Top five questions to ask when specifying LEDs

These are the top five questions every lighting designer and engineer needs to ask before specifying LEDs.

10/01/2014


Learning objectives

  • Name the important factors to consider when selecting LED lighting for a facility.
  • Understand how to mitigate costs by evaluating specific factors.
  • Identify how controls can help further maximize cost savings.

Figure 1: More than 700 Acculamp ALSMR16 LED lamps from Acuity Brands are installed throughout the Wilshire high-rise condos in Los Angeles to improve building efficiencies. Courtesy: Acuity BrandsToday’s challenge for lighting engineers is to deliver solutions on time and on budget, but to also achieve maximum energy savings. It is ironic that lighting, once an energy hog, is now a solution engineers are asked to specify to help reduce energy usage. Consider what U.S. Energy Secretary Steven Chu once said: “The cleanest energy is not solar, geothermal, or wind. It is the energy saved; the energy that is never used at all.”

 According to the U.S. Dept. of Energy, widespread use of LED lighting has the greatest potential impact on energy savings in the United States. Luckily, the highly efficient nature of LED luminaires, coupled with their innate ability to be controlled, makes this digitally addressable light source ideal for many uses. With increased demand for LED lighting, specifying engineers must know the details of selecting and specifying LED lighting. 

Specifying energy-efficient lighting used to be a challenge for engineers, but with the opportunity LEDs present to the lighting industry today, the task no longer needs to be difficult. While the general perception of LED lighting is it is costly, there are ways to mitigate costs with well-written specifications by making educated choices.

1. Does the value outweigh the cost?

Short answer: Yes. 

An LED lighting solution, when properly applied, can achieve better illumination for everyday living by delivering superior performance and significant energy savings. However, the perception of better illumination is that it comes at a high cost. While some LEDs are more costly, there is typically a reason. Long lifetimes, high color rendering index (CRI), tight binning, extreme ambients, lots of control, and serviceability are often the reasons for elevated prices. 

The important point about these features is that engineers can choose what types of opportunities LED lighting provides. Since LEDs typically cost more than luminaires with traditional sources, customers often expect a longer life, better color quality, better distribution, reduced energy usage, and more control.

Figure 2: Constructed in French Renaissance Revival style in the late 19th century, the Castle Museum in Saginaw, Mich., installed Lithonia Lighting D-Series LED floodlights from Acuity Brands to enhance the look and energy savings of the building’s outdoor lighting. Courtesy: Acuity Brands2. What is a reasonable lifetime?

The lifetime of LED luminaires matters greatly to end users because LEDs offer unprecedented levels of energy efficiency and have an exceptional lifetime. But what exactly is considered a reasonable lifetime, given that published lifetimes are frequently exaggerated?

Lifetimes are often inflated because LEDs are assembled in fixtures and are subject to many adverse conditions. These conditions include but are not limited to a wide range of ambient temperatures, drive current variations (i.e. inrush, surge, dimming), being turned on and off several times a day, thermal shock, and a variety of vibrations.

With that said, quality LED products can last 25 times longer than incandescent products and use 75% less energy. A quality lifetime for LED lighting is based on the application. For example, for applications where lighting is on for 24 hours a day, seven days a week, it is likely that 50,000 to 60,000 hours would be a reasonable lifetime. 

3. How important is a high CRI? 

CRI is a measure of a light source's ability to show object colors. But when specifying LED luminaires, just how important is specifying a high CRI? Not all applications have a high CRI for existing lighting, and even if applications do have a high CRI that does not mean it is needed when replacing lighting with LEDs. 

A lower CRI often means a higher lumen per watt (Lm/W). It all comes down to considering price requirements. A higher Lm/W provides a lower cost. The lower cost is affiliated with fewer LEDs, less energy used, and better total cost of ownership. While a decent price for LEDs with a high CRI is not unheard of, lower CRI readings typically provide a better cost for projects. 

Engineers should specify only what they need and not what used to exist for the CRI. Additionally, high Lm/W does not guarantee quality illumination. 

Figure 3: A general contractor, DPR Construction, installed Acuity Brands LED lighting in its California office saving the company with decreased energy and maintenance costs. Courtesy: Acuity Brands4. What does the project really need?

When specifying a new project, a number of factors must be considered to align the lighting solution with the project’s needs. For example, when considering ways to mitigate prices of LED lighting, consider how important energy savings is versus a high Lm/W. While both options are available and can exist in one fixture, the end user may not need both. 

Also, prioritize the need for extreme ambients. Projects seldom need extreme ambients unless the temperatures are dramatically hot or cold. Having extreme ambients could provide additional costs for specialized components as higher ratings require more thermal control. 

Because each application is different, make sure each application is specified individually instead of just measuring to equivalent projects. There is typically more than one option for Lm/W to meet required specs, so consider the options and select the one that is best for the application.

5. Does more control mean more money?

Initially, the use of controls with LED luminaires does mean an additional cost. However, simple controls can pay for themselves very quickly and, throughout time, produce a dramatic return on investment. The initial increase in energy savings provides a quick financial return on investing in LED luminaires with controls. Then, over time, those same controls allow LED luminaires to have even longer life, which saves money that would have been spent replacing traditional luminaires. 

LEDs are critical, as are controls. Pairing LED lighting with controls allows luminaires to perform at their highest ability. Dimming LED luminaires does not damage them, and turning the luminaire on and off does not affect their life. Therefore, LED lighting integrated with controls is a simple solution to save additional energy and to create a convenient user experience. 

From the cost to the opportunity to pair LED lighting with controls, there are a wide range of choices for engineers to consider when specifying lighting. The right solution for the application can deliver energy and maintenance savings, and enhance the quality of light.

Mark Hand is vice president of engineering - indoor for Acuity Brands Lighting. He has been entrenched for 9 years in the lighting industry in the research, conceptualization, development, and commercialization of LED luminaires.



, , 10/16/14 02:09 PM:

A slight variation and a little rebuttal to Mark Hand, vice president of engineering - indoor for Acuity Brands Lighting. He has been entrenched for 9 years in the lighting industry in the research, conceptualization, development, and commercialization of LED luminaires.
By Tim Gravert
Entrenched for more years in all that stuff, but in another type of LED we call ActiveLED
1. Does the value outweigh the cost?
Short answer: Yes. I agree, but want to point out that the word, ”Value”, has many levels to consider when it comes to solid-state.
An LED lighting solution, when properly applied, can achieve better illumination for everyday living by delivering superior performance and significant energy savings. However, the perception of better illumination is that it comes at a high cost. While some LEDs are more costly, there is typically a reason. Long lifetimes, high color rendering index (CRI), tight binning, extreme ambients, lots of control, and serviceability are often the reasons for elevated prices.
I think this assumption is made based upon how bigger makers have always done things in the past. Man made light has always been a consumable based business model and is where, “planned obsolesces” actually comes from.
REF: http://www.youtube.com/watch?v=vfbbF3oxf-E
After you watch this well-known documentary, worth a re-watch, since i think we need to consider the company making the LEDs point of view before we take their assumptions as the last word. Their is a bias that has created a consumable version of the LED that better fits how things have been vs. how great they could be. Our ActiveLEDs have been designed to do what the others have decided not to make. What is possible is so much more.
The important point about these features is that engineers can choose what types of opportunities LED lighting provides. Since LEDs typically cost more than luminaires with traditional sources, customers often expect a longer life, better color quality, better distribution, reduced energy usage, and more control.
I believe this is where the rubber hits the road, Expectations. What we are always expecting is never what we get from the lighting industry as it is currently defined. We are going to get into the "lifetime" as the next step, but let me plant a seed here that the promised a light loss warranty of any 50,000hours or more has strings I think the bigger companies making most of these systems in china, all have attached to their warranty and lifetime claims. If you look at the fine print you will see that these long ratings come from test conducted in very easy to survive environments that are not connected to the "Ambients" as Mark refers. We are living within a reality the test are not testing for.


2. What is a reasonable lifetime?
The lifetime of LED luminaires matters greatly to end users because LEDs offer unprecedented levels of energy efficiency and have an exceptional lifetime. But what exactly is considered a reasonable lifetime, given that published lifetimes are frequently exaggerated?
Frequently is an understatement. I think, we can say with confidence that the lighting companies and the best IESNA defined testing methods, all over estimate lifetime. Just look a the CFL curly cue blubs we have been forced feed and you will see 7 to 10 years right on the package. Have any of you ever had one of those making that grade? Now look at the new LEDs and this gets exaggerated even more. Why do we let this continue to be the standard? One might say we are very well trained consumers?

Have any of you ever heard about the 5 monkeys training program? Well look it up, because we all have fallen victim to this concept and most of us have never known. Email me at tim@g2led.com and I will send you a fun diagram explaining it.


Lifetimes are often inflated because LEDs are assembled in fixtures and are subject to many adverse conditions. These conditions include but are not limited to a wide range of ambient temperatures, drive current variations (i.e. inrush, surge, dimming), being turned on and off several times a day, thermal shock, and a variety of vibrations.
On this point we can agree, but this is also where we find the compromise.
Quality LED products can last 25 times longer than incandescent products and use 75% less energy. A quality lifetime for LED lighting is based on the application. For example, for applications where lighting is on for 24 hours a day, seven days a week, it is likely that 50,000 to 60,000 hours would be a reasonable lifetime.

Understanding the laws of physics will unlock this potential, Mark, our the author, is talking about. What he does not not seem to understand though is that by the way our mainstream has applied the means of testing, the mainstream is making all of these assumption impossible. The others including us are rendered blind by the test methods we are all forcefully asked to look at things through.
Why Our product is better is because we know better. we know better to look deeper than anyone else is looking into what kills the LED. If you want the expectation you have been given about the LED, you need to do things in a very specific way. These ways are so specific we have patents upon our process and method all the way from the driver to the way the fixtures are designed and runThe best example of this is that we are 2 to 3 times cooler than all other LED light makers in the world at the Tj or Junction temp in the UL-1598 testing. As far as mainstream test go this is the best one as it looks exactly where it counts.









3. How important is a high CRI?

It’s important, but before we over think this, we need to point out that this test all along has had a major flaw that bring its own accuracy into question. It is supposed to have been fixed, but i don't agree. This problem was resolved by the NIST, and this resolution was even endorsed by Dr. James Brodrick, lighting program manager for the U.S. Department of Energy. Have any of you ever heard about the CQS test from the NIST? A quote from the NIST,” The CRI has a number of problems, particularly when applied to LEDs or when used as an indicator of color quality. The uniform color space used to calculate color difference is outdated and no longer recommended for use.” If anyone is interested in seeing these documents, please contact me directly at tgravert@ringdale.com and I will send them your way and you can draw your own conclusions.
CRI is a measure of a light source's ability to show object colors. But when specifying LED luminaires, just how important is specifying a high CRI? Not all applications have a high CRI for existing lighting, and even if applications do have a high CRI that does not mean it is needed when replacing lighting with LEDs.
A lower CRI often means a higher lumen per watt (Lm/W). It all comes down to considering price requirements. A higher Lm/W provides a lower cost. The lower cost is affiliated with fewer LEDs, less energy used, and better total cost of ownership. While a decent price for LEDs with a high CRI is not unheard of, lower CRI readings typically provide a better cost for projects.
Engineers should specify only what they need and not what used to exist for the CRI. Additionally, high Lm/W does not guarantee quality illumination.
The argument here from our perspective, is going to go deeper in order to get to those raised expectations again. I think, the industry out of necessity has us all on the chase for more and more lumens per watt to get the LED they want and need to sustain their business model in the market’s main demand. They want high lumen organic consumable LEDs that fit back into the old incandescent timelines. This is why I argue the main reason they need this is because the traditional lighting engineers have always had light loss factored Lights. If you are selling the same problem which is that you start out bright on day one, with a ticking loss right out of the gate, you need to have the same characteristics in all of your test method no matter what technology you are selling. In this article's case, i think Mark is giving the engineer leeway, and I think we can argue this is necessary because I believe we all should be using the CQS test developed by the NIST instead of the CRI. The CRI is a broken but well accepted flaw in testing standards. Being acceptable makes it the norm, but if you want good color rendering you need to look deeper than most experts are looking.
Again, we come back to the five monkeys. If you pin the experts down as to why they bucked a good idea, they will say, it is because that’s what we have always done it before. In my opinion, that is never a good reason.
4. What does the project really need?
When specifying a new project, a number of factors must be considered to align the lighting solution with the project’s needs. For example, when considering ways to mitigate prices of LED lighting, consider how important energy savings is versus a high Lm/W. While both options are available and can exist in one fixture, the end user may not need both.
Also, prioritize the need for extreme ambients. Projects seldom need extreme ambients unless the temperatures are dramatically hot or cold. Having extreme ambients could provide additional costs for specialized components as higher ratings require more thermal control.

Ambients? Did Mark just make up a new word? The reference here is heat and the heat he has been refereeing to is the ambient air temps you and I are planning on running your new LEDs in. To ask this question implies that they have not planned for reality. As absurd as that may sound, that is the truth. Most engineers specifying LED lights when asked don’t understand how easy the LED testing really is. The warmest air we are even allowed to test in for mainstream certifications and listings like, DLC, is 25c or 77f. This gets worse though, because most of the long lifetime ratings the others post on their packages are based upon tests ran in air 5c or 41f. Do they think we are all planning on running their engineered LEDs in a refrigerator or freezer?
I know that we are the only LED manufacturer in the world that has planned for you to run our systems in whatever air you could find. The cold side -60c and on the hot side to +60c or 140f environments. We have literally planned for a worst case situation that you can’t possible encounter right before the world ends. That allows our customers and the engineers specifying our ActiveLED lights to avoid the next suggestion.

Because each application is different, make sure each application is specified individually instead of just measuring to equivalent projects. There is typically more than one option for Lm/W to meet required specs, so consider the options and select the one that is best for the application.

I believe the conclusion here is if you need to ask about “ambient” than you need to reconsider who is making the LEDs your engineer has decided to specify for you. You are going to get an LED that will fail and well before their published lifetime rating unless you take this serious.





5. Does more control mean more money?
Initially, the use of controls with LED luminaires does mean an additional cost. However, simple controls can pay for themselves very quickly and, throughout time, produce a dramatic return on investment. The initial increase in energy savings provides a quick financial return on investing in LED luminaires with controls. Then, over time, those same controls allow LED luminaires to have even longer life, which saves money that would have been spent replacing traditional luminaires.
LEDs are critical, as are controls. Pairing LED lighting with controls allows luminaires to perform at their highest ability. Dimming LED luminaires does not damage them, and turning the luminaire on and off does not affect their life. Therefore, LED lighting integrated with controls is a simple solution to save additional energy and to create a convenient user experience.
From the cost to the opportunity to pair LED lighting with controls, there are a wide range of choices for engineers to consider when specifying lighting. The right solution for the application can deliver energy and maintenance savings, and enhance the quality of light.

On this point I can only agree. Controls need to be simple and self sustaining or their cost always outweigh their sold benefits. I see that the bigger companies are creating control methods that render the entire point of being maintenance free and any energy saving you find moot. They become moot because these complex control methods come with their own maintenance issues and new maintenance contracts. Don’t believe me; just ask yourself why you are paying for an IT guy to be on your staff. It’s because digital control protocols require daily attention, or they get way out of control.

This rebuttal was provided to you by your humble G2 and ActiveLED expert.
TWillyG2 on Twitter or tim @g2led.com
Tim Gravert 970-690-7568
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
Combined heat and power; Assessing replacement of electrical systems; Energy codes and lighting; Salary Survey; Fan efficiency
Commissioning lighting control systems; 2016 Commissioning Giants; Design high-efficiency hot water systems for hospitals; Evaluating condensation and condensate
Solving HVAC challenges; Thermal comfort criteria; Liquid-immersion cooling; Specifying VRF systems; 2016 Product of the Year winners
Driving motor efficiency; Preventing Arc Flash in mission critical facilities; Integrating alternative power and existing electrical systems
Putting COPS into context; Designing medium-voltage electrical systems; Planning and designing resilient, efficient data centers; The nine steps of designing generator fuel systems
Designing generator systems; Using online commissioning tools; Selective coordination best practices
As brand protection manager for Eaton’s Electrical Sector, Tom Grace oversees counterfeit awareness...
Amara Rozgus is chief editor and content manager of Consulting-Specifier Engineer magazine.
IEEE power industry experts bring their combined experience in the electrical power industry...
Michael Heinsdorf, P.E., LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec.
click me