formula for converting Metal Halide Lux to LED Lux

[mstarcom]

We are looking at replacing 10 x 1000W MH fixtures in our table tennis club.

Since a maintaining a quality lighting level is IMPERATIVE, I have taken readings at all the tables to compare current lighting levels with those on the projections provided by some prospective vendors. We currently average 1000 lux in the gym, with the darkest table 700 lux, and the brightest 1400.

I know that LED lumens appear brighter to the eye, but I do not know the conversion formula. Our current bulbs have a color temperature of 4,200 and CRI of 65. What conversion formula should I use to ensure that the new lights meet our requirements?

 

[degarb]

Not true. It really depends wholly on the reflector. It is like asking what flashlight throws further. I have two 150 Watt metal halides inside my garage. They retail at some insane price but have such poor reflectors that I have never brought to any serious job. Then I have three wing reflector (parabolicish) grow lights that I just tested against my 50,100,200,500 Watt led lights. Not only does their lux per lumen match led v. MH (2x the halogen lux per lumen) but they are using epistar 80+ lumen 70 cri class leds, and seem to be topping out at 65 lpw after driver and glass loss.

That said, led eventually will kill the mh once higher cri and efficient leds can be cost effectively belting out 40k+ lumens. The technology is here, but too expensive in larger lights. My 1000 watt mh is an easy 130 lpw lamp level. My 400 Watt mh puts out 42000 lumens, electronic ballsted, 4k lux at 5'8" . while my new 22lbs 500watt led seems about 30k lumens at 3k lux 5'8"
Same lux per lumen. Now if a 29k ceramic mh is same as a 40k 65 cri mh, then the cri weight is 2.3. I am see this cri weight factor comparing other lights. I will post link to an article and the spread sheet that sparked a suspicion of this factor, which I am sure fails to take all factors. Link to follow tap a lost-phones are killing post quality.

 

[degarb]

http://arklighting.co/2013/10/comparison-of-led-v-other-light-sources-including-hid/

Spread Sheet CRI calculator attempt : https://drive.google.com/file/d/0ByvnKHNhvrTmc01hUlE4aWo5TWM/view?usp=sharing

 

[degarb]

So, fresh, your 10 mh lights put out a true 1.1 to 1.3 million lumens, depending on setup. (I write "true", since most led lamps exaggerate the lumen number. ) mh really rock above 600 Watt as the efficiency goes up. Imho, led route you would need deep pockets to match the mh. Cree cxb3590 $60 for 100 Watts, plus driver massive heat sinks, and I would wager less end lamp efficiency than the 1000 watt . the higher cri I would wager, would just balance against the lower efficiency. You might gain lumen maintenance and colors would look more saturated.