SIGH… I’ve never encountered the “wall plug efficiency” rating, but in the future, I will attempt to divine it through specifications that I’m provided with. I think you know what I mean.
Ugh.
What you are really asking about is “fixture” efficiency.
The lumen rating is measure with a bare bulb in an spherical integrator. This means that you can take a highly efficient lamp and stick it into a decorative fixture and get very little useful light out of it. Or, you can take a mediocre lamp and put it into a polished parabolic reflector and get a lot of light just where you want it.
I don’t think consumers care very much, and so the manufacturers simply rate the amount of “raw” light coming off of the lamp.
Actually, consumers (and I) do care. We also care about other reasonable, understandable comparisons!
Industrial fixtures tout their efficiency. I’ve never seen a consumer fixture that did.
I’d believe the last advantage listed overrides the other three added together.
Except in extreme cases, the cost to purchase and install lighting is going to be negligible compared to the cost of the electricity to run them over their lifespan. It’d be a very short-sighted company indeed that didn’t consider those particular Benjamins.
This happens to be a question that I have been following closely over the years.
Today’s best fluorescent tubes (not CFLs), T5 HE (High Efficiency) tubes with electronic ballast, have reached 100 Lumens per Watt.
PDF link showing representative T5 specs
The older, thicker T8 tubes would achieve 75 - 90 Lumens per Watt, also using top quality electronic ballasts.
PDF link showing typical T8 specs
Today I was browsing LED bulbs in the store and the best ones had over 100 Lumens per Watt. Also Ra at least 90, 360 degree light cone and I think very good power factor.
I think the best LED bulbs have now reached a performance equal to the best fluorescent tubes.
I recently bought some strange looking LED bulbs for my wall sconces. They use 60 watt, candelabra base, “flame” shaped bulbs. Instead of discreet LEDs, they have several luminous strips that glow all over their whole surface. Each strip is actually a continuous band wrapped around a contact at each end, like a rubber band pulled tight. They are very impressive in use.
The 60 watt replacements use 4.5 watts and produce 500 lumens, or 111 lumens per watt. I replaced one to start and they matched or outperformed the old incandescent bulbs.
Dennis
You’re right there’s a difference between what you can casually purchase in a brick-and-mortar retail store for residential use vs what’s commercially available vs what is available in the lab.
The Cree XP-E is used in many flashlights and industrial lighting, and it does 141 lumens per watt: http://www.cree.com/led-components/products/xlamp-leds-discrete/xlamp-xp-e-high-efficiency-white
There are commercial high-bay LED fixtures which exceed 200 lumens per watt: The 8 Most Efficient LED High Bay Fixtures
The Samsung LM301B is available right now and it does 220 lumens per watt: Samsung Achieves 220 Lumens per Watt with New Mid-Power LED Package - LEDinside
Cree Semiconductor reached 300 lumens per watt in 2014. This was a prototype but production units are closing in on this: http://www.cree.com/news-media/news/article/cree-first-to-break-300-lumens-per-watt-barrier
As already described, despite this efficiency LEDs still get quite hot. On many high-power metal-body LED flashlights, there are warnings stenciled about the heat.
Unlike incandescent bulbs that radiate heat in their beam, LEDs project a “cold beam”. So the heat must generally be carried away (initially) by conduction not radiation. This can make retrofit in existing fixtures difficult, even if the LED is producing less overall heat.
That is why some LED retrofit bulbs like the bi-pin MR16 are heavily fluted or have a tiny cooling fan inside them – there is no good heat path to conduct the LED heat through the two tiny electrical supply pins.
Thanks, joema, that’s great info! The 100 lm/W “barrier” seems to have been very tough to break, for the common types of retail products sold to normal people. Can’t wait to buy high-quality 200-300 lm/W bulbs and fixtures retail for my home.
What would really make sense would be to not try to fit a room’s worth of brightness into a single bulb-sized package to begin with. Instead make something like a ceiling tile covered with low-intensity LEDs, scaled such that an entire glowing ceiling would be at the right level to illuminate the room. It’d be a better quality of lighting, with no shadows, and you could also program it to do things like displaying a blue sky with white clouds, or a small number of “stars” for ambiance lighting. You might still produce the same total amount of heat, but it’d be a lot easier to manage distributed over that large an area.
But of course, that’s the sort of thing that would have to be designed into new construction, not easily retrofitted into a room that already has fixtures.
integrated fixtures are on the market, but you’re not going to get rid of decades of legacy construction (nor get everyone to throw out their table/floor lamps) overnight.
I bought new fixtures for a bedroom, and they use that concept within the fixture itself. The 9" round fixture back has a dozen or more single chip LEDs scattered about, there is no socket and bulb. They refer to it as an “integrated LED” fixture. I can’t come up with a photo that shows the inside of the light. Lots of articles, but no photos.
Dennis