What people in the LED community fail to realise is that the T12 and T8 flourescent tubes are really really good at what they do. They are very efficient, (more efficient than the production LEDs you can buy today), far cheaper to make and realitively long lifed. Until LEDs have improved their efficiency by another 50% its pointless anyone trying to make a replacement for the T12 and T8 use in general office type lighting.
In specialist lighting it does make sense but they didn't win the job on the basis of unit cost or efficiency. Unfortunately no optic will help anyone beat the T12 and T8 because using it doesn't reduce the cost over bare LEDs and it doesn't create more Lumens.
In specialist lighting it does make sense but they didn't win the job on the basis of unit cost or efficiency. Unfortunately no optic will help anyone beat the T12 and T8 because using it doesn't reduce the cost over bare LEDs and it doesn't create more Lumens.
The secret to sales success is in understanding LEDs strengths and playing to them.
Unfortunately LEDs are not yet ready to take the standard T8 and T12 on in a straight fight. Currently the wall-plug efficiency of an LED replacement is not as high and the cost is 10x more, so why would anyone want them if they haven't got some other reason to purchase it?
Unfortunately LEDs are not yet ready to take the standard T8 and T12 on in a straight fight. Currently the wall-plug efficiency of an LED replacement is not as high and the cost is 10x more, so why would anyone want them if they haven't got some other reason to purchase it?
I agree with what you have said here.
I think sometimes the problem is people coming from the electronics side into LED lighting are not all that familiar with existing lighting applications and make bad decisions on how to proceed.
The T8,T12 retrofit is a good example because a good luminaire of this type is already high efficiency (80+ lumens/watt) and fairly inexpensive with pretty good lifetimes. The optics are highly efficient for general area lighting, so there is little one can do with LEDs to improve upon the design until the LEDs far surpass 80 lumens/watt in efficiency and come way down in price. That should be obvious to those working on these replacements, but somehow it doesn't seem to get through.
Optimism doesn't pay the bills very long though...
I have to beg to differ on this - although on face value fluorescent tubes seem efficient - you have to understand the whole application to make a true comparison - an efficient light source built in to an inefficient fixture, used in the wrong application can be a disaster for energy use. - Take a look at many fluorescent downlights - the high lumen output ones often have an LOR (light output ratio) of less than 50% - i.e 50% of the light produced never leaves the fixture - A correctly designed LED fixture, even with a less efficient source can produce the same useable light for less energy.
Gordon,
I think what Ian originally was talking about was drop in T8-T12 tubes that are fitted with LEDs used as a replacement for the T8 and T12 fluorescent tubes. That's a bad application for LEDs especially if the fixture produces a bad LOR because of baffles etc..
The DOE just completed a round of testing with the T8-T12 drop ins and the performance is not so good.
http://www.netl.doe.gov/ssl/PDFs/troffer_benchmark_01-09.pdf
Even with the higher fixture efficiency from the directional LEDs, the overall fixture efficacy was still well below that of the fluorescents.
When you consider that at T-8 bulb is only $2-3, you have a really really long way to go to make the case for an LED drop in especially when they don't even perform at the same level yet.
I wouldn't disgree though that a specially designed fixture using LEDs to serve the same purpose as a T8 troffer lamp for example may very well beat the performance. But that is a different approach than the drop in bulb replacement.
Spelling!(FlUOrescant)
R.Brett-Knowles | February 5, 2009 11:36 AM | Reply
Spelling!(FlUOrescant)
I hate to pick you up on this. But I believe you spell it fluorescent. That's with an E, not an A.
very nice post... thanks!!
Well 1.0 has an end of life date now. July rather than March as you had suggested.