Are all lumen outputs equal? Specifically T12 to LED comparison?

[CarCrazyRDM]

Basically is a lumen a lumen or are there other mitigating factors based on bulb type?

I ask because I know I had six dual 8ft bulb T12 high output fixtures in my previous garage. Those bulbs were rated at 3400 lumens each I believe. At my current house where I have built a 24x36 garage/shop I am considering going with the LED T8 conversion fixtures that Platonic Solid has recommended in this thread: The Best Light Fixture

My old garage also had roughly 13 ft ceilings (same as my new shop) and it was approximately 24x24. So ultimately what I am trying to determine here is if the lumens per sqft in my old garage with T12's is comparable to a Lm/sqft calculation in my new shop with LED bulbs.

My old garage came out to be between 70-75 Lm/sqft and if I "only" go with the 30 bulbs/15 fixture combo from the above link then my average for the new shop comes out to be around 67 Lm/sqft. I just want to know if I am comparing apples to apples here. I know my last garage was plenty bright but I also wouldn't mind the new garage being a touch brighter, or at least having the option to make it brighter (different rows of lights on separate switches).

So is this a fare comparison or does how the light disperse or any other variable skew such a comparison?

Thanks in advance for any info.

 

[06switchback]

I have 6 4ft leds in my 24x24 garage they are from home depot I forget the brand but they are plenty bright I think they are about 3200 lumen each and they were the cheapest I could find I think they are very equal to a 2 lamp flourecent

Sent from my SAMSUNG-SGH-I537 using Tapatalk

 

[zendriver]

I know my last garage was plenty bright

the comparison between the two, is kind of "apples to oranges", IMO.

Florescent radiate at 360 degrees, so the fixture, even the ceiling itself have a factor, in overall lighting quality.

LEDs radiate at something less than 180 degrees and although the tube they are in, disperses light, they seem to be less reliant on the reflective quality of the fixture itself, IME.


When I converted (and finished) the lighting in my garage, the florescents were ancient, so it is not the same comparison, as your situation, but the lighting improvement, from the new LEDs, is phenomenal.

 

[CarCrazyRDM]

Thanks for the input guys.

And maybe what I also should have said was that based on some other reading on this forum I'm thinking maybe I should be shooting for 100+ lumens per sqft. So I was kind of hoping the disbursement of light via LED bulbs was more concentrated (less than 180 degrees as zendriver mentioned) compared to fluorescents which may "waste" some portion of their light shining upwards and to some degree to the side. Meaning 70 Lm/sqft coming from LED's is actually going to measure brighter at floor level than 70 Lm/sqft coming from fluorescent bulbs.

Does that make sense? Is that true?

 

[DC73]

So I was kind of hoping the disbursement of light via LED bulbs was more concentrated (less than 180 degrees as zendriver mentioned) compared to fluorescents which may "waste" some portion of their light shining upwards and to some degree to the side. Meaning 70 Lm/sqft coming from LED's is actually going to measure brighter at floor level than 70 Lm/sqft coming from fluorescent bulbs.

Does that make sense? Is that true?

Lumens are lumens but, as you've alluded to, the lumens at floor level and the quality of light are highly dependent on the design of the fixture and lamps. That's why the pros use lighting design software.

You can use this online tool to compare some fixtures: http://www.visual-3d.com/tools/interior/default.aspx?id=14782

Not sure if you can manually add other fixtures to the database. Been awhile since I've used it.

Good luck.

DC

 

[Showkey]

Or novice or amateur can use a smart phone app to measure LUX.
Which allows you to measure light at the work surface and allows you make valid comparisons between fixtures or bulbs.

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[CarCrazyRDM]

Showkey, thanks for the app idea. I may give that a try just to get a general idea.

DC73, I briefly played with that online lighting a few weeks ago but found myself more confused that feeling like I'd come to any conclusion about what was needed, lol. Maybe I'll give it another try though.

 

[cybrdyke]

Thanks for the input guys.

And maybe what I also should have said was that based on some other reading on this forum I'm thinking maybe I should be shooting for 100+ lumens per sqft. So I was kind of hoping the disbursement of light via LED bulbs was more concentrated (less than 180 degrees as zendriver mentioned) compared to fluorescents which may "waste" some portion of their light shining upwards and to some degree to the side. Meaning 70 Lm/sqft coming from LED's is actually going to measure brighter at floor level than 70 Lm/sqft coming from fluorescent bulbs.

Does that make sense? Is that true?

Lumens per square foot is not a valid criteria. It doesn't work, so dont try to use it to determine the amount of fixtures to use.
Fluorescent fixtures only deliver about 60% (it varies greatly) of the rated lumens of the lamp. LED normally delivers 90% or more.
You need to determine how much light you want...in footcandles. A well lit working shop or detail shop can be as high as 80-100 fc. A typical residential garage can be 40-ish. Just storing cars would require around 20. Choose your level and then ask someone to do a photometric layout for you. And dont buy the cheapest **** you can find. In LED, you get what you pay for.
Good luck,
CD

 

[Rickss96]

OP - you may find this article on lighting the shop useful.
http://www.sawmillcreek.org/content.php?146-Lighting-the-Small-Workshop-by-Jack-Lindsey

Written by a lighting engineer for woodworkers to use for their shops, it is a simplified approach and contains some useful definitions and recommendations for the amount of light you need at the work surface. And he defines this in footcandles as cybrdyke strongly recommends.
Unfortunately it is an older article and focuses on fluorescent fixtures; LED types were too new at the time for him to consider.

But there is still some good advice here on layout and other issues that apply to your problem. Good luck