What type of functions do LED lights perform in home lighting systems? For which parts of the home are they best suited to?
Congrats to madzedong, first post in this category!
+ Among the major strong points of LED lightbulbs is very low power usage, even compared to compact fluorescent lights (CFL). So they would be good for lights that are almost constantly left running, such as night security lighting.
+ Also, LEDs don't seem to have a problem with being frequently cycled on and off. The usable life of a CFL is greatly reduced by turning it on and off. So LEDs might be useful in high-traffic areas of a building like a bathroom where the lights are constantly turned on and off.
+ In theory, the usable life of an LED lightbulb should be much longer than anything else. But in practice... we'll see.
- Among the frequent complaints about LED lightbulbs is lack of flood. So they might be more useful for spotlighting or vanity lighting near display cases and the like. However, newer models seem to be getting around this limitation.
- Much higher price for LED lightbulbs. Let's hope they last as long as they claim.
- In general, the current gen LED lightbulbs are rather dim compared to a CFL or traditional incandescent.
All great points Mr. Admin. We are likely on the verge of an LED pricing breakthrough for quality replacement incandescent lighting. Several cost effective prototypes have already been developed but have not yet been slated for production. For now, nothing is as cost effective as compact florescent lighting (CFL) for efficient typical indoor lighting solutions. My take is to hold off on indoor LED lighting technology unless you have a specific (and usually very expensive) need. If you must buy LED, stay away from the cheap Chinese stuff. There are overwhelming reports that bulbs often do not make it past the first month before they fail... pure junk.
If you havent looked into CFL's recently, you might be amazed at the low cost, high lumen output per watt and the many sizes and styles that are now available. 95% of my entire home is CFL, including outdoor area lighting and indoor chandeliers and spotlights. I get a tax break when I buy them and they come with a standard 5 year guarantee from some of the largest name brand lighting manufacturers.
If you enjoy creating your own lighting projects, here's a small primer that might get you started.
Of course you also assume full liability for your own creations.
This is really designing out loud - I have one light at the apex of an L-shaped corridor which pretty much has to be lit when the house is occupied if I want to be able to close any doors at all. At the moment it has a wildly inadequate 20W CFL in it as I can no longer buy 250W (4000 lumen) incandescent bulbs. I did make one of these hamster ball fixtures but owing to a stupid wiring mistake and 80 year old cloth insulated wiring I nearly caused a fire. And did weld a lightswitch open.
Big Clive's site is a fun read.
XM-L's are the first LEDs to beat good CFLs in lumens/watt. But that means driving them at fairly moderate currents to get the efficiency. A 100W bulb is about 1750 lumens - that's about $20 of XM-L's and a suitable power supply. Which is not going to be free.
The LEDs will be at rated output/efficiency at up to 85 Centigrade which ought to be feasible - but will require careful thermal design. The top end of the linear efficiency curve is at around 1500mA - above that, efficiency drops though output rises. At 1500mA a U2 bin XM-L is pushing about 600 lumens so we need three and a half of them to replace out 100W bulb. Driving at 1500mA will simplify the thermal management at least. Keeping the junction temperature to 85C or less means keeping the package temperature to something like 60C or less. This will not be a problem for any fixture designed for incandescent bulbs as they will tolerate far higher temperatures.
So for my application I'm going to want 5 or so XM'Ls driven gently, so I'm going to need something like a 15V 1.5A PSU. It is probably simplest to drive them as a string of 5 in series.
Buying one of these is going to cost as much as or more than the LEDs for something that won't burn my house down. I can actually exploit the directionality of the LEDs to my advantage though - I might be able to get away with 4 of them. But this fitment is already costing me around $60 - and I have to add good heatsinking and hide the thing in a sensibly sized light fixture. The 20W CFLs cost me about $2 and last about a year. This means the XM-L solution has to last till I'm well over 80 to make sense on purchase costs of hardware. And that is putting no value at all on my time. So I'm now using something around 15W instead of the 20 or so from a CFL. But am getting more light than before. Let's say better than a 30W CFL. So its running costs are half as much. Say it is lit for 8 hours a day, 250 days of the year, or about 2000 hours a year. No CFL I've had has lasted more than two years but at $2 a pop this is no big deal. My hypothetical fixture will use 2000x15=30kWh a year. The CFL fixture will use twice as much. Assuming I manage to cool my hypothetical fixture adequately I should get 40-50000 hours out of it - let's call it 60000 so I get 30 years out of it. I need 30 years for the capital costs to equalise.
At 30 years I'll have used 900kWh for the LED fixture and 1800kWh for the CFL fixture. A kilowatt-hour costs me 12 pence (about 20 US cents) but the price is going to rise by about 15% in the next year and will multiply by several times over the hypothetical lifespan of the fixture I'm thinking about building. At today's prices I'll have spent around $60 on CFLs and around $350 on electricity. Or $60 on an LED fixture and $175 on electricity. But the capital is up-front and if they crack fusion in the next three decades, electricity will probably rise more slowly in price.
If I bill my hourly rate for design and fabrication against the amount of time it would take me to head to the nearest supermarket 15 times in 30 years, LEDs do not yet remotely make sense for such an application.
But one day I hope they will.
I think Id avoid the hamster ball in future lighting projects. Its good to hear that the wiring didnt fail inside a wall and burn your house down.
Have you tried CFL spotlighting yet?
I have one of these mounted on one side of my garage ceiling to illuminate the car engine bays and toolboxes. All three heads can swing in any direction. You could get something similar with 2 heads and point one head down each coridor. I use 3 x 23W CFL spots. They provide a pleasing neutral glow and put out an amazing amount of light. Or you could use the same unit as mine and point one straight down at the apex with a 13W CFL spot and aim the other two down each end with 23W CFL spots. They also work well as reflective lighting and you could point them at your ceiling to diffuse the beam and adjust the aim to get them perfectly to your liking. The beams actually have quite a wide diffuse angle and dont provide any annoying hotspot.
If you must LED, have you selected your host yet? If you can get some larger thick copper plumbing pipe and conceal it behind a glass fixture, then you've got the heat sink portion covered. You could even use a rubber mallet or vice to squeeze the pipe into an oval if more space is needed. Then fujik your stars to the pipe in the usual manner. As for a power supply, do you have any computer recycling companies close by? Id go with a name brand laptop power supply (no chinese dx type junk on this project) since it needs to be completely safe and reliable. Assemble your LED fixture, grab your DMM, alligator clip wire jumpers and some plated paper clips and bring them along with you so you can test which power supply provides what you are looking for. Use the data plate on the supply only as a basis, not as the gospel for what the actual measured output will be. I have noted during my LED lamp conversion that several completely identical power supplies did not provide nearly the same output, especially while direct driving an LED. Once you've found what you like, leave the supply plugged in for an hour before you buy it to see how warm it gets. A quality properly rated supply will get warm but not hot and are designed to sustain a rated load with a 100% duty cycle.
No computer recycling companies? There's always ebay for used power supplies but then you wouldnt be able to load-test them with your particular setup.
IMO, CFL's still sound a lot easier and far more cost effective at this point in the technology time line.
Stupid question, but one that needs to be addressed if we are to do this right. E27=standard US screw-in light fixture?
Perhaps someone should write up a guide on the various terminology in regards to house lighting.
Not a stupid question at all. Its all as clear as mud but this might help:
yes sir E27 is standard regular bulb
Wow! thanks for the replies guys! Means a lot for a newbie on this forum. :D
Since LED lights are dimmer than CFL, they may not be recommended for the Kitchen, for example, where a clear view on things is necessary?
This made the knowledge more accessible to a wider audience.
Even though the last two posts appear to be spam, I thought I'd mention the 1.3W LED "bulbs" I got from Wal-Mart. About $8 I think.
As I recall the frosted one is rated for 69 lumens, and the clear, 72 lumens. So, they are pretty dim, but I put 5 of them in my house anyway. 2 are in lamps in the kid's room, so I don't have to yell at them for wasting electricity when they leave the light on all day/night. The kids have managed to break off both of the outer glass enclosures so they are not very durable (not that anything glass is going to be durable around kids), but the LEDs inside continue to work. 2 more are in desk lamps, and the last one is in a reading lamp. All work fine for their intended purpose, reading or typing. I wouldn't try to illuminate a room or hallway though, not even a closet.
The clear version has a mottled "beam pattern" casting light and dark areas, so the frosted flavor is probably what you want unless you're putting it in a lamp with a shade.
The emitters themselves appear to be a cluster of standard 5mm through-hole LEDs, but with a "slow phosphor" to eliminate 60Hz flicker (there is an afterglow effect when switching the bulb off). Indeed, they don't flicker, except when my laser printer warms up.
As I expect these are probably cheap crappy LEDs, I imagine they will not last their full rated lifetime before dimming, but so far so good after several months. As long as they last long enough to pay for themselves, I think I'll be happy. In the case of the kid's room, they're probably already close to break-even. ;)
Tsk, tsk. Pretending to be a customer of your own shop is a big lie....
ok so this may be an old thread but as i have converted my entire home to run led light bulbs i would certanly recommend these
i have a 4 bar gu10 strip in my kitchen that used to run 50w halogens these have now been replaced with 3x2w dimmable led's imho these are actualy brighter
these have been running without a problem for over 6 months now before i was swapping out a halogen bulb at the rate of one every 2-3 months for the same price these cost me
i aslo have two light fittings in my living room with these bulbs in each with 3 bulbs
2 fittings in my hall one top one bottom with 3x1watt gu10
and one of each fitting with the same 3x1w's for the bedroom but i used warm white in these i have had to relpace 2 of these but the leds still work the driver is the weak point there
in the bathroom i used blue leds
got the light fitting as a job lot and fleabay cost me £20 for 10 light fittings plus postage
the 3x1w were about £3 each the 3x2w dimmable slightly more expensive at £7 plus postage
i have also converted a freinds house over to these after he saw mine
the price of high power led is dropping fast, now you can buy a 100w led for 12$(ofc chinese with low CRI) in 5 years we will convert the fluorescent/halogen lamps in led
$12? a very very cheap price, i am not sure if it is of good quality? any quality warranty?
I think there is an updated answer to the question of this old thread. At this moment almost every type of light bulb in a house can be replaced by an equally or better performing led bulb. The market is quite overcrowded with cheap meh-performing trash led bulbs, but if you are able to ignore that there are are really good performing led bulbs from the established brands (Philips, Cree, Sylvania). The only area that is not covered well as far as I know is the replacement of 4000K halogen bulbs, high CRI 4000K leds are available (we all know the Nichia 219 92CRI) but I have not seen a high output householt bulb with them.
marked as SPAMMER
djozz doesn't seem like that spamming type, hahaha.
Back on topic,
Bought several of these from FT to replace halogen downlights in my home.
Will get back to you guys on how they perform.