CFL Analysis – Power Factor

CFL Power Factor may vary from below 0.5 to over 0.9 depending on type of integrated ballasts (traditional magnetic or electronic high-frequency), and also depending on ballast manufacturer and quality of ballast.

The Lighting Research Cente: Power Quality, which includes tables & graphic illustrations of how CFLs, computers and other non-heating appliances distort power supply harmonics, explaines the difference between incandescent (incl. halogen) and fluorescent (including CFL) lamp effect on the power system:

“Incandescent lamps, toasters and other heating devices usually have a power factor of unity = 1. (…) Resistive loads such as incandescent lamps actually reduce voltage harmonics.”

“Poor power quality can damage the distribution system and devices operating on the system. (…) High frequency electronic ballasts operate at frequencies ranging from 20 to 60 kilohertz (kHz). The harmonics produced by these ballsts are correspondingly high frequencies and can interfere with some communication equipment including radios, intercoms, and cordless phones. Devices that use power-line carrier signals, such as synchronised clocks and control modules for building energy management systems may also experience problems if harmonics exist at frequencies close to the carrier signal.” [1]

However, according to a study at the Vienna University of Technology (cited by the Swedish Energy Agency ), distortions may vary with the actual situation and depend on the CFL in relation to other appliances and other CLFs, e.g. distortions may decrease if CFLs are of different brands, but increase if they are of the same brand. [2]

But this is not the main issue. As demonstrated on this site CFLs Real Power Used, CFLs with poor power factor may use up to twice as much power as claimed! [3]

Looking for a second opinion on this astonishing revelation, I made a few calls.

- According to a representative at Swedish Osram, an 11W CFL may in fact use around 18W! The integrated ballasts also use about 2W.

- The Swedish Energy Agency says this sounds about right. That a 15W CFL may have a PF around 0.5 and a VA of 30.

- Vattenfall, one of Europe’s biggest energy suppliers, said they are well aware of the difference between active and reactive effect and that they bill larger customers for their VA, whereas smaller customers are only billed for the active effect (= watts used). But to compensate for reactive effect from home electronics and CFLs with poor power factor, a generalised extra fee is included in the standard price per kWh! When I asked what will happen if more people start using significantly more CFLs, the reply was that utilities will have to compensate by making this extra hidden fee higher! This, of course, is nothing customers are informed about (unless one asks, and knows what to ask).

To get a Canadian EnergyStar label “an average of 10 samples tested must be greater than 0.5″ – which is not overly reassuring as it needs to be at least over 0.85 in order to not create distortions and tax the energy supply with more than the watts it is marked with.

Technical Editor Margery Conner of EDN also found confirmation of CFLs poor power factor (0.57 in her own CFL, and 0.45-0.50 in a Luminaire Testing Laboratory test) and wanted to know what EnergyStar plans to do about it:

“I emailed Peter Banwell of the EnergyStar program and asked if EnergyStar was considering making minimum PF a requirement for Energy Star compliance. He replied, ‘We looked at this in detail several years ago and decided against it, though there are a couple of utilities that still support the idea. We may take this up in the future, as the market share grows, but right now it is still in the noise in terms of impacts.’” [4]

1. Lighting Research Cente: Power Quality
2. Fyra frågor om lågenergilampor, Swedish Energy Agency, 1999.
3. CFLs Real Power Used
4. “Utilities suffer from CFL’s poor power factor”
See also “The Hidden Costs of CFLs”

Summary:
The suboptimal power factor of many CFLs on the market means that they both use more power and indirectly cost more for the customer than consumers and environmental organisations alike have been led to believe, e.g. 18W + 2W for the integrated ballast instead of claimed 11W.

Update: Found a very comprehensive e-newsletter about cinematography lighting from ScreenLight & Grip, which also goes into the power factor issue for different light sources under the chapter Lighting Load Types (along with spectral distribution, CRI, colour degradation and other fascinating subjects).

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13 Comments

  1. David said,

    May 19, 2009 at 11:48 am

    For some reason I have vague recollections of the very first CFL bulbs sold in the UK actually marking themselves in a similar fashion, i.e. claiming 15W + 3W, listing the ballast separately as it was often also sold separately.By the way, Well Done on providing such an excellent and extremely informative site.

  2. Halogenica said,

    May 20, 2009 at 2:05 pm

    Thanks! :-)

  3. Skip said,

    September 7, 2009 at 12:35 am

    I live in a cold climate, the Canadian Maritimes. During our winter season, I've noticed my exterior CFL's take a very long time to reach full brightness. I assume this start up period results in a higher energy draw than when the CFL's are operating at warmer ambient temperatures. Has any research been done to calculate this effect?

  4. Halogenica said,

    September 7, 2009 at 4:14 am

    Not that I've seen but I think you may be right about that. Are you using CFLs especially designed for cold weather? Standard CFLs work very poorly at low temperatures.

  5. John M. Morgan said,

    February 8, 2012 at 7:14 pm

    This link at Home Power indicates that the claims made here are not accurate.
    http://homepower.com/article/?file=HP96_pg128_Letters_1

    • halogenica said,

      April 1, 2012 at 10:08 am

      John, a belated thanks for the article.

      Could be that it is right or partly right (I’m a designer, not an electrician) but why then would the Swedish Energy Agency, one of the leading lamp manufacturers and leading utilitiy (all VERY active partners in the pro-CFL campaign) confirm that CFLs use more energy than their marked watts? All were of course eager to stress that even with this little power factor issue included, CFLs still use less energy compared to standard bulbs.

      They’re just not quite as effective as claimed, especially if you add the combined effect of erroneous conversion tables; light deprication over time; sensitivity to position, temperature, frequent switching etc; quality variations between models and brands; heat replacement effect and (unbiased) life cycle analyses.

      But all these issues are still not the main problem. It’s the mercury content that makes them a really, really bad alternative. Plus the visibly and measurably poorer light quality.

      • John M. Morgan said,

        April 1, 2012 at 12:27 pm

        >>. . .Swedish Energy Agency, one of the leading lamp manufacturers and leading utility . . . confirm that CFLs use more energy than their marked watts?<>It’s the mercury content that makes them a really, really bad alternative.<>visibly and measurably poorer light quality.<<

        You say you are a designer. I am a professional photographer and graphic designer and have no problem with the better CFLs, though I have mostly now switched to 5000k LEDs which I find delightful, like having daylight in my studio. I can't for the life of me understand why so many people prefer dingy, yellow incandescent bulbs to daylight.

      • John M. Morgan said,

        April 1, 2012 at 1:22 pm

        I will try reposting my message.

        “. . .Swedish Energy Agency, one of the leading lamp manufacturers and leading utility . . . confirm that CFLs use more energy than their marked watts?”

        I need to see the primary sources to know whether your statement is meaningful. Here are 2 more links about CFL power factors:

        http://open4energy.com/forum/dc/dce/real_power

        http://www.alteraeon.com/~soda/dsp/cfl-power-factor.html

        “It’s the mercury content that makes them a really, really bad alternative.”

        I trust you are equally fired up about all fluorescent lamps for the same reason, not to mention amalgam fillings in teeth which leach mercury.

        “. . . visibly and measurably poorer light quality.”

        You say you are a designer. I am a professional photographer and graphic designer and have no problem with the better CFLs, though I have mostly now switched to 5000k LEDs which I find delightful, like having daylight in my studio. I can’t for the life of me understand why so many people prefer dingy, yellow incandescent bulbs to daylight.

  6. otitismedia 67890543 said,

    April 12, 2012 at 2:33 pm

    Someone who refers to his unnamed 5000K CCT LED studio lighting as “daylight” is trying to ridicule and lecturing anyone? Simply hilarious!

    • jmrpress said,

      April 12, 2012 at 2:52 pm

      I didn’t intend to ridicule anyone, just stating my experience. The 5000k LED bulbs which are made in Taiwan by TESS and imported by Earth LED are admittedly not cheap, but I love the quality of the light.

  7. halogenica said,

    August 14, 2012 at 4:31 pm

    I missed replying to this comment again, sorry.

    “I trust you are equally fired up about all fluorescent lamps for the same reason, not to mention amalgam fillings in teeth which leach mercury.”

    Yes. I removed all my amalgam fillings 25 years ago. And I personally dislike all fluorescent type lighting and most HID lamps but as it would not be practical to have only incandescent lamps in the commercial, industrial and road illumination sectors, I accept the necessity of FL/HID until there are affordable and mercury-free replacements that give the same quality light. The difference is that in professional use, there is a very high degree of recycling due to shape and already established routines.

    This is NOT the case with lamps in the private sector, and CFLs are so small and easy to chuck in the bin, unlike long tubes. Therefore I think all mercury containing products for private use should be banned a s a p.

    “I can’t for the life of me understand why so many people prefer dingy, yellow incandescent bulbs to daylight.”

    Of course you need a much white and brighter light in a photo studio. Those are very specific work conditions with special requirements.

    For the rest of us I think daylight is fine in the daytime (preferably the real thing). At night it is not natural or good for melatonin production with bright white light.

    Preferences may also vary with culture and latitude. People living in more northern climate zones often prefer the warmer light whereas those living closer to the equator tend to like cooler light. Which seems pretty natural when you think of it, doesn’t it? Also, many women and highly sensitive people prefer a softer, warmer light, whereas many men like bright white light, especially when working. (To generalise a bit.)

    I personally feel very uncomfortable in cool-white light, unless it’s the real thing, coming from the sun. Somehow sunlight never feels that cool (except at dawn), even at its whitest and brightest.

  8. December 30, 2012 at 2:24 pm

    I create a leave a response each time I like a article on a blog or
    I have something to contribute to the discussion.
    Usually it is caused by the passion displayed in the article I looked at.
    And after this post CFL Analysis – Power Factor Greenwashing Lamps.

    I was excited enough to drop a thought ;-) I do have
    a couple of questions for you if you tend not to mind. Could
    it be simply me or do a few of these responses come across like they are left by brain dead folks? :-P And, if you are posting on other sites, I would like to follow anything new you have to post.
    Would you list all of your social pages like your Facebook page, twitter feed, or linkedin profile?

  9. halogenica said,

    January 3, 2013 at 7:29 am

    I don’t write so much on other sites and prefer to keep my facebook account for more private uses. But thanks for your interest! :)


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