Twice as much.
"Every CFL light contains a small ac-dc power supply with reactive
components in it that will affect the CFL's power factor (PF) - that is, the
load presented to the ac line. The closer the PF is to 1, the better. A load
with low power factor (<.85) draws more current and is less efficient than a
load with a high power factor for the same amount of useful power. ... These
power losses don't show up directly on our electricity bill, but the
utilities sure see the effects.
"I put one of my home CFL bulbs on my Kill-O-Watt power meter recently and
measured its power factor: It was .57. This is lousy. "
With the usual low power factor electronic-ballasted CFLs, most of the
"non-real" portion of the current is neither inductive nor capacitive, but
in the form of harmonics.
- Don Klipstein ( firstname.lastname@example.org)
One reservation we have about the use of CFLs is that since we heat
most homes here with electricity (hydro generated) anyway and never
need, in this climate AC, the so-called wasted heat from cheap (25
cent) incandescents (when on at night for example) is merely an
alternative to our electric heating!
One place that CFLs do make sense is outside, where they are sometimes
left on at night for safety and insurance reasons. But CFLs in very
cold climates do not seem to be always the best choice and ot you have
to buy expensive ones to get good starting and colour!
Also CFLs do not seem to be a good or necessary choice for locations
where they are flipped on for a short time, such as stairs, cupboards
etc. they supposed to be used (like strip fluorescents) where they
will be left on continuously.
We have a bunch of those, with electronic ballasts, (from a school
renovation) in our workshop.
Interesting finding; what about switching power supplies also?
It is true that the old incandescent bulbs do provide heat, however,
like resistance heat, they are very inefficient. IIRC a good heat pump
will provide about four to six times as much heat as a resistance heater
or incandescent for the same power consumption.
EJ in NJ
While I'm not going to say lighting is the ideal way to heat, and
there's truth to the heat pump, it achieves such efficiencies only when
source temperatures are relatively high whereas the resistance heater is
the same irregardless.
I think what you meant to say is that using electricty only** is a
very expensive way to make heat. That doesn't meant that incandescent
light bulbs are an inefficient way to provide heat. I believe that
they are 100% efficient, in that all the electric power that is used
is converted to heat and light, and the light is converted to heat
when it lands on a surface (except for the light that that gets out
through a window.)
Light is absorbed by a black surface and converted to heat at that
time. Light is partially reflected from a white surface, so part of
the energy is converted and part is reflected. You can tell that not
all of the light is reflected because if it were, when the light
source is turned off in an all white room, there would still be light
inside the room, when in fact it goes dark almost instantaneusly.
**As opposed to using electricity to power a heat pump or an oil
That's because the heat pump brings heat from the outside to the
inside, and the electricity just powers the process. An electric
powered coal stoker, that brought coal from a coal pile to a coal
furnace would generate even more heat per KWHour, although I don't
know that people would call a coal stoker an even more efficient means
of heating. Although maybe they would.
On Apr 9, 7:36 pm, email@example.com wrote:
You can look at an incandescent bulb as being something like 99%
efficient compared to an ideal resistive heater, meaning that 99% (and
I'm pulling that number out of the air) of the electricity that passes
through the bulb is eventually converted to heat. Some of it is
initially radiated as visible light, but most of that is eventually
absorbed by some surface and converted to heat (sort of). I think the
only real loss is any visible light that goes out through a window,
But he's comparing it to a heat pump which, rather than converting the
electricity into heat, is using the electricity to move (pump)
existing heat from outside the building to inside. Basically, an air
conditioner in reverse. Supposedly, under the right conditions, this
can bring in more heat than what would be produced by converting 100%
of the electricity it uses directly into heat.
I personally know nothing about how much more or under what conditions.
Duh... Now that I think about it, I'm sure the reason a heat pump can
be so efficient is because if the compressor is inside, most of the
electricity it uses is also converted to heat inside the house on top
of what it brings in from the outside...
And of course, you're wrong. As someone explained very well earlier,
a heat pump is efficient because it's MOVING heat, rather than
generating it. Modern heat pumps can generate more heat for the same
Kwh than resistance heaters, even when the outside temp drop into the
teens. BTW, the compresors in the ones I've seen are outside.
On Apr 10, 8:32 am, firstname.lastname@example.org wrote:
I understand what they do, and I said I knew nothing about how
efficient they were at doing it (for the sake of argument, not taking
anyone's word as correct on that). My point was that even if one
happened to be very inefficient at moving heat, it would be, at worst,
atill be functioning as a pretty good radiant heater (as does almost
anything else that uses electricity).
The heat pump is OUTSIDE. You'd have to stand there to get any
radiant heat from it. And anything that uses electricity is NOT
necessarily a pretty good radiant heater or even a radiant heater at
all. The common electric water heater being one good example, which
heats via conduction.
On Apr 10, 8:25 pm, email@example.com wrote:
My mistake, but ideally if you were using the heat pump for heating
only, you could make the system more efficient by putting the pump
inside. Probably too much of a noise issue for most people though.
An electric water heater heats the water by induction, but when the
water is not being used most of that heat eventually radiates out into
the home. It's not an effective radiant heater, but still an efficient
one when you're not carrying that heat away for other uses.
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