For the LED fanboys

[ForceFed70]

Here's a great study done by the IEEE (Institute of Electrical Engineers)

http://lumiversal.net/upload/T5 v. LED.pdf

It backs up what I've been saying on here for years - LED is not more efficient than T5 for general overhead lighting.

Another interesting find was that the LED lights they tested fell far short of the manufacturers efficiency claims. While the T5 lights had an efficiency that was just a little higher than the manufacturers claims.

While there are LEDs out there that surpass T5 in efficiency they are either super expensive or are only found in research settings. The one fixture that I did see with a marginally better efficiency (and you could actually buy it) had very poor CRI. You'd only want to use it for low quality outdoor lighting applications (accent lighting, lighting in a parkade, etc).

LEDS are a wonderful technology and there are a lot of applications where LED is the best choice for lighting technology - however, general overhead lighting is not one of those applications.

Efficiency still needs to improve and initial cost needs to come way down before LED will become a practical replacement for T5.

 

[oldestof11]

And how does it compare to T8s? Local firehouse switched from T8s to LED and saw a 20% reduction in energy use while having better lighting.

 

[188slo50]

We just switched at work, there expensive but put out great light. I guess we will see how much longer they will last compared to the others.

 

[ForceFed70]

And how does it compare to T8s? Local firehouse switched from T8s to LED and saw a 20% reduction in energy use while having better lighting.

I forget but I think T5 is something like 11% more efficient than T8. Just swapping to modern ballasts, etc could have probably put you there with T5.

 

[ishiboo]

Here's a great study done by the IEEE (Institute of Electrical Engineers)

http://lumiversal.net/upload/T5 v. LED.pdf

It backs up what I've been saying on here for years - LED is not more efficient than T5 for general overhead lighting.

Another interesting find was that the LED lights they tested fell far short of the manufacturers efficiency claims. While the T5 lights had an efficiency that was just a little higher than the manufacturers claims.

While there are LEDs out there that surpass T5 in efficiency they are either super expensive or are only found in research settings. The one fixture that I did see with a marginally better efficiency (and you could actually buy it) had very poor CRI. You'd only want to use it for low quality outdoor lighting applications (accent lighting, lighting in a parkade, etc).

LEDS are a wonderful technology and there are a lot of applications where LED is the best choice for lighting technology - however, general overhead lighting is not one of those applications.

Efficiency still needs to improve and initial cost needs to come way down before LED will become a practical replacement for T5.

Note you're referencing a study from 2010, quoting other studies from previous years, from a company selling T5 stuff. Note a T5 bulb loosesperhaps 20% of its initial efficiency over the first part of its usable lifetime.

T5 may be a bit more efficient, and it's still cheaper than LED... but LED is still the future and a darn good option now if you have the initial investment.

 

[paranoid56]

Note you're referencing a study from 2010, quoting other studies from previous years, from a company selling T5 stuff. Note a T5 bulb loosesperhaps 20% of its initial efficiency over the first part of its usable lifetime.

T5 may be a bit more efficient, and it's still cheaper than LED... but LED is still the future and a darn good option now if you have the initial investment.

exactly. it would be interesting to see a study from 2013 as so much has changed in 3 years of LED tech that they really need to be doing these every year.

 

[ForceFed70]

Note you're referencing a study from 2010, quoting other studies from previous years, from a company selling T5 stuff. Note a T5 bulb loosesperhaps 20% of its initial efficiency over the first part of its usable lifetime.

T5 may be a bit more efficient, and it's still cheaper than LED... but LED is still the future and a darn good option now if you have the initial investment.

How the heck can you say T5 is more efficient and cheaper in 1 breath but say LED is a good option now? LED is more expensive and less efficient. It's not a good option now. If you spend a mint ($500 per fixture) you can get some fixtures that are marginally more efficient but you'll never get your return on investment.

A Study from 2009 actually. But a study by IEEE which is as independent as you get (even if referenced by a company trying to sell something). There have not been any significant advances in LED technology in the last 5 years. Lots of articles about major breakthroughs in labs... lots of articles about some new LED that's even more efficient. Yet nothing that actually has hit the market. Seriously - go back in time 5 years. What you'll find is that with the LEDS available now - there are some that are slightly more efficient than 5 years ago (less than 10% more) and you can find LEDs in larger die sizes now (5W and 10W). That's it... there's been no advances that have actually made it to market for one reason or another.

Actually - I've studied the lifespan curves in depth. T5 has the advantage here. They keep their intensity over their lifespan much better than LED. T5 lamps are also replaceable and relatively cheap to replace. LED fixtures - most do not have replaceable lamps and the few that do literally cost hundreds of dollars to replace. No advantage here.

Why do you say LED a good option? Any angle I look at it T5 has the advantage.

 

[ForceFed70]

exactly. it would be interesting to see a study from 2013 as so much has changed in 3 years of LED tech that they really need to be doing these every year.

People keep saying this. There have been no advancements - at least nothing that has hit the market. Just press release after press release by some group of scientists looking for bragging rights.

Seriously - identify a single major advancement that has happened in the last 3 years that has actually left the laboratory. The only advancements I've seen have been around application and the development of larger single LED dies. But these have been advancements in application - not the technology itself.

Baby steps - it's all I've seen.

 

[Iggi]

I have been making and selling led lights and fixtures since early 2000s back when the first high power Luxeon I hit a whopping 25 lumens running at full spec. By "making", I mean i buy leds, buy US made electrical components for drivers and buy large chunks of aluminum that i turn and mill myself to produce leds lights. I sell led lights for home/outdoor use, off road lights for the 4x4 guys, marine lights for fishing, motorcycle aux light, aquarium reef lights and lights for the biking community. I get all the industry newsletters and i stay pretty up to date on what is developed.

While it is true the technology might be the same from ten years ago, it is inaccurate to say there have been no advancements within the technology itself. Its like saying the space shuttle is pretty much the same and only slight better than the Wright brother's plane. Here is an example. Back in 09 when the study was conducted, I was building a triple led light using three cree XRE running all three at 1 amp to produce about 600 real lumens. It took a 6 ounce finned piece of aluminum housing to keep the whole thing from cooking and it was it was forced cooled by moving air. My current triple led light has three cree xpg II leds running at 1 amp producing 1200 lumens using a 1.8 ounce finned housing to keep everything cool. Now there are single leds capable of producing over 1000 lumens. When cree or luxeon or seole announce a new led development, i can have that led in my hands usually in less than 6 weeks.

The main problem with the 2009 study is the commercial lighting available at the time was still in its infancy and pretty terrible compared to whats available now. Back then the lighting industry was still in the late stages of denial as to how leds were going to take everything over. The higher cost of led fixtures is not the leds themselves but the drivers. I can buy the hottest leds available now for $10-$15 but a US made, reliable AC driver i need to drive it cost me $25-$40. The same driver made in china using crappy components costs $4 but will barely last a year.

As for the document you posted quoting the 2009 study, the information contained within is as relevant now as an ancient scroll claiming the earth is the center of the universe. The only part of the study that still rings true is that led fixtures are still more expensive than traditional lighting but the spread is not as much as it was before. The prices keep dropping and the efficiency increases every 6 months. Led fixtures are everywhere now and the proliferation will continue unabated until something better comes along. Fluorescent lighting will go the way of the halogen bulb in a few years.

 

[mayday0017]

Yep 2010 study is not any where close to right today.... Cree LED's weren't really around in 2010, the LED's we have today are WAY better like 10x better.

Good read though!

 

[Stuart in MN]

I had a recent design project for a municipal wellhouse, where at the owner's request we used LED ceiling fixtures instead of fluorescent.

T5 and T8 fluorescent lamps are typically rated for around 20,000 hours, although there are some long life versions out there that are rated for more than 30,000 hours.

The LED fixtures we used are rated for 100,000 hours. The upfront cost is more than fluorescent fixtures and they only use a little less power, but the reduced maintenance and longer life will offset the cost.

This was an unusual situation; for most interior lighting designs I'll continue using fluorescents for the time being, but LEDs in fact have come a long way in just the last couple years. We do use them regularly on building exteriors (wallpack lighting that goes over entry doors) and are using them more and more for streetlighting projects - in fact I just finished up an LED streetlight project for a local city, and they're very happy with them.