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Re: Shop LED Lights

 

Mark as far as the lumen rating goes I was just using the manufacturers specs for comparison, Phillips for the T8's I use and Hyperikon for the lights Jason used. When I tested the actual output, the LED tubes I tried were rated at 2000 lumens and showed the equivalent?light loss compared to the Fluorescent?T8's 2450 lumens. The test was done on my slider so I could see the transition and light change over the range of the slider. I also changed out the 12 of the T8's in the area for new bulbs and found no difference in output after approx 15000 hrs of use at all according to the light meter. Again this can be taken for what its?worth as who am?to disagree with the?light Gods,?LOL. If and when I can change out my bulbs to LEDs with no loss of light I might? consider it for the small decrease I would see in my power bill. For now I intend to replace 2 more of the 8' 4 tube T8s with 8' 4 tube T5HO for double the light output to help with my aging eyes.?

Mike the heat output for me with an 11' ceiling isn't an issue especially since the cool months far out way the extremely hot days here. My $250.00 Window Shaker air conditioner keeps the shop at a nice 75 degrees on the hot days we are getting now. Now for Joe and others in a hot area it most definitely is a consideration.

On Sun, Jul 26, 2020 at 2:39 PM mark thomas <murkyd@...> wrote:
John,

Your model assumes greater efficiency gain than mine, thus requires fewer bulbs needed to achieve the same savings.

You're replacing 32W with 18W, a 45% efficiency gain.? A modern 32W T8 produces around 3000 lumens, almost 50% more than a 18W LED T8.? Your model also assume a loss of lumens, from 2450 to 2100 per tube.?

I held lumens constant, so I assumed the old tubes to be 25W, which has same lumen output as 18W LED, yielding a 28% efficiency gain.

LED T8 marketing often describe 18W LED T8 as "equivalent to 32W fluorescent" or "replaces 32W fluorescent".? ?I believe the basis of this claim is a notion of "effective illumination", assuming the directionality of LEDs yields less wasted lumens.? But in actual lumen output, a 18W LED is ~70% of a? T8 fluorescent.

The details make a non-trivial difference, for example the type and quality of reflectors, location of fixtures, etc.

A 30% efficiency gain per se seems attractive, but context matters a lot.? Obviously that's huge for 5 million square foot office tower.? For a small shop in cold climate (where one is using the waste heat), it might be barely measurable in reality.?

Btw, I am guessing Jason didn't charge himself for his labor.? If it takes half hour per fixture and labor is $100/hr and he had 30 fixtures, that's $1,500, moving the payback from 1 year to ~2.5 years.? ??



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John Kee
JMK Services
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