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LED Lighting Tips
   
   
Solid State Lighting (SSL) and Light Emitting Diodes (LED)
  
Informational Sites for SSL:
    
    Home page: www.ssl.energy.gov
    
    R&D Portfolio: www.ssl.energy.gov/projects.html
  
    SSL Quality Advocates: www.ssl.energy.gov/advocates.html
  
    ENERGY STAR for SSL: www.ssl.energy.gov/energy_star.html
 
    CALiPER: www.ssl.energy.gov/caliper.html
  
    Standards Development: www.ssl.energy.gov/standards.html
 
    GATEWAY Demonstrations: www.ssl.energy.gov/gatewaydemos.html
  
    Design Competitions: www.ssl.energy.gov/competitions.html
 
    Technical Information Network for SSL: www.ssl.energy.gov/technetwork.html
  
    Using LEDs: www.ssl.energy.gov/using_leds.html

    Labeling LED Products: www.lightingfacts.com
  
   
LED Energy Savings and Payback
Payback or Return on Investment (ROI) derived from LED lighting with white light emitting diodes is delivered at several different levels.
  
LED lighting provides immediate savings in power consumption. As usage increases, further reaching benefits build and accelerate payback in the savings associated with bulb replacement, infrastructure and safety. When LED installation moves from individual sites to local or regional deployment we will see payback factors that include environmental considerations.
 
   
Facility Level Payback
    Bulb inventory: LED eliminates the dollars tied up in inventorying many types of expensive replacement fluorescent,       halogen, and incandescent bulbs.
 
    Labor: LED greatly reduces the labor associated with maintaining the lighting infrastructure.
 
    Recycling: Fluorescent bulbs contain 10 to 40mg of mercury each. LED eliminates the direct cost and labor cost       associated with recycling. This translates to removing pounds of mercury from the recycling stream for just an average       sized building.
 
    Infrastructure savings: The low voltage (12V) wiring used by SSL is considerably easier to install than 120VAC, saving       installation dollars on materials, reducing labor associated with installation, AND reducing dollars spent to ensure safety       of the 120VAC system.
 
   
Regional Deployment Payback
   
    Potential reduction of $125 billion spending on electricity over the period 2005-2025.
  
    Potential 50% reduction in electricity use for lighting in the United States.
   
    Potential 30% reduction in total electricity production a savings of 3.5 quadrillion BTUs in the United States alone.
   
    Potential elimination of 28-40 million metric tons of carbon emission annually.
   
    Reduction in America’s dependence on foreign energy sources and the incalculable savings associated with that!
   
  
Manufacturers Offering LED Products
    Bulbrite
      www.bulbrite.com
      A leading manufacturer and reliable supplier of quality LED replacement bulbs.
 
    CREE LED Lighting
      www.creells.com
      view video
      Setting the standard for all ceiling installed LED fixtures! 4",5"and 6" LED downlights - 12w, dimmable, true white light at       27K and 30K. 48w and 58w LED 2x2 lay-ins for regular and high ceilings.
 
    ELCO Lighting Company
      www.elcolighting.com
      Offering LED Step-lights for indoor and outdoor applications and LED Rope Lighting.
   
    Framburg
      www.framburg.com
      Offering indoor and outdoor LED accent and cove lighting.
      
    House of Troy
      www.houseoftroy.com
      Renowned for unsurpassed quality in LED picture, piano, and desk lamps.
  
    Kichler Lighting Group
      www.kichler.com
      Recognized as the most desirable LED manufacturer of outdoor landscape lighting: LED deck lights, LED path lights as       well as indoor/outdoor LED step-lights & LED floodlights. Most notable for their award winning LED puck and LED       undercabinet lighting products.
  
    Tech Lighting
      www.techlighting.com
      Presenting state-of-the-art 12v LED pendants and LED trackheads.
   
   
When Specifying LEDS - What you really need to know!
  * LUMENS
   - LEDS are specified in Lumens
   - Lumens are based on high-speed production test equipment at "ideal" conditions
   - LEDS should NOT be evaluated simply on "wattage" or lumens per watt
   - Use as a baseline reference +/- 10%

 * COLOR
   - What is white?
   - Specifying # of bins is insufficient
   - Specifying CCT is insufficient
   - Understand bin ranges and expectation
   - What happens to the color over time?

 * LIFETIME
   - LEDs historically have been measured to a lifetime of 50% output
   - L70 one of the KEY lifetime parameters
   - Temperature totally affects the LED lifetime
   - Lifetime consideration should also include electronics and materials, not just the LEDs

 * OPTICAL SOLUTIONS
   - Optical elements are mounted directly onto the LED to shape a desired beam pattern

 * THERMAL SOLUTIONS
   - Heat MUST be transferred away from the LED by a heat sink

 * ELECTRONIC SOLUTIONS
   - LED drivers improve color and brightness performance
 
  
The Difference between Scotopic and Photopic Vision
When rating the effectiveness of LEDs, the difference between Scotopic and Photopic vision is an important factor to account for. LEDs demonstrate increased luminance with respect to Scotopic vision, providing a cleaner, brighter light and better vision in regards to the human eye.

The light sensitive membrane in the human eye (the retina) contains millions of receptors that covert light into information that is sent to the brain. The two categories of receptors are called cones and rods. The central part of the retina contains only cones. The rest of the retina contains both cones and rods, with rods being dominant in population.

Until now, the accepted belief has been that cones (photopic) deal with day vision and rods (scoptopic) deal with night vision. As a result of this belief, lighting manufacturers have developed lights which focus on the cone’s sensitivity and have not addressed the rod’s sensitivity. In reality, both cones and rods work in conjunction with each other depending on the lighting conditions. LED light is received and translated by BOTH photoreceptors (cones and rods) in the human eye, providing better viewing conditions.
 
 
About Lighting Facts - Accuracy in LED Product Information
For the solid-state lighting (SSL) market to grow, consumers must have confidence that the product they are buying is well designed and performs to their expectations. Sponsored by the U.S. Department of Energy (DOE), SSL Quality Advocates is a voluntary pledge program to assure that LED lighting is represented accurately as it reaches the market. SSL Quality Advocates pledge to use the Lighting Facts™ label to document the performance of products they manufacture, sell, distribute, or promote, based on industry-standard testing.

Similar to a nutrition label, the Lighting Facts Label provides a quick summary of product performance data. Luminaire manufacturers who take the SSL Quality Advocates pledge agree to use the label to disclose performance results in five areas — lumens, efficacy, watts, correlated color temperature (CCT) and color rendering index (CRI) — as measured by the new industry standard for testing photometric performance, IES LM-79-2008.

Additional metrics related to reliability, product consistency, construction, and other parameters may be considered in future editions of the label. By introducing transparency to the lighting supply chain, the Lighting Facts label will guard against exaggerated claims and help ensure a satisfactory experience for lighting buyers.
view PDF file
  
   
Architectural SSL MAGAZINE
February 2009 Issue – Reprinted
12 Questions Your LED Luminaire Supplier MUST Answer
 
1) Which LED supplier did you choose and why? Is it a reliable company that you have heard of? What references can be     provided?
 
2) Has your LED supplier provided an IESNA LM-80 test report? Any good LED supplier will be able to supply this report     beginning in mid-2009; if not, why not? Be particularly careful about 5mm LEDs and the cheaper SMD LED lamps. These     LED products are often marketed as having 50,000 hours of rated life, but may not be able to deliver it under all the     temperature and environment conditions.
 
3) What is the operating temperature range specification and what is the maximum junction temperature (Tj) of the LED     lamps over that operating range? This is a straight-forward calculation based on the maximum temperature inside the     fixture and drive current that your fixture manufacturer has selected for the LED lamps. Your fixture manufacturer should     be very familiar with this concept and readily able to provide this information. Some LED products are not capable of     being operated in high ambient temperature conditions without violating maximum LED junction temperatures (Tj). In     colder climates some drive electronics may not function properly. It is important to look at both temperature extremes to     make certain that fixture is suitable for your application.
   
4) What is the expected L70 lifetime of your fixture? How did you calculate it? If the answer to this question is anything like     "My LED Company told me so", you should look into the matter more closely. In the longer term (beyond mid-2009) any     fixture L70 lifetime should be listed on the IESNA LM-80 test report for the LEDs used, and also the worst case expected     internal ambient temperature the LEDs will see, as well as the maximum junction temperature (Tj) of the LEDs. These     latter two points are critical and MUST be provided by the fixture manufacturer. The LM-80 report alone from the LED     supplier is almost meaningless without these other two data points. Over the short term - until the LED manufacturers     have time to comply with LM-80-you may have to rely on vendor data, but don't let that stop you from asking the     question!

5) Can you supply an IESNDA LM-79 test report from an independent 3rd party laboratory for your fixture and an .ies data     file? This is a critical data point. The LM-79 report will give you the assurance that the photometrics reported in the     marketing literature (lumens, spatial distribution, CCT, CRI, etc.) have been verified by a third party. The LM-79 report     also gives total fixture efficacy (lumens per watt), Power Factor and a data file in an .ies format. Without this assurance,     the marketing literature is subject to question.

6) What are the delivered lumens and LPW of the fixture? Unfortunately it is a common marketing practice that some fixture     manufacturers take the number of lumens on the LED data sheet in optimal test conditions (say 100lm) and multiply the     answer times the number of LEDs in the system (say, 10) and report that they have a 1,000 lumen luminaire system.     This is not only misleading, it is physically impossible. LEDs lose lumens through thermal stabilization and optical losses,     and all LED driver types have conversion losses. Make your fixture manufacturer do the homework and report the data in     terms of delivered lumens for the application and LPW in terms of wall plug efficiency.

7) Is the chromaticity of the fixture in the ANSI C78.377A color space and is it stable over time? How you do know? This is     especially important for indoor luminaries. If it is not in the ANSI color space, then the color of the luminaire could be     pinkish or greenish in hue. Color point stability is a common problem in lower quality LED fixtures. It can be a result of     poor LED selection, poor thermal management, or both. Make your fixture supplier convince you that the LEDs selected     are right for the application (Lighting-class LEDs; not 5mm lamps designed for toys and novelties for example), and that     the fixture design has a good thermal management capacity for the worst-case expected operating environment (an     insulated ceiling, for example).

8) Does the color of the light output vary from fixture to fixture or in different spatial locations for a single fixture? This is     another common problem with lower quality LED fixtures. This problem can be solved through various technical means     (binning - color mixing of LEDs, control systems) in the luminaire system design, but again, your fixture manufacturer     has to do the homework to prevent you from having this headache later.

9) What is the Power Factor of your fixture? How much power does it consume in the "off" state?Power Factor should be at     least 0.7 for residential applications, 0.9 for commercial (U.S. DOE Energy Star criteria). This is easily achieved with a     fairly standard driver design, but is often ignored on lower quality luminaire products. Poorly designed LED systems can     consume almost as much power in the "off" state as they do in the "on" state. The DOE Energy Star requirement is for no     more than 0.5 watts. Make your fixture supplier check this information to save you heartache and energy later!

10) Have you applied for the DOE Energy Star for this fixture? Why/why not? DOE has a very well thought-out set of criteria     required to get an Energy Star rating. It does not yet apply to all lighting fixture types, but the Energy Star criteria are a     rigorous way to assure the quality of a fixture and it could be instructive to know if a manufacturer has applied for this or     not.

11) Is your fixture lead-free, mercury-free and RoHS (Restriction Of Hazardous Substances) compliant? This is a key     question regarding sustainability. Lead-free and RoHS compliance - all the way through to the packaging the luminaire     arrives in - are easily achievable with modern manufacturing technology. Insist on this!!!!!!!!

12) What is your warranty and do you have the means to stand behind it? A reasonable warranty should be about one third     of the expected L70 lifetime (e.g. for an expected 50,000 hour L70, a 15,000 hour warranty is reasonable) and the     company giving the warranty should be of reasonable size and solid financial means. The Energy Star program requires     a 3 year warranty for example (the Energy Star warranty is starting to become the "standard" in warranties).