LEDs have exceeded the lumens-per-watt (luminous-efficacy) of typical incandescent bulbs by about double.  Announcements of late 2008 show efficacy measurements exceed fluorescent technology. 

The LED manufacturer rates lumen output at a specific junction temperature, typically 25°C, and the component integrator often uses that lumen figure to promote the new widget.  Few LEDs perform in the real world as they did in laboratory tests.  LED marketing has become clever and caused the lighting industry to think in terms like "wall plug efficiency."    (Note that Energy Star calls this "Luminaire Efficacy")

Here we discuss a few hopeful ideas or rumors, and some of the reality to support or dispel them. 
   Let's get started.
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The popularity of LED Lighting brings a lot of wannabe   experts    to the scene.  Even with poorly designed products lacking quality control in production, LED products may survive the warranty period and never give the R.O.I. you paid for. 

Your LED product should be built to at least   ISO 9001:2008 certification.
Is the manufacturer listed as an Energy Star Partner?

Begin with a Google or Yahoo Search.  
Type in the company name or product (within quotes if more than one word) followed with keywords,
  e.g. failure, fault, recall, etc.        Try these:
                Yahoo    Google     DogPile     MSN    ASK    (click refresh to get latest)

Next search financial records and duration in business, then see if their state of filing records are up to date.  Today, it's a red flag if LED Lighting companies haven't shown reasonable growth (at least 25%) within the first two years. 

There are several sites on the Internet that make this research an instant reality.
        Manta is a free business record service, you register to use.
        Hoovers a free trial D&B Business Search Service
        Free Public Records Finder
        Experian Business Reports for a fee

Next, check their status in the State where they filed for incorporation.  You can search for any state with SOS (Secretary of State) Business Entity Search. 
      Here are a few links for example.
When you find the company, hope to see "Active" rather than "Default" or especially "Revoked" or even "Permanently Revoked".      

As a consultant, I've seen amazing Engineering and Production shortcuts tried, and failed.  One fantastic claim made by a manufacturer in AR was that they practiced Lean Six Sigma procedures,  however, they suffered a 20% failure rate right off the production line.  Their builds didn't match their BOMs, and that was explained by non-existent assembly documentation.  Their bad units were put aside; they shipped the 80% that did work without knowing why 20% didn't.    What do you think happened with those they shipped?

Mike Bruck Intencity Lighting, teams with Steve Weintz SBW Ventures, to address and recover from product failures and problems.

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Entrepreneurs may need to re-write a few laws of thermodynamics when showing screw-in LED light bulb replacements.  These inventions need more thought to live up to claims.

Will the consumer settle for less light because it's a novel gadget?  Reducing their lighting requirements will itself save energy, but is that what they intended?  This leaves the market open for a rude awakening - buyer beware?

LEDs produce more light per watt than an incandescent bulb.  But most of the watts they consume is still converted to heat, and if not dissipated, will drastically shorten their life.  Heat doesn't radiate from an LED, so it must be conducted away, usually into an exchanger to free flowing air.  The LED junction must operate below about 85°C.  Here's an example of proper LED thermal design for a bulb replacement. 

A light bulb is fundamentally a heater that just happens to send out a little visible light.  Yes, a heater, and the socket it's screwed into is designed to protect the base and wiring from all that heat.  In other words, the socket is a very poor thermal path for cooling that screw-in LED light bulb.  Something must cool the LED, and cooling will not happen through the socket.

Estimate heat exchange to get those lumens and keep T_J below 85°C:
Each watt of LED power needs about 6 square inches of surface area in free air for cooling.  (See Lumileds apps. guide Luxeon Thermal Design Guide  pdf file.)
That 3" post-it-note on your desk is 9 square inches.  Roll it up, fold it & shape it to get an idea of the size neded to dissipate about 1.5 watts. 

If the LED has twice the efficacy of incandescent, then lumen for lumen, a 60-watt light bulb replacement must dissipate 30-watts of heat.  That's about 180 square inches of surface metal attached to that screw-in LED device.

To get the lumens and keep the life, you gotta cool that thing.  Of course an alternative is forced air with a fan.
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That seems like a practical statement since the LED traffic signal switch-over measured over 80 percent energy savings.  But beware.

LED traffic signals saved energy because the signals are monochromatic (single color), and LEDs naturally emit only a single color so there's no extra light generated to throw away.  The extra color spectrum from incandescent bulbs was absorbed in a filter (colored lens) and simply unnecessary. 

The issue of saving energy with LEDs comes down to producing only what the task requires, AND using all the light that is produced.  Competing technologies may produce higher lumens, but it's not easy getting all that light where it's needed, and usually any extra light is just masked.

A typical bulb type luminaire may be only 60% effective, or in other words, a lot of the light it produces doesn't go to the intended target (it becomes light pollution or is merely masked off).  And, the higher efficacy HID bulbs require a ballast to start the arc and regulate the gas ionization.  The ballast may consume 20% of the electrical energy going into the luminaire.

   That's  0.6×0.8 = 0.48
       or Metal Halide = 80 lumens/watt ×0.48 = 38   delivered lumens per watt.

In contrast, the LED luminaire may be 90% effective with a power supply that's 90% efficient. 
   That's  0.9×0.9 = 0.81
          or LEDs = 65 lumens/watt ×0.81 = 53   delivered lumens per watt.
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: ef·fi·ca·cy Pronunciation: 'e-fi-k&-sE Function:  noun  Inflected Form(s):  plural -cies  : the power to produce an effect

Some readers are puzzled over the use of this word efficacy verses efficiency.  "Efficiency" cannot relate a measure of input energy to a unit of light output.  Some readers may not be aware that "light" refers only to the visible portion of the spectrum, and not to other emissions from an emitter.  Efficacy is the appropriate term for comparing a light effect from an electrical input, and is commonly used by lighting specialists and LED Engineers worldwide.  Efficiency would be used for example, to compare power in to power out of a power supply, or, compare the light produced by a bulb inside a fixture to the light emitted from that fixture, etc.

LEDs are now able to compete with Fluorescent, maybe a little better.  However, review the math shown above. 

The HID bulb industry has created an illusion that high lumens are required for certain tasks, because they get little better than half those lumens out of the fixture.  Where have all those lumens been going, and at what cost to the consumer?  Is this deceptive?  You bet it is.    See this breakdown on Sodium Lighting effectiveness.

LED chip manufacturers are boasting of about 100 lumens per watt (at 25°C  T_J  of course). 

Now the barrier to keep an eye on for the illumination business is not these few percent of inefficiency, it's the LED's high cost per lumen.  HID bulbs can jump in increments of ten thousand lumens for mere dollars, whereas LEDs cannot.
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On the surface that statement is sort of true.  We don't get a monthly bill for using the Sun's energy, and the process of converting the Sun to electricity produces no harmful side effects.  However, lighting is needed at night when the Sun is not around, so our night lighting is powered by energy stored in batteries during the day.  Batteries contain materials that aren't land-fill friendly, and they must be replaced every few years, so costs are quite high.  Photo-voltaic cells are the key to harnessing the Sun's rays, and those cells are not cheap.  The solar panels may cost 2 or 3 times that of the light they power, and the amortization may be 10 or more years.

Bottom line may not be clear, but it is clear that accuracy of a catch phrase like that and so many others depends entirely on the application.  Solar powered nighttime lighting can be justified only when there is no electrical service, or, when complete independence from the utility company is essential.  Solar power won't likely float when the competing power source is hydroelectric.
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Several LED luminaire suppliers are trying to use a Scotopic advantage when promoting less lumens to do an equivalent lighting job.  There will be lots more to come on this subject, so check back for updates.  In the meantime, here is a LRLL White Paper that shines some light on the Scotopic issue. 

I've heard one sales pitch for indoor lighting, promoting LEDs to replace Metal Halide and Fluorescent for factory assembly work with the claim that less lumens are acceptable due to that "Scotopic Advantage."   This couldn't be more misleading.  As you can clearly see, any type of visual work requires direct focus which relies upon the cones, which allows no Scotopic advantage whatsoever.  Even worse, detailed assembly work can have parts and pieces of wide color range for which the LED is known to be deficient in the red region.  There will be objects that appear an abnormal color under LED lighting.

Another case of buyer beware, and a potential black eye for LED sales people. 
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Technology has come into the equation, and with that comes many ways to measure performance and even ROI.  Electronic controls are now involved that can inform the owner of pending failure or lumen depreciation, they can allow remote control of your luminaire.  Can you imagine a communications protocol between streetlights and your central office?  It's here.  Now you need interchangeability, and NEMA can drive manufacturer functional compatibility.

Computer generated Photometric files are here too.  NEMA can draft appropriate performance Standards, and possibly find ways to police deceptive practices.  We used to expect the Photometric file came from an independent lab, but until there are NEMA Type numbers for Luminaires, you should insist on Certified Independent IES Files and Test Lab Report before committing poles and luminaires.

    We can hope that NEMA will raise Manufacturer Standards and Ethics.     Leave your comments here.
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Bogus claims like this will make skeptics from the optimists. 

The IESNA (Illuminating Engineering Society of North America) "Standards" provide uniform measurement criteria for comparing lighting fixtures.  They have many lighting categories and types.  They have a category and type number for nearly every type, style and technology of lighting fixture, but the IESNA is not an endorsement of a lighting fixture.

The IESNA Standard defines a Photometric file format for a candela plot of luminaire output.  This along with layout software that will run on most computers, can determine the quantity, and plot the location and spacing for luminaires to provide a lighting criteria, levels and uniformity based on your selection.  For this, a Photometric file (a tabular format of typically 180° x 360° angular luminance measurement) is required for the particular luminaire.  For this layout software, your Manufacturer must have an IES file available for the luminaire, and it should be a file of actual measurements from a certifed independent lab.
  
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LEDs have a reputation for long life, but they are also easily abused.  Light Emitting Diodes are more fragile than some designers are aware, but electrical or thermal deficiencies in their fixture design will not often cause a sudden failure.  Too much current or too much heat, for example, could result in a 50,000 hour part lasting only 10,000 hours. 

High quality, high output monochromatic LEDs can provide 70% of their original lumen output at 100,000 hours IF they are not abused.  Note that Monochromatic is stipulated because the Phosphor in PC (Phosphor Converted) white LEDs can degrade faster than the LED junction.  This can be caused from thermal overload, excessive ultra-violet exposure, moisture, or a number of things.  Most manufacturers have overcome these problems, now the integrator must adhere to good science.

As an example, I have tested this Journée Lotus product, and found the heat sink section to exceed 65°C with a room ambient of only 24°C.  A rise this high will surely limit the LED life to far less than the manufacturer's claim of 40,000 hours.  The phosphor output shifts through several colors while the assembly is stabilizing, which is a good sign the phosphor is not very happy.  But as an office or desk lamp, if you don't leave it on all night, how many years is 10,000 hours, really?  So you need to be careful not to burn yourself, because it will leave a welt.     Time will tell.
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Correlated Color Temperature Chart

Color Rendering Index  (CRI) indicates how well a test source renders eight standard colors of intermediate saturation, when compared to a reference lamp of the same color temperature.  Lab measured CRI is a comparison against a spectrally continuous red-weighted reference.  Field conducted CRI tests are subjective with Human observers when luminance levels are below 3 cd/m2. 

The industry is discovering that CRI is not the best metric for comparing LED light sources, especially at Mesopic levels.  Originally developed in 1964, this index is based on outdated color models and assumes illumination sources with broad spectral distributions, whereas LEDs are narrow-band sources.  And, nighttime lighting requirements fall primarily in the Mesopic range where our color sensitivity shifts with luminance, and there is no defined index.  Several standards bodies are addressing this deficiency, and in the interim, Color Temperature may be the most suitable tool for comparison because it is independent of observer subjectivity.  Click for more...

Correlated Color temperature (CCT) defines a color as the temperature in degrees Kelvin that a "black body" source must reach in order to produce that same color.  CCT describes the dominant color without regard to Human visual response or the source technology and is more appropriate for comparison of visual effectiveness at lower light levels and among different technologies. 

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Which measurement shall I use:  Candela or Lumens?

The user community, contractors, agencies and municipalities, have established lighting criteria so they can maintain a quality of illuminance through time.  Specifying a lighting fixture by lumens is merely requiring a power consumption and not a lighting criteria.  The size of an area illuminated to a specific value does define a minimum amount of delivered lumens, but lightmeters measure footcandles or lux, not lumens. 

Now we have LEED certification to ensure Green.

Properly managed LEDs in a suitable luminaire have been field-measured as placing 3-times more foot-candles on the ground per watt than other technologies, partly because they can be directed where most suitable, and partly because they produce light only where needed. 

Be careful of the Lumen Legacy.  Select fixtures based on application footcandles or lux rather than lumens.
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