers that is causing that.
The two other questions I'm going to quickly address and then I'll give it back to Jeff is: One question here was low depth troffers could be more efficient than detailed troffers? I'm sorry, low depth louvers.
The term efficient, yes, if we mean optically efficient as in a low depth louver is not absorbing as much light and is allowing more light out so it's more optically efficient, I would probably agree with that, but they also could be more glary that way. So it really is what do you really want to accomplish? Do you want more light output or do you want to shape the light of where you want it to go, do you want to limit for glare? There are a lot of things to think about. Getting light out is not always the end result, lighting the space effectively is usually the end result, which actually entries into the next question.
Since the CBEA specifications are intended to help non-lighting professionals, the person was concerned the difficulty in establishing quality thresholds in the specification, and they want to know why more lighting quality metrics were not addressed?
And really we tried to touch that earlier. Yes, lumens per watt is not the only metric we're looking at, we do try to look at spacing criterion to help with distribution. It is really hard to include metrics on glare, one because glare is very user dependent. If it's in a nine foot ceiling versus a 15 foot ceiling, that's going to change your glare perception. Whether or not it's a black painted ceiling versus a white ceiling, that's going to change your glare perception. So it's really hard to develop a specification that is going to work for all applications when you get into lighting quality. The RP1 does have the VDT requirements on intensity, but they're also setting their parameters much better than we are because we're looking at all troffers in general. Lighting quality is always a concern of mine and it should be a concern of everyone's, but it was really hard to write a large cross-cutting specification to address the lighting quality if you don't know all the give parameters. Something to keep in mind when you're doing a design or considering a product, but it's hard to right from the get-go. I'll return to Jeff for a little bit.
Thank you, Michael. Heading down the list of questions, one of the questions was: The initial efficacy of LED to florescent is interesting, but what about maintained lumens?
And I hope that we went over that in sufficient detail, that we're a little concerned about focusing just on initial light output versus maintained. And I think I'll just say it for those that are probably not as familiar. When we go about designing a system, it's fairly common practice in the industry to design what are called mean lumens, which is typically 40% of the lamps rated life. You know that's the level that you try and maintain as far as the minimum for your design over time. So we do have somewhat of a conundrum. We have a florescent technology now that maintains a very high percentage of its initial light output. We have an LED technology that has a long steady gradual decay, and you can envision a long operating hours where a LED system is delivering less light than its florescent counterpart. So as I stated in that one particular slide, what we're trying to do is to set a higher initial light output for Solid-State lighting to at least minimize that disparity. But nonetheless, if you're specifying these products, the Solid-State lighting products, you do need to be aware of that when you go about designing so that you make sure that you maintain the minimum acceptable level for your application.
One of the questions was: The efficacies that we showed for florescent 2'x4' were in the 40's, and as far as lumens per watt, what fixtures were these non-planar 2'x4's run about 80 lumens per watt.
I guess the first thing I would mention is that the numbers that we've shown you hear today are luminaire efficacies, so it has net output divided by input power. So that's the net light output from your luminaire divided by the input power. And you're right, that on some of these florescent systems, and we certainly didn't try to go out and find the best, we wanted to do some benchmarking so they are - - some of them are 34 watt magnetically ballasted 2'x4' troffers. I know we do have one in there that is a typical T8 product. So point noted that we certainly didn't show you the best florescent offerings today, and yes, there are some 2'x4's that are florescent based that are approaching 70 to 80 lumens per watt luminaire efficacy.
I had a comment as far as: Glad to see that we're considering technology neutral.
That made sense to us, thank you.
Which lamp, which 28 watt lamp is used for minimum performance, T5 or T8?
The benchmarking that we did was for T8, so that's a reduced wattage T8 florescent that was used in the benchmarking.
Why does the spec revolve around initial light output rather than mean light?
Okay, so I think I already explained that we are trying to get at that by requiring at least a slightly higher initial light output for the LED systems to compensate for that.
Michael, do you have a couple that you can queue up while I flip slides?
Yes I do, I just want to, I appreciate the comment that just came in of, "One person's glare is another person's sparkle." It's very appropriate, so whoever wrote that, thank you. Related to some other comments here, or questions here, one was: Does the 20% above average use a different average for each distribution or does it consider each of four different (inaudible) distributions create the four baseline average? Basically, how did we come up with the 20%? Is it looking at a separate one for each distribution or is it aggregating it?
It is more of an aggregate value.
The person does ask if that raises a concern if the average is based on all troffers aren't we skewed toward flat lens or higher glare products.
I would say no because we did not do a weighted average based on our understanding of shipments in the market or installed troffers, we did really more of just a review and an average of the available products out there. And definitely while - - so definitely there's a lot more louver, a parabolic louver options probably than anything else. I mean when you start thinking about all the different variations in louvers you can have, those tend to permeate most of the list.
Other questions: So people have been asking about the coronation between specifications and utilities using the program.
This specification is very similar, and I believe surpasses the DesignLight, as Jeff said. So there are definitely utility programs who are looking at it. There are definitely a number of comments about NEMA premium ballast. Yeah, if you look at some of the work that's been going on in the industry in the last couple of years, florescent ballasts are really highly efficient, both through industry activities like NEMA as well as (Inaudible) efforts through a required ballast efficiency. So you've seen really ballast are pretty much pushing the edge of efficiency they can get to.
Someone asked about relative costs between florescent and LED troffers. This person said they're seeing costs of LED at two to three times florescent.
I would say, sure, I've seen prices like that. I've also seen florescent products at two to three times that as well. So for instance, you can get I think a pretty generic flat lens troffer or a louver troffer for about 60 to 80 bucks depending on where you look, and then you can get something more high-end like the non-planar lens or a direct/indirect. I've seen those push the boundaries of $200 to $300, so there's definitely a huge range of florescent products out there in price. Troffer prices, I've seen them as high, for LED troffers, I've seen them as high as $700 and there are new products coming out that are probably right now in the neighborhood of $250 or lower. So prices vary, it really depends on your options and your relationship with manufacturers. And I've been given the cane being pulled off the stage, and I'm told that at this point we are out of questions and I'm told to thank you. Pay attention to the distribution for more webinars and other information.
Great. Well, thank you Michael and Jeff for a very informative presentation. And I want to thank all of you for participating today. Again, you've got the emails for Michael and Jeff as well as an email for the Commercial Building Energy Alliances and the draft specification is posted so please visit the CBEA website to pick that up. With that I would like to close, and again, thanks to all of you for participating, you may now disconnect.