The Kirlin Company is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to C.E.S. Records for AIA members. Certificates of Completion for non-AIA members are available on request.
This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
In a CFL , an electric current is driven through a tube containing gases. This reaction produces ultraviolet light that gets transformed into visible light by the fluorescent coating (called phosphor) on the inside of the tube. A CFL releases about 80% of its energy as heat
LED lighting products use semiconductors to produce light very efficiently. By passing current through the diode, excess energy is either released as a photon of light or heat. The heat must be thermally managed, but no infrared is emitted into the space. Heat produced is minimal in comparison to other sources.
Generally 5 watts or less and used in either “stand-alone”
systems or fixtures using multiple LED’s. Single die work
best with optics for varying beam spreads.
Generally 3 watts or greater and containing 4 or more die.
As with all LED, thermal management is critical and can be
challenging with multi-die packages.
Self Boarded multi-die LED, usually over 5 watts. These
LED typically do not lend themselves to the use of optics,
but are generators of many lumens. Thermal
management is mission critical with these packages.
Creation of Light Anatomy of a Die P layer P/N Junction N layer Substrate P Electrode (Anode) N Electrode (Cathode) “ Active Layer” “ Depletion Layer” “ Forbidden Layer” Junction
Creation of Light Anatomy of a Die P/N Junction Substrate (Anode) (Cathode) Current + + + + + + + + + + + + + + + Current Out - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bond Wire Applying current causes electrons to flow, the union creates a release of energy - either light or heat
Spectral Power Distribution Comparison Typical White Power LED (blue diode w/phosphors) Spike at 450 nm represents the contribution from the blue diode. Wavelengths of light above 500 nm are result of the phosphors.
Blue photons of light excite and mix with the phosphor
to create white light
Phosphor most commonly placed directly over diode
or “conformally coated” on diode
High CRI available (unique phosphor blends)
Purchase “zones” or bins of chromaticity
Lighting Class White Binning Similar LEDs can vary in…
Forward Voltage (efficiency)
Color (customized phosphor blend)
Removing most of the variables, allows more precise binning.
Results of Premium binning procedures Due to variance during production, a bin is a “zone” of chromaticity in which a customer will receive product. in variance Red bin represents a 57% reduction
Standards for LED product testing L70 “ End of Life” determined at 70% of initial lumen output. Junction Temperature, Operating Temperature, Drive Current all play a role in the determination of L70
Standards for LED product testing L70 predicated on keeping the LEDs cool.
Approved Method for the Electrical and Photometric Testing of Solid-State Lighting Devices “Specifies a standard test method for measuring the photometric properties of SSL devices, allowing calculation of luminaire efficacy.”
This is the actual photometry of a LED Luminaire. It is always
best to have truly independent testing done – especially with
Ambient temperature has effects
“ Cold” Lumens or testing at start-up is inaccurate and not
realistic as lumens will decrease as luminaire warms
Standards for LED product testing ___________________________________________________
Lumen output can be dramatically reduced due to a rise in junction temperature
IES LM-80-2008 Approved Method for Measuring Lumen Depreciation of LED Light Sources “ Specifies a standard method for measuring the lumen depreciation of LEDs, allowing calculation of LED lifetime.” This is the actual, real-life (lab) lumen/life testing of diodes (but not in a luminaire). 6,000 hours are required, however 10,000 hours are preferred. This equates to 8 months of operational testing! Prior to LM80, most reputable LED manufacturers used the Assist method of calculation, proven to be very reliable. Standards for LED product testing ___________________________________________________
Conjunction with Lighting Control Technology (motion sensors, timed on/off, daylight sense dimming)
Color changing (building exterior)
21 st century power (Solar)
The 12 questions your LED Luminaire Supplier must answer Mark McClear of Cree Scott Riesebosch of CRS Electronics February, 2009
The 12 questions… 1) Is your Diode Supplier a reliable company?
The 12 questions… 2) Has your diode supplier provided an IESNA LM-80 Test? LM-80 was finalized and published by the IESNA in September of 2008. All reputable LED manufacturers should now be submitting existing and new LED packages for LM-80 testing. If your fixture manufacturer cannot produce LM-80 test results for the LED they are employing in their luminaire – buyer beware!
The 12 questions… 3) What is the operating range specification and what is the maximum junction temperature (Tj) of the lamps over that percentage range? Each LED has operating characteristics that need to be adhered to when employing them in a lighting fixture. The most critical item of note is the LED package operating junction temperature or Tj. The Luminaire manufacturer should be able to provide not only maximum rated junction temperature for the LED, but also what the Tj is as operated in their fixture. Care should be taken when applying luminaires in different climates (operating temperatures). Quality Luminaire manufacturers will build in an allowance in their design for variances in ambient operating temperatures.
The 12 questions… 4) What is the expected L-70 lifetime of your fixture ? How was it calculated? L70 is a designation for the amount of time it will take a LED to depreciate to 70% initial lumen output (as set forth by LM-79 photometric testing) in a fixture. Again, what is the fixture’s L70 and at what ambient is that tested at? Is it a realistic ambient?
The 12 questions… 5) Can you supply an IESNA LM-79 test report and is it from a third party laboratory with an .ies file? Independent Testing Laboratories, Boulder Colorado is one of the premier testing houses for lighting fixtures.
The 12 questions… 6) What are the delivered lumens and LPW of the fixture? The delivered lumens stated in fixture manufacturer’s literature should reflect the “total” lumens each fixture produces. When evaluating the specification sheet, the stated luminous output is the same as the output reported to us in our LM-79 test, in other words, “no in-house tricks.” We do not report “ lighthead” lumens, but actual light delivered out of the fixture. Fixture wattage should be total draw, including driver losses.
The 12 questions… 7) Is the chromaticity of the fixture in the ANSI C78.377A color space and is it stable over time? How do you know? Reputable LED manufacturers all publish binning practices. Typical bins are representative of (7) MacAdams Ellipse. Lighting Class LEDs should be much more precise (3) Ellipse.
The 12 questions… MacAdams Ellipse Over 90 percent of the population can see the difference in (7) Ellipse A reduction from 7 to 3 MacAdams Ellipse reduces the percentage to less than 65 percent.
The 12 questions… 8) Does the color of the light output vary from fixture to fixture or in different spatial locations for a single fixture? Fixture manufacturers need to be very careful and record keep the bins from which they receive their LED and supply to project sites. How critical this is depends on the quantity of LEDs used in the fixture design, as well as the size of the bins in which they purchase from.
The 12 questions… 9) What is the power factor of your fixture? How much power does it consume in the off position? Properly designed luminaires should consume no power in the off position. Power factor is how effectively the electrical design (driver) uses the input power it receives. Luminaires should meet or exceed the USDOE Energy Star rating.
The 12 questions… 10) Have you applied for DOE Energy Star for this fixture? Why/Why not? Energy Star has traditionally been associated with residential grade products. Although it is better to have than have not, many new luminaires have either not been submitted or await the review of the DOE. Similar to appliances, Energy Star sets a minimum performance level and is not the end all to quality LED luminaires.
The 12 questions… 11) Is your fixture lead free, mercury free, and RoHS compliant? In order to meet the Reduction of Hazardous Substances compliance, lead and mercury are eliminated from the product, as well as an extensive list of other potentially harmful materials.
The 12 questions… 12) What is the warranty and do you have the means to STAND BEHIND IT? LED Lighting represents an unprecedented level of reliability and the manufacturer should have the confidence to stand behind their design. Warranties should be a minimum of 3 year, as long as 5 year and incorporate not only the LED circuitry, but driver and optics as well. Does the manufacturer you are dealing with have experience in the lighting industry? Have they stood behind prior technologies? Will they be around in the future to service an offered warranty?
Typical Designs should include serviceable parts