Are CFL More Efficient Than Normal Tube Lights?

You are confusing me with jargon. Will I save power, if I replace my living room tube light with a CFL for equal illumination ?

What are the wattages of the tube in place today and the proposed substitution?

No....it's the same thing....plus you will have to change the fixture.....

You got the engineers answer, you would have gotten the right answer had you stated your "real" question up front.

If you're only interested in light output and not how it's distributed then go with the CFL, generally less wasted energy in the ballast but it does vary by the brand.

Why do you have tube lights in your living room, do you live in a converted garage or something?

I doubt you will save money in this application, especially if you have to replace all your fittings.

You are confusing me with jargon.

Sorry, but please remember the CR4 posting rules, you need to clearly explain your questions so we can tailor our answers to your needs. This is an Engineering forum after all and some us used to work for NASA for example and so you may get an answer you don't understand if you don't explain your question in enough detail.

it is confusing but Ram is correct. if you read the package your cfl will say something like..."same amount of light as 100 watts" while consuming less energy as a fluorescent.

A "normal" tubular lamp can use a high-efficiency reflector (a mirror-like polished aluminum sheet) to reflect most of the light flux which would otherwise be absorbed by the fixture. In the case of a CFL, about half the light is trapped inside by the coiled or bent tube. It will come out eventually (after being reflected at least once by the lamp surface itself, a poor reflector). Can it have as high an efficiency as a tubular lamp?

Generally speaking, CFL and 'normal' tubular fluorescent lamps have the same efficiency. The actual term is 'efficacy': lumens per watt; both type of lamps produce roughly the same number of lumens for a given wattage used.

A factor almost as important is the reflectivity of the surfaces of the walls in the room. There is a 'power factor' involved in determining the useable brightness of a lamp. If room A is painted with an 80% reflectance gray paint and room B is painted with a 92% reflectance white paint, then room B will be nominally brighter by a ratio of (.92/.80)³ = 1.52, or about 50% brighter (not just 12% brighter). This is a rule of thumb I've used as an optics engineer.

Yea, as a fellow Illumination Engineer I am sure that helped clear that up for anilsaxena.

Your answer is most down to earth among all. That watt per lumen efficiency of a CFL is no better than that of a Tube light. This is what I exactly wanted to know. Rest depends upon shape, ballast efficiency, room's properties etc. I may extend it by saying, that even transportation cost of a CFL from factory to shop shelf is cheaper. This brings a further question. How many more years it will take, before GLS lamps vanish (in true tradition of VCR, floppy disc, compact audio cassette etc.) and give way to LED lamps. In my house now I have four LED lamps, and reduction in the electricity bill shows their presence.

CFL is more better than incandescent bulbs.

LED is more better than CFL.

The sun is the best and cheapest, followed by candles.

Candles suck....plus they start fires...

But, the sun doesn't work at night.

Sure it does. Here's the core of Sun at night as seen through the Earth in the 'light' of neutrinos. Let's see a CFL beat this for illumination (of course you have look down through the floor to see it. And squint real hard )

But the candles make all those nasty air pollutants in your house. Electric lights, even battery powered are better. That way the pollutants aren't at your place, they are left for someone else to worry about them down at the power generating plant, unless it is hydroelectric generation. Let the other guy worry about them!

Yes, the sun is the best especially with gallons of Coppertone available.

Good Luck, Old Salt

I totally agree about the Sun but, man, it sure sucks having to run 860 MPH at my latitude carrying all that Coppertone just to keep up with it!

check the lux level of LFL and replace it by a CFL of same lux level and see whether brightness is same or less or improved.Also check cost of bulb & fitting including accessories as well as wattage and cost of replacement for a given period,say.15years.

For LFL power consumed is more than that written on the lamp due to control gear losses,does the same apply to CFL,if so how much?.

Is the definition of efficiency of a light means lumens/watts input or incuding losses in lamp & controlgear,is pf not taken into account?.

Mr.Anil Saxenaji,

From to-marrow power bills will increase by 7% in New Delhi . Better to avail all power saving devices.

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What language is "audience"

Must be the same as audience.

We got the ones made in China and crap they supplied 50hz for 60hz supply. Crap it doesn't last very long. I guess that's far more than efficiency.

can depend how you are billed. The little fellas 11W etc have appalling power factors. In theory Watts (power) = Volts x amps. In AC circuits you need to involve power factor. A good power factor would be around 0.95 for a light with electronic ballast. Look to the little CPL and you will find (all be it not published) that the power factor is closer 0.5. so the real energy used is twice what it claims on the box. 22W lamp would take 44VA.

Now if your bills assume a pf then no problem but in a commercial situation not so clever. Generally the the new range of tubes are more efficient - 65W compared against 58W with little difference in lumen output.

As others have said you also need to look to the control gear. Switchstart wastes more power than electronic.

Its a minefield with 'green' information spread by many misinformed all be it good intentioned people.

"misinformed all be it good intentioned people." I believe your statement to be correct. But I wonder about our Congress. Why did it cost Phillips over the reported 2 million per senator to get them to pass the bill?

Interesting discussion.

I never checked efficiency differences but according to my own experience both at home and in the industry, CFL are way less reliable than traditional FL tubes of good quality used with very good electronic HF ballasts. Those ballasts allows a higher lighting efficiency and improve the useful life of the tube. I don't have numbers but the difference is there. Of course I'm not referring to cheap crap electronic ballasts. So, overall, FL is finally less expensive than CFL because within the same time you change the CFL several times.

As other mentioned it the PFC is also better with the HF ballasts, not surprising that CFL electronics are crappy, they must cost close to nothing. All CFL I've seen had to be replaced due to failed electronics, not tube end-of-life. Forbidding incandescent for common use was sort of stupid as is some cases CFL is overkill.

No, they are the exact same technology.

Light intensity (brightness) is measured in lumens.

Read the small print and be aware that in most cases the new efficiency ratings on CFL/fluorescent is accomplished by lowering the lumen output. (Less power in = less power out when using the same technology and results in dimmer lit areas.)

Note that due to environmental regulations the quantity of mercury in CFL/fluorescent lamps has been severely reduced resulting in reduced lamp life.

To maintain the same lumens in any lighting application while reducing power consumption requires use of LED or new Induction type lighting.

When choosing the lighting be sure to pay careful attention to the color rating number: 2K, 3K, 4K with 4K being closer to white sunlight.

Doing some research on lighting efficiency verses cost on the internet will yield a great amount of useful information.

Nah - wrong.

Shocking the old phosphors might be the same technology but the smaller dia tubes are more efficient.

4ft white 36W 2850 lumens 79.2 lumens/watt

4ft white 40W 2800 lumens or 70 lumens/watt

Not all efficiecies are the same though.

In fluorescent lighting, the ionised mercury is driven to a higher energy state by electron flow through the plasma. When the ions jump down to a lower energy state, they give off photons which can be reabsorbed in the plasma. So the smaller the diameter, the less the distance a photon has to travel to excite the powder coating.

That is what makes them a little bit more efficient. But you are not likely to see a difference on you bill at home. Where I work it costs about 1 penny for every hour of operation of a ceiling fixture with four T12-34 watt energy saver lamps. Three T8's can provide more lumen's than the four T12's. Justification to upgrade requires a 2 year payback (by our policy) or a 24% ROI at a minimum. Makes it tough to justify.

As others have stated, it is about lumen's (or candle power if you want to do the conversion).

From all the discussion, I conclude that CFL are no or marginally better in the matter of lumen per watt output. Therefore changing to LED lamps makes sense. In my house, I am replacing every fused CFL with LED lamp. A good unbranded chinese 15 watt LED can be bought for about $1.5 (the same with Philips or OSRAM brand costs more than $10, perhaps made by same manufacturer in China for Philips or Osram - so much so for greed of these dying companies). I am satisfied with them with a noticeable reduction in my electricity bills.

Did you compare the pf,harmonics & harmful radiation ,if any, from the three brands?.