I'm starting to see a lot of LEDs in airport retail spaces--especially downlights and track heads. There are still a lot of fluorescents being used too, of course, although as LEDs get better they eat up more and more of that market. I haven't seen it myself, but I've heard that at least one terminal at LAX has replaced much of its concealed fluorescent soffit lighting with LED strips.
A few years ago it was hard to find a listed LED luminaire, and when my boss asked the manufacturers at the lighting trade show in Vegas they told him, "it's low voltage; it doesn't need to be listed." Over the next couple of years they learned differently, as various Building Departments wouldn't allow the use of their products because they weren't listed. Now there's a pretty wide selection of listed LEDs from reputable manufacturers.
One issue we still run into fairly often is the listing of remote power supplies, although this is more of an issue of inconsistency between different inspectors. When the power supply is not an integral part of the luminaire, some inspectors insist that the luminaire and power supply must be listed together as a complete lighting system. Other inspectors say that's not necessary, as long as the power supply and luminaire are both listed. Still other inspectors will accept a listed luminaire with a UL Recognized power supply (probably because they don't know the difference between Listed and Recognized). There are other variations out there too, like the inspector who doesn't care if the luminaire is listed as long as the power supply is. In this regard, the problem is with the Building Department not educating its inspectors and having a uniform policy outlining what's acceptable and what isn't.
Regarding the technology itself, LEDs have gotten much better in terms of brightness. Color uniformity is pretty good as well, if you stick with a reputable brand and buy all your fixtures from the same lot. A 3500K LED from Tech Lighting and a 3500K LED from Lithonia may well put out noticeably different colors of light. Similarly, a 3500K Tech Lighting LED manufactured in June may give you light that is noticeably a different color than that same model of LED manufactured in August. But, as I understand it, the same issue exists with fluorescent lamps (although perhaps not as pronounced).
I think there is a lot of "Look at us! We're green!" going on, especially when lighting designers play power factor games with their power supplies (since the Energy Code is based around Watts rather than Volt-Amps, it becomes preferable to use a 60 watt power supply with 60% power factor instead of a 75 watt power supply with 90% power factor, even though the 60 watt draws more amps). But that doesn't mean that LEDs aren't a good alternative in many cases. Personally, I don't think LEDs have quite "arrived" yet, but they're very close.
As for price, a good LED fixture is still more expensive than a comparable fluorescent fixture, but not by such a huge margin as it would have been a couple of years ago. If you're looking for cheap, it's hard to beat a fluorescent strip light or a drop-in fluorescent 2x4. But if the customer wants a certain "look," LEDs can be a good option.
(Disclaimer: I am not affiliated with any manufacturer/vendor of LEDs or any other lighting product.
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