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halogen efficiency

Discussion in 'Lighting' started by Alex Coleman, Aug 7, 2006.

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  1. Alex Coleman

    Alex Coleman Guest

    I am using four or five CFLs (a mixture of 11W, 15W and 20W) as room
    lighting plus an 18W tubular rather than halogen. It may seem odd but
    it is an ad-hoc arrangement to replace my too-warm 300W halogen
    floodlight which I used to use! says that typical efficencies
    are roughly:

    CFLs = 20 to 55 lumens/watt
    Tubular fluorescent = 60 to 100 lumens/watt

    Is the 15 to 25 lumens/watt figure it gives for tungsten-halogen for low
    voltage or mains voltage bulbs (which is 230v here in the UK)?

    Does such a lumens/watt efficiency figure for low-voltage halogen
    include typical power losses in the step-down transformer?
  2. The low end of your ranges seem too low, unless you are
    including some very small lamps.
    These must be for low voltage halogen, as 230-volt lamps
    with ratings of 100 watts and less usually are less than 15
    lm/W as far as I know. (Someone from the Europe will have a
    more definitive answer.)
    Usually not. Unfortunately, lamp efficacy for all types of
    lamps typically does not include the
    ballast/driver/transformer losses.

    Vic Roberts
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  3. On one of GE's IR reflecting ones, 225W = 5000 lumens, which
    is 22 lumens/watt. I don't have a standard halogen, but if I
    assume this is same light output as a standard 300W halogen
    (as the packet claims), then that would be 16.7 lumens/watt.
    unless it's integral in the bulb.

  4. Vic, you comment that "the low end of (the fluorescent) range might be
    too low". Unfortunately, you are incorrect. Consider the "specialty"
    phosphors, for example F40DSGN50. This is a full wattage F40 with 2200
    initial lumens for an LPW of 55.

    Jeff Waymouth
  5. With what life expectancy and wattage constraints is 26.4 lm/w the
    ultimate overall luminous efficacy of low voltage halogen?
    I suspect you are implicitly excluding photographic and projection and
    similarly specialized lamps - I know of 32 lm/w there among low voltage
    halogens - although with life expectancy impractically short for
    illuminating my living room!

    Well, yes 26.4 does look good compared to 120V ones 500 watts or less
    and with life expectancy at least 2,000 hours and excluding the HIR
    ones getting at most about 21 or 22 lm/w (as far as I know). Lower
    voltage ones do better with some "economies of scale" that favor thicker
    filament wire.

    - Don Klipstein ()
  6. Hi Don,

    I've had excellent luck with Osram Sylvania's 37-watt MR16 IRC which
    is rated for 4,000 hours service. High efficiency, long life,
    consistent product quality and a very competitve price (I pay the
    equivalent of $6.50 US per bulb, in single quantities).

    Philips has a 45-watt MR16 IR lamp that produces up to 1180 lumens
    (26.2 lumens/watt); it has a rated life of 5,000 hours.


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