LED replacement for T8 fixtures a few thoughts

[reible]

I'd like a few of you to look this over and see if my thoughts sound right. Right now I feel confused about how I went about this and while I'm not interesting in the exact math portion I would be interested in the construct. At this point lets call the math fluffy.

While in the hardware store the other day I noticed that they had LED bulbs that fit in place of the 4' florescent tubes like I have in my shop fixtures at home.

I have not researched this online but the ones the store had were specked like this.

17 watts
5000K
lumens 1950
life 50000 hrs
$29.99

The 17 watts looked interesting, about half my current bulbs.

The color temperature I like in the shop is 6500K but maybe I could live with 5000K?

However unlike other LED stuff I purchased they seem wanting at 1950 lumens, the lights I use are good for 2400 lumens.

The cost is the real killer, $29.99 while I pay $3.33. Well some of that comes out in the wash as the LED work for 50,000 hours while the other are good for only 18,000 hrs.

To get more into the process I said well if I use 50,000 hours as a starting point then I would need to buy 3 of the 18,000 bulbs to get at least to that point. The 3rd bulb would still have time on it when we get to the 50,000 hours but I didn't want to deal with that. Simple math says the bulbs (3 at $3.33) = about $10.

For things to be even, if I'm thinking about this right is the difference in costs of the bulbs has to be made up for in electrical costs. So if the bulb lasts for the 50,000 hours and I multiply the 17(watts) * 50000(hours) then divide by 1000(kwatt) this would leave me with the kilowatts used, about 850. Our current rate is $.08 so a cost of $68.

Using the same thinking (32 * 50000)/1000 = 1600 or about $128.

If we add the total cost of the LED bulb at $30 and usage $68 or a total of $98. The existing bulbs would be $10 and usage of $128 or a total of $138. The LED bulb would save $40 over its life.

The savings would start after about 7 years, so if things don't go that far it would not be much of deal.

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50,000 hours is a long while. If I have the lights on 6 hours a day it could be on for 8333 days, or about 22.8 years. Might well be longer then I need them....

My shop has 22 bulbs so it is unlikely I will be doing a swap out of all of them, at least not at $30 a bulb, or $660. If the prices get down to say $20 a bulb it still would be expensive but getting closer.

So what errors have I committed?

Ed

[BuckeyeDennis]

A quick read didn't catch any errors, but perhaps a couple of omissions.

1) The LED bulbs have only about 80% of the light output of your standard bulbs. So you'd need 25% more of them (fixtures too) to get the same illumination. For a fair comparison, I'd calculate the cost per lumen-hour, rather than the cost per bulb-hour.

2) Time cost of money. You have a pretty steep capital investment in the purchase of the LED's. That money could be earning interest (albeit not much at current rates), or appreciating in the stock market. That lost income should be added to the operating cost of the LED bulbs.

[benush26]

Ed,
though I don't see any ommission I would comment on the possibility of a false economy. I recently purchased these from Costco at $39

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They are 38 watts, 3700 lumens, 4100K.

I am not suggesting that you replace your shop lights with these only that for the price you would be paying for less brightness than these in your replacement bulbs, you should be paying significantly less.

I believe Dennis' time/cost benefit factor is applicable in that by keeping your money in your pocket, a brighter replacement (at probably a much lower cost) should be available within months.
I've been checking out a 7000 lumen LED fixture which just 3 months ago was $500 and is now at $300.
I decided to use the Costco lights for general shop lighting. I've put a significantly brighter 4 footer just above my main work bench and will supplement the main area where I have the saw with a similar one. Basically only using the brightest light when I need it.

So.... if you are looking for savings in usage, procrastinating might change the equation significantly.

So yes, yet once again, I do not adequately address the exact topic, but hope to affect an underlying theme. And give you yet more to ponder!

Be well,
Ben

[algale]

i read somewhere that these LED bulbs have something like a 110 degree angle over which they disperse their light versus the 360 degree angle of a typical flourescent So, how does that change (or does it) the lumen comparison of these bulbs? Lumens directed to my ceiling don't do much good.

[mountainbreeze]

My concern with the (expensive) LED bulbs is their actual longevity. I fee I have been bitten by the longevity claims of CFLs and I find myself wondering if the same thing is going to happen with LEDs. It doesn't bother me much when a $3 bulb lasts only 50% of its expected life but it's a different matter for a $30 bulb.

[beeg]

Is this all worth the time and effort to save $1.75 a YEAR for less light and color temp?

[Gene Howe]

We have replaced almost every CFL or incandescent bulb in the house with LEDs. Things are certainly brighter. We used 100 watt equiv. to replace 60 watts in most situations because heat isn't a huge factor with LEDs.
So, I was considering replacing my 8' T8s in the shop but waiting until the 8' become more readily available (read cheaper).
However, I'd really like to see, in person, a large shop or large garage installation to gauge for myself if they would really increase the brightness enough to justify the switch.
The most important factor for me is brightness. Second is longevity. I'm not really too concerned about color rendering or cost per lumen.
At 75 yr.s of age, I might not ought to be too concerned about longevity, either.

[reible]

I went back to thinking over the lumens and since I'm pretty happy with the lighting I have, a total of 22 bulbs at 2400 or about 52800 lumens I would indeed need to add more fixtures and bulbs. Using LED bulbs that would be more like 28 needed. That plus 3 fixtures to ceiling, which would mean moving what I have around to spread the light around. More work to do....

I had not written down the color rendering numbers, I like bulbs with a high number, from memory the ones I get are 94. The LED replacements are I believe 80.....

It would seem that the tangible aspects for everything but long term cost favor the existing system I have. Factors like real life of the bulbs does present questions in figuring that long term savings. On the other hand raising electrical costs might out weigh even that.

The other factor that I had not looked at was the decreased output of the bulbs over life. I know when I replace bulbs the new one is always seems brighter, well yes the one is dead and the new one is working but I'm talking more about when it had reached old age verses new. LED's I expect don't have that issue.

I do believe I've talked myself out of going to LED replacements for now. Might revisit it again next year when things might look different.

Thanks everyone for you input.

Ed

[benush26]

We have replaced almost every CFL or incandescent bulb in the house with LEDs. Things are certainly brighter. We used 100 watt equiv. to replace 60 watts in most situations because heat isn't a huge factor with LEDs.
So, I was considering replacing my 8' T8s in the shop but waiting until the 8' become more readily available (read cheaper).
However, I'd really like to see, in person, a large shop or large garage installation to gauge for myself if they would really increase the brightness enough to justify the switch.
The most important factor for me is brightness. Second is longevity. I'm not really too concerned about color rendering or cost per lumen.
At 75 yr.s of age, I might not ought to be too concerned about longevity, either.

Gene,
This is one of two lighting systems I have been drooling over for a while. Both have reduce their price significantly in the last 6 months. Still a bit to pricey for me, but If they come down farther .....

http://www.bigasslight.com/products/garage-light/

13000 Lumens 5000K

If you watch the video, turn off the sound. Their is only "dramatic music", no monologue not description.

Be well,
Ben

[Ed in Tampa]

I was in SAMs Club and they have the 4 ft units for $35. The lumens were listed at 5000 and each one was made to plug in. I now have 5 4 ft fluorescents 2 tube in my shop now. I'm guessing 10 of the led units would replace them.

I would replace each hard wired light with a receptacle and plug two units into each one.