This site has some MR16 warm white LEDs - they look interesting -
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have not tried leds for home lighting yet because until recently they were not really able to compete on light output, light quality and cost. Now they could be worth considering as they would save power, run cooler and last far longer than normal bulbs or fluorescents - they may also be useful for lighting in enclosed spaces where halogens would overheat. The downside is if they should fail early for any reason, then you lose all your expected energy savings in the cost of replacements.
The CFL looks better using standard fittings, rather than halogen style spot and basically matches the LED for total cost of ownership, although the LED may still be better on environmental grounds due to lower energy usage, but then semiconductors are a dirty business, so may lose their advantage on that score.
At the absolute best, using mixed colour LEDs, appropriately picked, LEDs may put out a little under half the light of fluorescant lights. (watt for watt) 'White' ones, at best, get about a third, more typically a fifth.
White LEDs are about as efficient as halogen bulbs.
Led lights last a long time and are quite a bit more expensive. However their light is also very directional so if you wanted a wide beam they would be no good for you.
I noticed a year or so ago that the new buses round here were using clusters of LEDs for their tail/brake/indicator lights, very good I thought.
But I have noticed over the past few months that about 1/3 of the individual LEDs have already blown, seems these ultra bright LEDs are being pushed too hard, negating the reliability (and corresponding lack of required maintenance) which was presumably a major factor used to justify their use? I assume the reduced power consumption compared to filament lamps is a relatively minor factor given that the alternator is sucking it's power from the dirty great diesel lump on a bus?
I don't think I've ever seen properly driven LEDs "burn out" anywhere else, of course the ones from Birkett's I play^H^H^H^Hexperimented with years ago without using current limiting resistors were a different matter!
They've made an appearance as filming lights, and others report that they are no better than fluorescent types designed for a similar job (soft source) in terms of battery life.
They are, of course, directional. Wonder if the figures you've given include a reflector for the florries to match that?
I use LEDs and standard halogen bulbs for caving and I can assure you that the halogen bulb wins on light output. I suspect that if you had enough LEDs to match the output of a bulb then there would be precious little difference in consumption. I only use the LEDs as emergency backup lighting.
I 'spect you're right about them being overdriven. There's still a win over single blubs as far as relamping goes, since (as you've observed) individual LEDs can lose their holy smoke while the rest of the cluster still gives out useful photons...
I tried 12 LED lamps and they were attrocious, in theory replacements for halogen spots but a complete waste of time. Light was very poor and had a blue'ish tinge making it look very cold.
there are floor mounted LEDs in the building i work in that were installed about a year ago. A fair proportion of the leds in each unit seem to have failed so i'd back that up.
They're also being used a lot for Cycling lights. I had one of a set of about 10 fail in one light but thats' it. However - usage in that situation is maybe a few hundred hours a year tops which is nothing really.
The latest generation of front lights use a single ultra bright white LED. They probably have a lot more potential and are supposedly giving out the equivalent of a 20watt halogen but are still expensive. The technology is moving fast so expect to see these in a while.
efficiency claims are rather unclear - they're claiming it's a
5watt LED that gives equivalent light to a 32 watt halogen. Then go on to say that they're only twice as efficient as halogen. Now 5 watts is 5 watts which suggests that they're a)heavily overvolting it or b) the electronics that drive it are very inefficient and another
10watts is soaked up there.
Which are now actually available. This field has moved on incredibly in the nearly 4 years since this post.
A good 'warm white' high power LED will now put out comparable amounts of light per watt as a CFL, and if you're willing to accept really nasty colour rendition, it can rise to nearly as efficient as a linear fluorescant. (60lm/w, 100lm/w).
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