You pasted in the shortened display text of the link, not the full link itself.
Oops, not sure how it got copied like that. This is the working link where I got the quote that people surveyed generally preferred the fluorescent lighting technology
http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/caliper_21-2_t8.pdf
There is definitely a niche for LEDs to replace CFLs, even if linear fluorescents are more efficient and give better color quality for the moment.
Not every situation allows troffers.
LEDs do have applications, but they're not quite the same as transistors are to vacuum tubes.
]exactly what iwire said. As far as performance, lets see, you get rid of a ballastand get rid of a mercury filled device and a light that is usually rated between 40-50K hours, I don't get how the LED's lack in performance.
Absolutely wrong. LEDs and fluorescent utilize a very similar power supply which is an added point of failure that equally disadvantage both technologies. It's actually becoming more similar. Higher voltage LEDs are getting utilized and a string of LEDs operate at about the same level as fluorescent lamps.
There are inferior quality sytems that do not use an external inductor or capacitors solely to reduce production cost. They're a leakage that is slipping past the current loop hole in SSL standards which is still in its infancy and do not address flicker measures. It's like going back to magnetic ballst, but worse, because phosphors used in solid state fluorescent LEDs have a short persistence and emphasizes the effect of 100 or 120 Hz flicker. "mercury" is a cheap jab used by LED advocates. Semiconductor factories are rather environmentally dirty.
Also, you get a green cast with fluorescents unless you get lamps that have been color corrected with magenta which can give off a purple hue. And true, you get some green cast with LED's but you just need to find ones that have a high CRI and tunable color.
All low pressure mercury discharge fluorescent lamps produce a few distinctive mercury lines which causes a green cast on photographic films due to the differences in sensitivities from human eyes to film emulsion. Most solid state semiconductor fluorescent lamps (LEDs) have a distinctive spike around 450 nm in deep blue region.
Human eyes, CCDs, CMOS' and film all sees in color but the characteristics in the way it responds to spectrum is different. A light source that's rich in output in spectrum where our eyes have dull senses don't affect the color rendition much. If the sensor device is more sensitive to this spectrum than our eyes, it will affect how it's captured a lot.
You bring up an important subject. LED industry rates their life at L70, a prediction of when 30% of lumen otuput is lost. Chromaticity is measured using MacAdams Ellipses delta 'uv. Modern fluorescent lamp technology only loses less than 10% output in lifetime and 50,000 + hour rated fluorescent lamps are readily available.
There is another parameter for LEDs called L90, which is the point of 10% lumen loss. I think this needs to be PROMINENTLY and display both the new value and L90 value as fluorescent lamps do. The crap fluorescent lamps that lose 30% of output are not in common use. That's the technology of the obsolete 110W cool white HO lamps.
LEDs are susceptible to color shift with use. It is likely to be the factor that condemn decorative light emission products even if the lumen output is within specs. This type of failure is NOT covered by warranty on LEDs by conveniently defining a type of degradation that renders them unfit for use, but still lighting up.
They've done some field observations on this very troubling concern about LEDs.
http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/2013_gateway_color-maintenance.pdf
Don't see how you can wrong with that. It took me a while to find ones that impressed me but I have found them.[/B]
I think they use GaAs type like red LEDs, which contains the highly metal arsenic. It also adds complexity to controls and possibility of light quality degradation like infusion of PWM modulation flicker. This isn't an LED exclusive domain. Fluorescent luminaries could use equally complex control gears to mix output from multiple lamps the same way it is done with LEDs to produce tunable color output.