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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthortony
    • CommentTimeSep 29th 2018 edited
    LED lights produce more UV than the luminaries that they replaced.

    This could give rise to several problems

    1. UV light can produce ozone and I reckon that indoor ozone levels will be higher than previously (ozone goes on to produce NOx which is also harmful) I have yet to see this reported but do think very many people measures indoor ozone levels as they have never been a problem.

    2. UV light can cause eye problems, as can looking at or glimpsing very bright lights, I expect we will start to hear about these in the coming years.

    3. Light that has a higher UV portion than previously, the type that emanates from LED street lighting has already been reported in Spain to increase risk of melanoma - how long before we start to get reports of this problem for indoor LED lighting?

    The recent rapid change over to LED lighting could have other unforeseen side effects.
    • CommentTimeSep 29th 2018 edited
    tony opined: 'LED lights produce more UV than the luminaries that they replaced'.

    Do you have some evidence? Doesn't it depend on what they are replacing? And wouldn't it be the lamp rather than the luminaire that was important?

    See e.g. https://www.linkedin.com/pulse/led-lighting-uv-question-chad-randall http://www.premierltg.com/do-led-lights-produce-uv-led-tanning-beds/
    I'd understood that LEDs produce less UV than incandescents, and substantially less than fluorescents. You don't see LED sunbed salons!

    But this is anecdotal. Has anyone got any real data on this?
    • CommentAuthorRobL
    • CommentTimeSep 30th 2018
    Most white leds actually have monochrome blue led chips, and a phosphurescent coating that smears out some of the blue into lower energy greens and reds. The difference between warm and cool white leds is all in the phosphur. The phosphur cant make higher energy UV, nor can the blue led.
    Here's a pic(too big, see the orig link):
    • CommentAuthorfinnian
    • CommentTimeSep 30th 2018
    It seems a bit weird frankly to try to jump from 'LEDs produce some UV' to 'there might be a problem with ozone production'. Ozone production actually requires very short-wavelength hard UV light (~180nm) to start with. Even LEDs designed for UV production are at the long wavelength end at ~350nm.

    It is very easy to come up with 'a list of concerns' but unless there is actually some evidence that any of these concerns are actual issues, it seems a bit scaremongery. Of the genre 'I don't like LEDs, so lets make up some vaguely plausible reason that they are bad'. No doubt changing over to LED lighting will have some health implications, but making a whole bunch of unsupported speculation seems pretty irresponsible.

    As for looking at really bright lights, there is quite a big dangerous one in the sky. I know Australia has a big problem with eye conditions due to sun exposure. Actually in the UK vitamin D deficiency due to not enough UV is the big one. But LEDs dont produce UVB anyway.

    As for the spain business, claiming that LED lights in Spanish street lighting create the same kind of UV that causes skin cancer, and therefore we should worry about it, is tending towards innumerate: the important thing is the dose. Solar illumination is about three orders of magnitude stronger than street lighting. Unless you can quantify the risk, you can't have a sensible discussion.

    You can find various images showing sunlight spectra compared to LED spectra like the one in RobL's post: for the same amount of illumination, LEDs have much less UV than sunlight (they also produce much less UV than fluorescent bulbs). And sunlight is vastly stronger than indoor lighting.
    • CommentAuthorCWatters
    • CommentTimeOct 3rd 2018
    Rather a crude test but perhaps effective. Shows very little UV from incandescent, halogen or LEDs. Avoid CF.

    • CommentAuthorCWatters
    • CommentTimeOct 3rd 2018
    I suspect the sun is by far the biggest source of UV light.
    • CommentAuthortony
    • CommentTimeOct 4th 2018
    I agree thanks for alaying my slight worries all
    Actually Tony, the high blue component of the spectrum is a concern for human health as it interferes with circadian rhythms. This is why phones etc. now have a "night shift" mode to reduce the blue components. For municipal street lights, 3000K should be the maximum colour temperature used - even this is high and best practices are moving towards 2700K or lower - better still is "pure amber", which is similar to sodium street lighting, though people moan about the poor colour rendering.

    Paul in Montreal

    ps I will paste in some links to some presentations (largely in French) that were given to our local community by experts in the field (one of whom is involved in the Lac Megantic Dark Sky Reserve in central Quebec)
    • CommentAuthortony
    • CommentTimeOct 11th 2018
    Thx I agree about the colour temperature spectrum, looks like Canada is ahead of the UK on this
    Here's two presentations that were given at EarthHour events in our community:

    Les DELs bio-inspireĢes: EĢvaluation et optimisation de la technologie en accord avec la biodiversiteĢ
    Johanne Roby 1, Arnaud Stolz2, Sophia Zerouali 1 et GenevieĢ€ve Lacroix 1 Projet collaboratif CeĢgep de Sherbrooke et UniversiteĢ de Sherbrooke
    1-CeĢgep de Sherbrooke 2-UniversiteĢ de Sherbrooke

    Link to PDF: https://drive.google.com/open?id=0B0TKRAjRmhyUR0thT3A4NzBaWHBKclNfbTlFa0QyRWI0V2ZV

    Light pollution and its impact on human and animal health
    Johanne Roby, professeur de chimie CeĢgep de Sherbrooke Groupe de recherche sur la lumieĢ€re

    Link to PDF: https://drive.google.com/open?id=0B0TKRAjRmhyUQzdGWF84b2xEUFByNUN3RHlxdTZpaE14Qk1V

    It's also worth following Dr John Barentine ("Dark sky warrior. Policy nerd. Astronomer. ") on twitter: https://twitter.com/JohnBarentine - he has LOTS of great information about dark skies, LEDs etc.

    Paul in Montreal.
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