Do modern compact fluorescent bulbs waste energy if you often turn them on an off?

Question

With traditional tube fluorescent bulbs, my understanding is that there is quite a bit of energy required to get them started. For instance, in a public restroom, the lights are typically turned on and off repeatedly during the day, so it might apply that an incandescent bulb would be better .... or leave the fluorescent bulb on.

Do compact fluorescent bulbs share this characteristic?

Is it a true or flawed guideline to use compact fluorescent bulbs mostly in situations where you will be leaving the light on for some relatively extended amount of time? If so, what is the "break-even point" where a compact fluorescent bulb is preferred?

Note: perhaps my impression about tubular fluorescent bulbs is obsolete and they have gotten better.

Answer 1

If you are comparing turning a compact fluorescent lamp on and off as needed with simple leaving it on, the fraction of time it is OFF determines if energy is wasted. A good compact fluorescent lamp is about 6-7 times more efficient than a standard incandescent lamp, so that a 10 watt CF produces about the same illumination (measured in "lumens") as does a 60 watt incandescent. When first turned on the CF must be heated near its ends so that an electrical arc can be started. This uses extra energy that does not generate useful light. The amount of energy is 3-4 times what the lamp uses when normally illuminated and the starting period varies with the initial temperature, but is usually no longer than several seconds. So, if the desired OFF period is measured in minutes or more, energy would be saved by turning it OFF.
However, there is more to cost than energy usage. A CF normally has a long service life, as great as 10,000 hours (compared to 1000-2000 hrs for an incandescent lamp). But this 10,000 hours is for a lamp that is not turned off. The starting process shortens the life so that a CF lamp that is turned ON and OFF every few minutes will have a much shorter service life (this is also true of an incandescent lamp). Since CFs are relatively expensive to replace, the lowest total operating cost would be obtained by not turning it OFF for periods under 30 minutes or so.

Answer 2

The old rule of thumb was to turn an incandescent light off if you were going to be out of the room for a minute, and turn a fluorescent off if you were going to be gone for an hour. The new compact fluorescents are better than the traditional tubes, but not that much better, so I'd stick with the old rule of thumb for the time being.

Fluorescents, new or old, contain a bit of mercury. Perhaps we should not rush headlong into their general use.

Answer 3

for them to work they have to build up a charge to promote one of the electrons to a higher shell on the atom and then be free to carry the current (the by product of which is the light)
conventional are just resistors that resist the current flow and yell you guessed it (the by product of which is the light and often heat)

so the answer is yes but with modern technology the gap will shorten so It really depends on which bulb you use and what time spell your talking

I hope this sorta helps

Answer 4

The stuff about "don't turn off a fluorescent because it uses too much power to start" is wrong.

Think about it. If the fluorescent used 100 times as much power to start for a whole second (not possible, you'd blow a fuse or trip a circuit breaker) you'd still be better turning it off if the time it was off was as little as 2 minutes.

What used to be true was that starting a fluorescent frequently made it likely you'd burn it out. I don't think that's true any more.

The same is true for PCs, air conditioners, heating systems, etc. In spite of myths to the contrary. When you're not using something turn it off. When you're not home set the air conditioning to a higher temperature or the heat to a lower temperature with a programmable thermostat. Set the heat down at night when you're under covers. All that saves energy.

Answer 5

there is an episode of mythbusters that will tell you all about this.

Answer 6

The compact fluorescent was 25% of what an incandescence light that produces the same amount of light. I am a Senior citizen and need to cut back in the bills to stretch my retirement. I don't believe in Global warming .