Over-claimed efficiency of CFL energy saving light bulbs

I have just used a photographic exposure meter to compare the light output of a CFL bulb with various pearl light bulbs.
The CFL is a 20W bulb claimed to be equivalent to a 100W bulb. It has had about 1 year of evening use. Its measured light output is a little LESS than a 60W 2000h pearl bulb rated at 555 lumerns, and ~40% of a 100W 2000hr bulb. Power ratio for the same light output is thus 1/3 not 1/5. This is a 66% over claim in this case.
The small print on the CFL package says it is equivalent to a 1000h "soft colour" bulb. This is presumably much lower efficiency than normal pearl bulbs. This claim is therefore presumably accurate but misleading.
Having replaced several 100W pearl light bulbs with "100W" CFLs, we have reverted to pearl in all but one room.
These misleading claims must be understood and ruled out. CFLs are not yet ready to replace conventional bulbs. The calculated efficiency gains are greatly exaggerated.
Please copy to naive environmentalists, band-wagon jumpers, and government ministers.
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gmw wrote:

I've carped about this for years. The claimed outputs are nowhere near 5 times the rated wattage. When Which? did a test on CFLs I wrote to them pointing this out and asking if they could rate bulbs by their actual output, not their claimed one.
My pleas fell on deaf ears. Hope you have better luck than me in getting someone to listen.
Tim
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Tim Downie wrote:

Totally agree that light for light CFL bulbs not only are overstated but won't make a blindest bit of difference to the planet.
They do however last long enough to be cost effective. Replacement bulbs add up to a lot of money..
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The Natural Philosopher wrote:

Especially when your electricity supplier has provided them free of charge! :-))
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gmw wrote:

I would tend to agree... however if you are going to argue this, you ought to be ready for questions about how your light meter responds to the narrower spectra of CFLs Vs incandescents.
--
Cheers,

John.

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On 26 Feb 2007 03:36:31 -0800 someone who may be "gmw"

A camera light meter. Not quite the right thing to measure the output of light bulbs, though it will give some indication.
What sort of CFL were you measuring with the camera meter? Some designs take a while to achieve full brightness.

I note with interest the different conditions. From what you have typed it appears that you compared the output of a one year old CFL, measured with your meter, to the claimed output of two bulbs, the age of which you don't state. Fascinating.

Where were these installed?

For what reason(s)?

Though earlier you typed that these claims were presumably accurate. Why should accurate claims be ruled out?

Incorrect. In most cases there is now a suitable energy saving bulb. The number of cases where such bulbs are not suitable has been and is being reduced.
At one time such bulbs were really only suitable for relatively large fittings with lamps that were left on for long periods. This was because of the size/weight of the bulbs, the length of time they took to reach full output and a relative lack of robustness of the starting mechanism. However, that was in the early 1980s. The engineering of energy saving bulbs has progressed a long way since then.
--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
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wrote this:-

I have tried a variety of CFLs and I now call them "3D" lamps - Dull, Dismal and Dreary.
Experiments done under laboratory conditions with excellent test gear can produce all sorts of reliable and replicable results but the human eyes vary enormously. I'm quite prepared to concede that it's my eyes at fault rather than the CFLs themselves but, for me anyway, I'll not give these wretched things house-room.
John.
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I agreed with you about 5 years ago, but have just retried CCFL. A single 24W globe replacing a 100W incandescent far outshines it, and 3x 11W bent tubes easily replace 3x 40W bulbs.
In both cases though they take some 5 minutes, (or more), to creep up to full brightness, so I can see a case for retaining incandescents where the lamp is on for only brief periods.
--
Tony Williams.

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Tony, where did you get the 24W globes from? Are they the same colour temp as normal bulbs.
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Homebase. Can't remember the price, not cheap. It was a great disappointment at first switchon but I came back to it about an hour later and it was brighter (and maybe very slightly whiter) than the 100W bulb it replaced.
The 3x 11W folded types are inside frosted glass shades and they are less successful. I don't know why.... perhaps colour temperature, maybe CFL's need matching shades.
--
Tony Williams.

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David Thanks for your input.
wrote:

The light meter was a Gossen Sixtar hand held CdS meter, used in incident light mode. As you say, it gives some indication. To check that my results were not too wildly out, I also made an extinction photometer that I placed between pairs of bulbs, which gives similar results.

The CFL is a Philips B22 BC 15000h 1200 lumen 140mA 230-240V order code 544742xx Our mains voltage is 230V nominal, during the test I measured 228V on a basic DMM early evening. The afternoon voltage is 232V. The voltage variations obviously affect the light outputs of both types of lamp.
I took readings with the Sixtar set to 100ASA (so that EV = LV) at 5 minute intervals at the same distance of ~1.5m. At switch on from room temp the LV was ~3.0. After 5 minutes the LV was ~3.5 After 30 minutes the LV was ~3.7 A new 240V 60W 2000h pearl bulb (555 lumen) gave an EV of 3.9 and was subjectively as bright as the CFL A new 240V 100W 2000h pearl bulb (gave an EV of 4.9 and was subjectively much brighter than the CFL A new 240V 100W 1000h pearl bulb gave an EV of 5.0

The pearl bulbs were fairly new. Pearl bulb outputs are less susceptible to aging than CFLs, and pearls are statistically likely to be younger than CFLs for most of their lives, if CFLs last as long as claimed.
I think the problem could be due to supply voltages. I suspect that CFL output is more sensitive to supply voltage than pearls, in which case we need 230V rated CFLs if we are to get the claimed output.

All the bulbs were for general illumination, fitted to ceiling light fittings, mostly with open lampshades above them.

In living rooms a single "100W" CFL room light was too dim to read comfortably by etc even after fully warmed up, giving similar light to a 60W bulb. A single 100W pearl was adequate. In rooms where lights are normally off, the CFL's slow warm up and alleged reduced life caused by cycling could be a problem. CFLs would be left on much longer than pearls, negating energy saving.

The claims are no doubt accurate in the technical terms defined in the small print. Those compare the CFL light output with "soft colour" (low efficiency) type of bulb that is not used for general illumination. I suspect that they are both measured at 240V, but that CFLs may produce much less light at 230V than do pearl bulbs. Is this so? I presume that this is why the actual output of the bulbs in service is way below the "headline" equivalent output, which is why I say the claim is misleading.

I would be delighted to fit CFL bulbs that, at 230V, give similar light levels to 100W 2000h (long-life) pearl lightbulbs at the same voltage, for most of their lives, and do not suffer infant mortality or DOA.

Re lack of robustness, I recently purchased 3 CFLs (in much heavier packaging than pearl bulbs). One had broken glass, one failed quickly, the third is still going strong. Filament bulbs are much more robust. I have no financial interest except as a consumer. I want CFLs to work. They have never yet worked as advertised for me, or many others.

Giles Whittaker, Kirkliston. BAe Systems (Retired)
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I agree and have commented on this group before. Having seen lots of cfls at very reduced prices and then discovered they were not as bright as the previously used 100W pearl I went to TLC and bought a 25W CFL, having failed to find anything at Tesco, Morrisons, Wilkinsons and B&Q. Even this bulb is barely the same as a 100W and unfortunately was not the same colour temp as the cheaper CFLs or Pearl bulbs.
At least they haven't banned Pearls like they have in Australia.
If anyone can provide a link to reasonably priced CFLS of 25 or 30W I would be grateful.
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snipped-for-privacy@gmail.com wrote:

You can get 26, 32, 45, 55, 60 and 105 wat ones (mostly with ES caps) from <http://www.eurobatteries.com/sitepages/fluorescentcompact.asp . I've no idea how good they are and the higher power ones are quite pricey.
--
Mike Clarke

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Entirely illogical.

Yes, so you need to pick a higher power bulb than the packaging says. None too challenging.

which does not have the same chracteristics as the human eye.
Also CFLs do not have the same light distribution as filaments, due to their different shape.

no wonder. Try a decent one.

which is not a standard GLS bulb.

why not put a higher power CFL in?

Unlikely
only if you choose to negate them by leaving them on all the time... which would be an odd thing to do.

they already are.

A perfect description of your post.

advertising is usually bs, thats nothing new. You seem to be confusing the hype with the bulb, and reaching illogical conclusions.
NT
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On 26 Feb 2007 10:56:25 -0800, snipped-for-privacy@care2.com wrote:

I've tried a number of CFLs, so far they have all been rubbish. They start off poor and become worse fairly rapidly. They may well last for years as the makers claim but the light output will fall off in a way that does not occur with incandescent lights.
I have several 9-14W CFLs. I would say that each does exactly what it says on the tin. A 9W CFL produced about 9W of output, and that's NBG.
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Hi
Does it look like a typical CFL with folded tube?
I've had best results with Philips Softone CFLs which look more like a normal light bulb.
The 'stick' CFLs might be a bit directional too.
I now use a mix of CFL and a few well placed low wattage halogens.
cheers, Pete.
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Simply illogical.

Yes, so you need to pick a higher power bulb than the packaging says. None too challenging.

which does not have the same chracteristics as the human eye.
Also CFLs do not have the same light distribution as filaments, due to their different shape.

no wonder. Try a decent one.

which is not a standard GLS bulb.

why not put a higher power CFL in?

Unlikely
only if you choose to negate them by leaving them on all the time... which would be an odd thing to do.

they already are.

no comment!

advertising is usually bs, thats nothing new. You seem to be confusing the hype with the bulb, and reaching illogical conclusions.
NT
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gmw wrote:

In reality incandescents tend to be affected far more by supply voltage fluctuations that CFLs
--
Cheers,

John.

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Thanks John.
That makes sense to me. I was looking for possible excuses for the disparity between the maker's claims and my measurements, but it would make the disparity between the claimed and actual performance comparison between filament bulbs & CFLs @ 240V even worse.
I have just logged a complaint with the Advertising Standards Authority.
I seem to have stirred up a hornets nest with my first ever posting.
I will try higher powered CFLs, if I can find them. The best I could find the last time I looked at B&Q etc is 20W / "100W". I agree that they would save my electricity bills. However I suspect that they would also increase the much worse pollution in by China more than is saved in the UK. At least we in the UK have the benefit of nuclear power (for the moment...) (whose pollution is containable by good engineering) and of wind power (occasionally, when the wind blows strongly enough at the right time, which is not as often as the hype would have us believe).
Still, who am I to spoil the party. There is a lot of money to be made, rearranging the deckchairs on the green bandwagon. Some of it MIGHT do more good than harm. (ducks for cover) Regards.
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On Mon, 26 Feb 2007 13:08:59 +0000, David Hansen wrote:

No, he's correct. However to the hair shirt and sackcloth brigade no doubd sitting in gloom gives them a feeling that they are "saving the planet".
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