Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



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.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.
Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
 Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.

The AECB accepts no responsibility or liability for any errors or omissions in the content of this site. Views given in posts are not necessarily the views of the AECB.



General: How long from the LED lab to the shops?

Bottom of Page

1 to 30 of 58

  1. <
  2. 1
  3. 2
  4. >
    • CommentAuthoraa44
    • CommentTimeSep 13th 2009
     
    Does anybody know how long it takes on average for a lighting product to move from the lab to the shops?

    I am currently planning my new house and I am keen to fit LED lights. Most of the LEDs that I can find on sale produce about 40 lumens per watt (lm/w) so, to get the equivalent of, say, a 35 watt halogen downlighter that produces about 525 lumens, you meed about 13 watts of LED. Given that most LED lamps on sale seem to be 4-5 watts, this means that I'm either going to have a very dim kitchen or I am going to have a ceiling full of lights.

    I have read reports / press releases recently saying that both Philips and Cree have LEDs in their labs that are producing well over 100 lumens per watt. At that sort of output, LEDs start to become viable alternatives to existing downlighters.

    What I am wondering is whether anybody has an educated opinion on when we will start to see these LEDs for sale?

    Thanks
    AA
    • CommentAuthorwookey
    • CommentTimeSep 14th 2009
     
    The question isn't so much time from lab to shops as time from supply to incorporation in lighting products. 80 l/W LEDs from Cree/Seoul semiconductor and Limileds have been on sale for over 2 years. 90l/W ones from lumlieds for a year or so. Seoul P4s (80l/W) are over 2 years old and I've been using them for that long in my caving and bike lights. The thing is that these LEDs are relatively expensive and lighting manufacturers tend to use older and cheaper devices in their bulbs and fittings. You also need to bear in the mind the 10-15% losses in the conversion from mains to the low voltage used to drive LEDs.

    I too would like to use LEDs in the house, but a) find that much of the time manufacturers don't even tell you the LED efficiency and when they do it's usually no better than CFL. Look out for anything that specifies Seoul P4, Cree MC-E, Luxeon Rebel for efficiencies >75 l/W (before any transformers).

    An interesting option is Seoul acriche LEDs which run directly off the mains (lots of LED chips in series). I still haven't seen anyone putting these in actual luminaires.
    • CommentAuthorPaul_B
    • CommentTimeSep 14th 2009
     
    I'd also add Nichia. Currently Ultraleds have a GU10 fitting producing 440 lumens from 5W (88w/l) and the angle of beam is also good at 120 degrees. However, they are 21mm longer than a normal GU10 and they certainly aren't cheap at £34.99ea

    I bought the predecessor to this which was 4W, 350 lumen and must admit it is the best LED I have seen for birightness and colour.

    Paul
    • CommentAuthorCWatters
    • CommentTimeSep 15th 2009
     
    £30-£40 seems to be about the current price for LED lamps producing around 500-600 Lumens (eg equivalent to 35W halogen). Most aren't standard GU10 form factor.

    Brighter fittings exist..

    Thorn Base LED downlights claim 650 Lumens.

    These claim to produce 750 Lumens which is half way between 35W halogen (600L) and 50W (900L) but cost £65 each (16 off).
    http://www.litewave.co.uk/10w_led_downlighters.asp

    These produce 1400 Lumens but I've not checked the price. They appear to be mainly for offices and have 0-10V dimming.
    http://www.artandsciencecombined.com/Products.aspx

    Not tested either myself.
    • CommentAuthorwookey
    • CommentTimeSep 16th 2009
     
    GU10 & MR16 are a terrible form-factor for LED lamps. They are designed for halogen bulbs which like to be hot. For LED longevity and efficiency they need to be as cool as possible. Even the best ones are still putting out just as much energy as heat as as light and good designs move that away as much as possible. It's very hard to get the heat out of a GU10 or MR16 fitting (which is why the good ones are finned).

    We really need to get away from these form factors for LED lighting in the medium term. They are useful as an interim measure but it's poor engineering. Good luninaires should take forms like LEDs mounted on aluminium channel. e.g. something like this stuff: http://www.litewave.co.uk/high_power_led_tape.asp mounted on aluminium heat sink. That tape appears to be 50lumens/watt (doesn't say exactly which LEDs are being used).
  6.  
    I have just tried out a 3w gu10 led from my local electrical wholesalers. I was very surprised by how much light it gave out and my electrican was impressed. That model has now been upgraded to 5w and I will be installing them in my renovation. I have been quoted £14.50+vat which seems like a great price compared to what I can find on the internet.

    http://www.gaplighting.com/Website_catalogue.pdf
    • CommentAuthorPaul_B
    • CommentTimeSep 16th 2009
     
    • CommentAuthoraa44
    • CommentTimeSep 18th 2009
     
    Thanks for all the replies. Things seem to be moving in the right direction. I'm probably about a year from having to make any choices so things will no doubt have moved further by then. I think that Wookey is right in that LEDs give the opportunity for lighting manufacturers to come up with some very innovative and effective new designs and I look forward to seeing what they come up with.
    • CommentAuthorRobinB
    • CommentTimeSep 19th 2009
     
    See also CWatters thread " New type of light bulb. Not LED or CFL..."
    • CommentAuthorCWatters
    • CommentTimeSep 19th 2009 edited
     
    Elsewhere someone has pointed me to a new EEC regulation designed to allow LEDs to be compared to incandescent lamps...

    http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2009:076:0003:0016:EN:PDF

    The important bit seems to be Table 6 below. This sets the rules for how many lumens an LED must produce if it claims to be "equivalent" to a certain wattage of incandescent lamp. Nice idea but sadly if you rely on that "equivalence" you might be slightly dissapointed...

    Modern 50W halogen down lights produce around 800-950 Lumens but the regs appear to allow the LED manufacturers to claim that a 638 lumen LED is equivalent. So if you want to buy an LED downlight that's as bright as your existing 50W halogen you may need to buy one that claims to be equivalent to a 65-70W halogen downlight. Clear ? :-)
    • CommentAuthorwookey
    • CommentTimeSep 20th 2009
     
    I don't see where you are getting your numbers from cwatters?

    My reading of thst table says that to claim '60W bulb' equivalance, a halogen has to emit 702 lumens, an LED 806 lumens. That doesn't look like an unfair adantage to LEDs to me. There is also mention (in table 3) of dividing by1.1 for LEDs requiring an external power supply (presumably to allow for PSU losses). Not clear if that is additional to table6 or not, without a more careful reading.
    • CommentAuthorCWatters
    • CommentTimeSep 21st 2009
     
    Oops, Yes looks like I missread the table.

    They will be able to compare an LED GU10 downlight to an ordinary incandescent GU10 rather than a halogen GU10.
    • CommentAuthorRobinB
    • CommentTimeSep 21st 2009
     
    I notice lots of the LED lights are running at 12v.

    Might it be worth adding an extra lighting circuit (to the house we're building) for them with a view to powering it from PV-fed 12v batteries? I particularly like the LED tape as I prefer to see light to light fittings and the source can be hidden.

    Useful table CWatters, thanks!
    • CommentAuthorPaul_B
    • CommentTimeSep 21st 2009
     
    Its a question that has been asked before. You need to consider the current you are drawing as this dictates the thickness of the cable. In practice you'd need fairly thick cable to send a 12V ring around the house to ensure it can handle the current and minimise loses due to distance.
    • CommentAuthorCWatters
    • CommentTimeSep 21st 2009
     
    Perhaps an example would help on that point...

    Suppose you have a kitchen with 9 off 5W LED downlights. That's 45W or about 4Amp. That doesn't sound too bad and many people would incorrectly use 1.5 mm^2 cable normally used for mains lighting. However suppose your kitchen is 20 meters away from your battery. The resistance of 1.5mm^2 cable is about 0.013 Ohms per meter and 40 x 0.013 = 0.5 Ohms. The voltage loss would be 0.5 x 4 = 2 Volts so your LEDs would see 10V rather than 12V. The wire would also dissipate 8 Watts as heat so you'd be wasting around 17% of the electricity your solar panels collected.

    It's also worth noting that the installation of 12V lighting (LED or otherwise) is notifiable under the Building Regulations unless the lights are part of a pre-wired set (eg with plugs and sockets already fitted).
    • CommentAuthorRobinB
    • CommentTimeSep 22nd 2009
     
    As you've probably guessed I know very little about this - is it that you're better off bringing down the voltage close to point of use? At least I'm put off the idea of 12V ring!
    thanks for your helpful posts
    • CommentAuthorwookey
    • CommentTimeSep 22nd 2009
     
    Well in general it is 'clearly' a good idea to have one large efficient converter from mains to low voltage, then attach all the lights to that 'LV main', because each little cheapo converter from mains to 12V is only about 80% efficient.

    However, as cwatters points out, voltage drop losses in cables can be quite significant if the cables are not very short so it's easy to still lose 20% (and have dingier lights than designed).

    So yes, if it was me I'd try hard to power a lot of lights from one (or two) central step-downs, but often a step-down in the room in question is just as good from an efficiency point of view. It wqould help a lot if sellers were _required_ to publish efficiency information on their kit - then you could actually make an informed comparison (they actually vary from about 65-95% efficiency).

    Moslty the way to maximise efficiency is buy efficient kit.
    • CommentAuthorPaul_B
    • CommentTimeSep 22nd 2009
     
    In addition it would be useful if LED drivers sold by LED retailers had higher rated output. Most seem to top out at around 15W.
    • CommentAuthorRobinB
    • CommentTimeSep 22nd 2009
     
    Wookey, How long is a short cable please? 1m, 5, 10, 50? I just really don't know.
    thanks!
  20.  
    Hi aa44,

    How many sets you want for your kitchen, maybe you can tell me how big the kitchen is, and how many lumens you want. I can get it for you from my supplier in China.
    • CommentAuthoraa44
    • CommentTimeSep 23rd 2009
     
    Hi agson. Thanks for the offer but I'm not ready to buy anything yet! The architect doesn't even start 'til next month.
    AA
    • CommentAuthorwookey
    • CommentTimeSep 24th 2009
     
    RobinB. That's a 'how long is a piece of string' question. See Cwatters example sums. The fatter the wire the longer the cable can be before excessive voltage drop. Or alterantively - the longer the wire the fatter it needs to be. I suppose for a rule of thumb I'd guess anything under 5m will be OK. More than that and I'd do some sums.
    • CommentAuthorListysDad
    • CommentTimeSep 24th 2009
     
    Something to consider about LED lamps folks.
    The life of them is oft quoted as effectively 'forever' 150,000 hrs etc. Whilst they do indeed continue to function for a very long time, you will find that output falls off pretty sharply pretty quickly - especially when they are 'over driven' to produce those few extra lumens to start with.
    So, your once spangly eyeball stingingly bright lamps will eventually have you reaching for your wee williy winky candle holder if you don't change 'em very regularly.
    • CommentAuthorCWatters
    • CommentTimeSep 24th 2009
     
    Good point. The lifetime should really be specified as the point at which the light falls to 80% (?) of it's original specification.
    • CommentAuthorPaul_B
    • CommentTimeSep 24th 2009
     
    Never experienced light level fall-off for any of the LED lights I have now or in the past. The same can not be said for CFL

    Paul
    • CommentAuthorListysDad
    • CommentTimeSep 24th 2009
     
    Paul B Did you measure to start off with? Fact is its a very gradual deterioration and only really noticable when you install new alongside 'old'. Remember our eyes are awesome bits of kit compensating for all manner of things without telling us till it's really bad! BUMP - bugger! Time for new glasses...:crazy:
    • CommentAuthorwookey
    • CommentTimeSep 25th 2009
     
    Lumen degredation rate depends primarily on LED temperature - which is why the fitting/mounting design matters so much. LEDs run at relatively low currents and temps will keep 90-95% of their lumen output all the way out to 100,000 hours. Leds run at highter currents and temps won't. http://www.philipslumileds.com/pdfs/WP12.pdf gives good details and shows that a K2 power LED at 1.5A (i.e full blast) and 115C will fall to 50% output after 80,000 hrs. One run at same current and 135C will be at 50% after about 20,000hrs. So as you can see, junction temp really matters. On the other hand there will be less than 10% loss before 10,000 hours in either case.
  28.  
    Hi everyone,

    Great info thanks - much more to LEDs than some claim!!!

    I was under the impression that an advantage of LEDs was you reduced the in ceiling heat issues - especially on the loft ceiling with all the insullation we now put on top of the lights!! How much heat is produced by LEDs compared to other light forms such as halogen???? Have building regs caught up with LEDs??

    Thanks...
    • CommentAuthorCWatters
    • CommentTimeSep 25th 2009
     
    Posted By: AberborthinHi everyone,

    Great info thanks - much more to LEDs than some claim!!!

    I was under the impression that an advantage of LEDs was you reduced the in ceiling heat issues - especially on the loft ceiling with all the insullation we now put on top of the lights!! How much heat is produced by LEDs compared to other light forms such as halogen???? Have building regs caught up with LEDs??

    Thanks...


    LEDs produce far far less heat than halogen - but they are less tollerant of the heat they do produce.
    • CommentAuthorwookey
    • CommentTimeOct 1st 2009
     
    Halogens turn about 90% of their energy into heat. The best LEDs only turn about 50% of their energy into heat. (from memory, but that's right ballpark) (conventional incadescent bulbs turn about 95% of thier energy into heat).

1 to 30 of 58

  1. <
  2. 1
  3. 2
  4. >
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press