question in Building Construction Illustrated (1)

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lotus0418

February 09, 2021 00:10

Hi guys, I have some questions about below image:

1. For the form in the above, the color rendering index goes down for different type of lamps. Does this mean the cool-white and warm-white fluorescents render color not very well. But this doesn't make sense as we really do painting or drafting under these two kind of lamps.

2. For the chart in the below, I cannot see any relationship about some curves with the designated types of lamps. Foe example, the curves of the cool-white and warm-white fluorescents are the same. I think the cool-white fluorescent's curve should have a peak at short wave light, but it doesn't.

So I hope someone can kindly answer my questions. Many thanks in advance!

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  Joseph February 09, 2021 10:59

  #1. watch this.

  https://www.youtube.com/watch?v=0Az05_jzgNw

  #2. What this graph tells are how efficient each light fixtures are in comparison. so it is more efficient toward bottom-left & less efficient toward top-right. (I recommend watching amber video!.)

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  lotus0418 February 10, 2021 22:49

  Dear Mr. Cho,

  Thanks for the video for #1 question. It's very helpful. For #2 question, I didn't subscribe amber video so can you explain here or is there video on youtube also? Many thanks!

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  Joseph February 10, 2021 23:38

  video @ #1 is the part of amber video on youtube (free).

  the curves illustrate how partial wavelengths fluorescent fixture produce compared to incandescent fixtures and even more to sunlight. when the wavelengths are even, it is closer to sunlight which has high CRI.

  for some reason, curves in incandescent show more even wavelengths than fluorescent but lower.

  focus on number below CRI in your image & amber video. fluorescent is CRI 85 which is pretty high.

   

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  lotus0418 February 16, 2021 20:36

  Hi Hang,

  Thanks for your message. But I still have questions about the chart. I see the curves of the cool-white and warm-white fluorescents are the same. I think the cool-white fluorescent's curve should have a peak at short wave light (cold light), but it doesn't.

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  Joseph February 22, 2021 00:09 (Edited February 23, 2021 00:00)

  Yes -  the cool-white fluorescent's curve have a higher peak at short wave light (cold light) - look close.

  Here is another resources.

  http://www.lamptech.co.uk/Documents/FL%20Phosphors.htm (just look at colored graph & compare warm white 29-530 vs cool white 33-640)

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