LED Lighting

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18 posts

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#674953 21-Aug-2012 09:18

Lets assume we want the efficiency from a 3000K light (assume the led die temp is 85 deg C)

Here are the incorrect ways (but most common) in order of how wrong it is.

- 1000 lumen / 10 watts = 100 L/watt (it will say on box "for 5000k led")
- 850 lumen / 10 watts = 85 L/watt
- 1000 lumen / 13 watts = 77 L/watt (it will say on box "for 5000k led")
- 850 lumen / 13 watts = 65 L/watt

(To stay competitive we have also had to published efficiencies based on the above)

The correct way is as follows:

(750 x .9 x .91) /13 = 47L/watt

The best way is to have the light output measured by a integrating sphere to calculate the output lumen.

In practise it is not easy to make a focused dimming light with an efficiency over 60 - 65 L/watt

timmmay

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#674962 21-Aug-2012 09:24

switchlighting:
The correct way is as follows:

(750 x .9 x .91) /13 = 47L/watt

Assuming 750 is lumens you have two magic numbers in there... what are .9 and .91, and where did you get them from?

switchlighting

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#674967 21-Aug-2012 09:31

lens loss = 0.1 so multiply by 0.9
Glass loss = 0.09 so multiply by 0.91

These are approximate real life losses.

CYaBro

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#674974 21-Aug-2012 09:43

timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.
It also doesn't say what brand of LED they have in them.

Opinions are my own and not the views of my employer.

timmmay

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#674979 21-Aug-2012 09:46

CYaBro:
timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.

Not dimmable, apparently the dimmable model is out soon.

The driver's not inside the light, there's a cord between them. I doubt you can replace it if it breaks, but honestly at $80 the lights are so cheap that if they fail after 5 years I just replace the whole unit.

CYaBro

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#674985 21-Aug-2012 09:47

timmmay:
CYaBro:
timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.

Not dimmable, apparently the dimmable model is out soon.

The driver's not inside the light, there's a cord between them. I doubt you can replace it if it breaks, but honestly at $80 the lights are so cheap that if they fail after 5 years I just replace the whole unit.

g

Bugger! Your link is working now and the price is only $67.90 at the moment. :D

Opinions are my own and not the views of my employer.

richms

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#675037 21-Aug-2012 11:38

CYaBro:

Bugger! Your link is working now and the price is only $67.90 at the moment. :D

I can only find 3000k on lighting direct. At that price if they do 4000k or better then it becomes a no brainer to install them, so long as the beam spread is acceptable for in home use.

Richard rich.ms

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Skolink

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#675058 21-Aug-2012 12:24

switchlighting, will the new EECA / Energy Star luminaire labelling standards address the inconsistancies with claimed light output and efficiencies. All I am aware of is the CFLs will now have to be labelled with light output (in lumens).

timmmay

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#675062 21-Aug-2012 12:29

richms:
CYaBro:

Bugger! Your link is working now and the price is only $67.90 at the moment. :D

I can only find 3000k on lighting direct. At that price if they do 4000k or better then it becomes a no brainer to install them, so long as the beam spread is acceptable for in home use.

I can't remember what I got, and they're not installed yet. From memory I got one that's neither a cool white nor a warm white, a nice balance.

It has a beam spread of around 90 degrees, with a translucent diffuser, so it's pretty good. I had one working in my hand, it's really pretty bright.

richms

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#675065 21-Aug-2012 12:32

Ok, will be interesting to see how they go.

I am very happy with the 7w viribrights in normal downlights around the house so would only be considering these for the bath areas, would want the same colour as the rest of the house.

If the price approches the price of a viribright in a cheapish recessed E27 GLS fitting then I might opt for them in other places too, but really I think just kitchen and bathroom need the IP fittings.

Richard rich.ms

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#675474 22-Aug-2012 13:36

Lights arrived this morning.
Just wired one up temporarily on the workbench at work and almost blinded myself!
Not a good idea to be looking directly at the LED when you turn it on. :)

Opinions are my own and not the views of my employer.

timmmay

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#675477 22-Aug-2012 13:45

I had the same experience with my LEDs, super bright... just like any light bulb really.

richms

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#675491 22-Aug-2012 14:22

Ive just got my 10W bare LEDs on a heatsink from ebay that I am going to be putting in the aquarium, cant recall if I got the 10000k or 12000k now, but till my drivers arrive I cant really see how they go.

Richard rich.ms

switchlighting

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#675808 23-Aug-2012 09:21

Hello Skolink,

Interesting question.... Only lights that pass the rigorous energy star testing will have to display any of the energy star required markings. I have had a quick look through the energy star tests and packaging but cannot find a requirement to mark with lumen output.... not sayings it not their though as the document is 40 pages long. I would imagine if it is energy star then it should be correct though.

Cheers.

networkn

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#678854 29-Aug-2012 17:16

Do you think it would be reasonable to use LED lighting in a kitchen?

http://www.houzz.com/photos/kitchen-lighting-and-cabinet-lighting/

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