I plan on placing a Metal Halide 1800 watt bulb 20 inches in front of me (not exactly in front but over my head) - will this produce more heat than I can handle?

Someone said the question was vague so I'm adding details: The purpose of this experiment is to generate 40,000 lux of light in my immediate surroundings (basically to reproduce outside lighting conditions indoors). This is why the bulbs need to be placed so close to me. If I had put it 40 inches away, for example, perhaps there'd be less heat to deal with, but the amount of light reaching me would be cut in half which means I'd need to add more bulbs. With more bulbs I would have more heat and (I guess) run into the same problem?


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    \$\begingroup\$ Just a note, if you put it at double the distance, you actually get ~1/4 of the light and heat due to the surface area of a sphere equation being with respect to a square term. \$\endgroup\$ – horta Mar 19 '15 at 4:22
  • \$\begingroup\$ Why don't you use a mirror to try and move the light further away from you if it doesn't work out? In that way, you'd only get infrared heating rather than all conduction, convection and radiation. \$\endgroup\$ – horta Mar 19 '15 at 4:23
  • \$\begingroup\$ Mirrors would increase the light intensity by at most 50% (but probably more like 20%) so the fundamental problem would remain the same.. i.e, I'd be burnt instead of "fried".. \$\endgroup\$ – Michael Morl Mar 19 '15 at 4:26
  • \$\begingroup\$ At any rate, how much heat it gives besides visible light I gave in my answer. How that affects the body is more of a biological or physics question. I don't think you'll get much more information from here. \$\endgroup\$ – horta Mar 19 '15 at 4:29

1800 Watts at 25% efficiency means 75% is wasted or 1350 watts is being radiated as heat. Let's be very very inaccurate and say 1/4 of that heat is heading towards you. That's 337 watts of direct heat to you. The human body produces 100 watts of heat on its own. You've just added 3X that amount.

If you're already in a room temperature environment (70F), then yes, you'll get toasty fast. If you're in a 40-50 degree room, it might actually be somewhat comfortable on your face, although your feet will probably go numb.

Keep in mind that these numbers are extremely rough and there's a lot of guestimates in here. I would say my margin of error may be around +-100%...

Ask a vague question...get a vague answer I guess. Hope it helps a little though.

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  • \$\begingroup\$ yes, it certainly helps. How many degrees would 337 watts increase body temperature by? And why would feet get numb? I added some details to question, if it's still vague please let me know.. \$\endgroup\$ – Michael Morl Mar 19 '15 at 4:02
  • \$\begingroup\$ @MichaelMorl Should have answered your q's here. 337 watts increases body temperature dependant upon the environment (that was the 40-50 degree part of the answer). You'd get numb in the feet because your face/shoulders would get a lot more heat than your feet meanwhile the hypothetical 40-50 degree room would be cooling your feet off making them cold enough to get numb. \$\endgroup\$ – horta Mar 19 '15 at 4:44

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