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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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    • CommentAuthorrevor
    • CommentTimeMay 15th 2020
    No one seems to mention luminance i.e how much light is given by the LED. I do not know how it equates to the examples of wattage given in the comments but I have fitted Collingwood Halers a 7W unit gives out 700 lumens. These units are a complete unit mains driven cannot change the LED they are easy to fit IP 65 and fire rated. They have their own built in quick connection box the box it comes in can be used as a decorators box so the fitting can hang down from the ceiling and protected from the paint. I chose these after looking on electrician forums and these fitting were coming up as one of the best. Was also driven at the time by reports of fittings made in China being dangerous as if you fitted the "bulb" the wrong way you could get an electrical shock. The halers have a 7 year warranty and likely after 7 years there will be newer version but Collingwood will repair the unit that failed. They are not cheap in monetary terms at £20+. In all I have fitted about 150 or so of them. I needed very reliable units as in places have high ceilings awkward to reach. I have wired them in switched gangs sometimes of different colour temperature so can chose what light we want in a particular part of a room. All lights of a particular colour are consistent so don't get an odd looking one like you do with bulbs.
    • CommentAuthorMike1
    • CommentTimeMay 16th 2020
    Another thing to look for, ideally, is the Color Rendering Index (CRI) - a comparison between how colours look when illuminated by the light, compared to how they look in daylight. A CRI of 100 means that the colours would look identical, and above 8o is good.

    I say 'ideally' because the CRI for many lights isn't available. In which case it may be worth buying a couple to compare them.
    • CommentAuthortony
    • CommentTimeMay 16th 2020
    I much prefer warm white or low temperature spectrum ones
    • CommentTimeMay 16th 2020
    Posted By: tonyI much prefer warm white or low temperature spectrum ones

    I prefer the colour temperature that suits the application. And that depends to a great extent on the degree of illumination. If you want to supplement daylight, just to get better visibility in some dark corners for example, then you need high levels of brightness and a daylight (6500 K) lamp is best - almost unnoticeable. They're also slightly more efficient. If you want a fairly low level of illumination (in a 'romantic' corner, say) then a warm white (2700, 3000 K) lamp is good. If you want good general bright light at night-time, in a kitchen say, then I find the intermediate 4000 K lamps are good.
    • CommentAuthorMike1
    • CommentTimeMay 17th 2020 edited
    Colour temperature isn't the same as Colour Rendering Index.

    Colour temperature is the warmth or coolness of the light source; CRI is about how accurately an object’s colour appears when illuminated by that light.

    To take an extreme, a low pressure sodium street light - one of the yellow ones - has a very warm colour temperature - around 1700 K. However it only outputs light at very specific wavelengths - the CRI is so bad it's negative (around -44) - and almost nothing appears as it would in daylight, but only in a range between yellow and black.

    Even if you like a warm while LED of around 2700K, it may have a CRI of anywhere between 70 and 90+.

    Maybe think of colour temperature as the whiteness of white, and CRI as the muddiness / clarity of colours (lower CRI = muddy colours; higher CRI = clearer colours).
    • CommentTimeMay 17th 2020
    Posted By: Mike1Colour temperature isn't the same as Colour Rendering Index.

    Agreed, and I for one know the difference. It's difficult to tell from Tony's lamentably laconic post whether he mistook the terms or simply started talking about a different subject.

    I hadn't realized a CRI could be negative, so thanks for that! FWIW though, the CRI isn't measured against daylight but against a black body source with the same colour temperature. Otherwise warm white incandescents wouldn't score anywhere near 100 IMHO. Firelight is nothing like daylight.
    Posted By: Mike1Even if you like a warm while LED of around 2700K, it may have a CRI of anywhere between 70 and 90+.

    I've not seen any lamps with a (claimed) CRI below 80 in some years (and most reputable brands state this now).

    Temperature still seems all over the place. My spots and LED strip were both meant to be 2700 but there's no way the (what was meant to be premium quality) LED strip is even close.
    • CommentAuthorwookey
    • CommentTimeMay 22nd 2020 edited
    Posted By: revorNo one seems to mention luminance i.e how much light is given by the LED. I do not know how it equates to the examples of wattage given in the comments but I have fitted Collingwood Halers a 7W unit gives out 700 lumens.

    100 lumen/W is good. And seems to be where decent lighting has settled. You shouldn't use anything under about 70 lm/W IMHO. Check whether quoted numbers are bare LED or whole fitting. The driver and the optics both lose something over the raw efficiency of the LED. Crummy drivers can be down to 60% efficient.Good ones are 80-95%.

    In all I have fitted about 150 or so of them.

    Erm, I hope that's in multiple houses? Or do you live in a medium-sized castle? That's a kW of LEDs or 100,000 lumens which is enough for about 80 normal-sized rooms.
    • CommentAuthorrevor
    • CommentTimeMay 22nd 2020
    Yes Wookey seemed a lot so been and counted them all comes to 139 so not far out. Yes have a big place and big rooms vagrancies of the planning system had old farmhouse nothing of merit in it but because it was habitable were not allowed to knock it down so we built around it as close to a passive house as we could. No original walls exposed to the elements and the front which would have been is EWI and clad. So much bigger than we wanted and a lot more costly. The redeeming feature we inherited was the thermal mass of the stone. Could have been a lot more of an eco build than it is but end result it is a very energy efficient and well built house. (Not quite finished though)
    • CommentAuthorCWatters
    • CommentTimeJun 5th 2020
    We use quite a few GU10 LEDs.

    I always look for LED bulbs that state on the packaging they produce 400 Lumens or more. I find these are roughly as bright as 50W GU10 halogen bulbs BUT they are not quite as bright as 50W MR16 halogen bulbs. If you are used to MR16 Halogen I recommend GU10 LEDs should be installed on a slightly the closer pitch or look for perhaps 500 Lumen bulbs if you can find them.

    I also prefer wide angle LEDs that have a beam angle (over 90 degrees). I find these give much more even lighting with fewer shadows than narrow angle bulbs (typically 35 degrees). Wide angle bulbs can also appear brighter than narrow angle because they produce more glare (By glare I mean light coming directly from the bulb into your eye).
    • CommentAuthorRex
    • CommentTimeJun 11th 2020
    Thanks for the comments. I am starting to wonder if the high lumen output is basically beyond the actual design limits of the average LED (diode (or whatever it is.)

    I did manage to buy some bright ones, but found that they are 6000k when I wanted 2800k. Not surprisingly, they would not take them back. However, I have some cine lighting gels some have converted back to 3000k by levering off the cover and putting the filter inside.

    See how long they last but I don't expect anything near the advertised 10,000 hours.
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