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    • #30404
      Anonymous

        I've recently discovered LED GU10 bulbs, which as far as I can tell are the best possible option for low energy lighting. They can be used with standard downlight fittings, come in either 12v or 240v, and use between 0.7w per bulb to 4w per bulb, depending on the make. I've tried them, expecting them to be far too weak to light most spaces, but to my surprise found them more than adequate, and even if using a few together, they're still going to consume less than a standard low-energy bulb.

        Questions:

        Are there any drawbacks I'm not aware of?

        Does anyone know of a good supplier? All the suppliers I can find either have a limited range, or don't give information on the exact wattage of different models.

        Why is there such a difference in consumption between different makes? Is it simply the number of LEDs in the cluster?

      • #32514
        Anonymous

          Our downstairs bog has 2 GU10 halogens so I'm going to buy two of these just to see what kind of light they produce:

          https://sslrelay.com/www.led-lightbulbs.co.uk/sess/utn;jsessionid=1542a6d2e247dda/shopdata/index.shopscript

        • #32515
          Anonymous

            I've tried a couple of standard white ones, 0.7w, which seem to be available from all mainstream electrical trade suppliers such as C.E.F. It is quite a cold white light, not too bad for a space like a hallway or stairwell, but not friendly enough for a room. I've ordered a yellow one to see if that works in combination with the cold white, (yellow, red, blue and green are also available from most suppliers), and I've also ordered a warm white, which I found on this site, though it's hard to tell from their garbled 'specification sheet' what it's wattage is –

            https://sslrelay.com/www.led-lightbulbs.co.uk/sess/utn;jsessionid=1542a610259c85f/shopdata/index.shopscript

          • #32516
            Anonymous

              Agree about their spec sheets I spent quite a while trying to decipher them yesterday.

            • #32517
              Anonymous

                Put them in on Friday, I reckon we've got at least a 30% reduction in light levels and the light is much colder than the halogens. Plus you've also got 48 visible light bulbs within the lamp. I think the tech needs to move on a bit.

              • #32518
                Anonymous

                  I've tried the warm white, and it's good, one lamp is perfectly adequate for the stairwell I needed to light. I'ts a 4w consumption, so nowhere near as efficient as some of the others, but still not bad.

                  The most efficient ones I've found are from a Chinese company called Landlite. Their lamps are 0.7w each. They have a website – http://www.landlite.com – but it has no details of retailers. Worth asking electrical suppliers if they can get hold of them. If anyone starts producing a warm white that's down in the below 1w range, then I think it could really take off.

                  In terms of replacing existing halogens, it's only worthwhile on mains voltage systems. With a 12v system, the transformer will draw the same amount of power no matter what lamps are attached to it. Though if specifying for new projects, there are 12v LED kits available which come with a dedicated low wattage transformer. The advantage of 12v systems is supposed to be clearer focused lights and longer lasting bulbs. Does anyone know if that would still apply when using LED's?

                • #32519

                  From what I've read in the near future (10 yrs?) LEDs are unlikely to reach more than half the efficacy which T5 fluorescent tubes have achieved since 1995 (T5s provide about 100 lumens per watt). I agree that the light quality might improve.

                  T5s can be used in domestic lighting schemes if one knows how to use indirect lighting and efficient reflectors to conceal the light source. (e.g., this has been done in the USA).

                  Also there are some compact fluorescent lamps (only a few kinds) which can achieve an output of 70-80 lumens/watt – also well ahead of today's LEDs.

                  The predictions of the future could turn out to be totally wrong, but there are theoretical limits to the efficacy of light sources and the best fluorescents are getting relatively near to it. On that basis I dont hold out too much hope of LEDs beating fluorescents, although they might eventually equal it (and be useful when small sparkling lights are needed).

                  David.

                • #32520
                  Nick Grant
                  Participant

                    I was hoping someone who knew would put record straight on efficiency, thanks David.

                    However efficiency is not just measurable in lumens per Watt but Jobs done per Watt and as you suggest LEDs could have a useful role for accent lighting where a very small focussed beam will do and to replace the ridiculous number of low voltage halogens which most people seem to believe are low energy (voltage = energy!).

                    So replace the 20 halogen spot downlights in the ceiling with fluorescent but consider LEDs for creative ways to add atmosphere or minimum light levels without adding Watts?

                    Don't know if anyone has seen the corridoor lighting in Point Hotel Edinburgh but they use a few vertical coloured fluorescent tubes, quite low power but the result is dramatic rather than dull and 'low energy' although lumens per m2 are low. Immediate reaction is 'wow cool'. T5s in efficient reflective fittings would have looked terrible at the same Watts per corridoor.

                    Here endeth the eco-minimalism sermon on something I know bog all about….

                  • #32521
                    Anonymous

                      Nick, sounds great I will try to source some around here (Bristol) & report back, Mike.

                    • #32522

                      If you only want small amounts of light, 5, 7, 9 & 11 W CFLs (the ones without loads of parallel tubes) are very efficient for the size esp. if run off electronic ballasts (another few W). More light for less electricity than LEDs for at least another decade – that's my forecast. How many lumens do you get from a 4W LED?

                    • #32523
                      Anonymous

                        the only thing I don't like about fluorescennts is the quality/colour of light they produce. LED's still got a long way to go though.

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