CFL vs Incandescent

Given, CFL's are thought to be more energy efficient than incandescent bulbs. But I heard they use more energy to turn on.

What if it is in a room that is used infrequently, a closet or guest room for instance. In other words a room in which you would go in and out of pretty quickly.

How long would a CFL have to be left on to realize the net energy savings.

thanks for your input, bonnie

Reply to
bonnie
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Mythbusters did a segment on that. The break-even point was something like 6/10ths of a second.

The better question is, is this really a question considering that you aren't going to be able to buy incandescent lights next year.

Reply to
Pat

There is no Thought on if cfls are more efficent, they are in fact

75-80 % more. Replace them first where you save the most.
Reply to
ransley

The turn-on energy difference is miniscule, but each start removes about

6 minutes (0.1 hours) from a CF's typical 6000 hour lifetime at a typical $2 cost, vs a bulb's typical 750 hour lifetime at a typical 50 cent cost.

You might better ask "How long would the CFL have to be left on per start to save money over an incandescent bulb, with 1/4 the power consumption, at 10 cents/kWh?"

Nick

Reply to
nicksanspam

That is absolutely false. It is a continuation of an old myth that fluorescents have some big surge in power consumption when they are turned on, supposedly amounting to a significant amount of energy consumption. That is simply not true.

That is a mistranslation from advice to leave fluorescents on rather than turn them off and back on, unless they will be off for a substantial amount of time - due to starting-related-wear.

This varies widely with lamp wattage, lamp cost, starting technology used, and your electricity cost rate. I would say, as a "one-size-fits-all" figure that is at best a ballpark, 5 minutes for wattages at least 10 watts.

I consider closets, refrigerators and motion sensor lights to not be candidates for CFLs.

There are cold cathode ones that do not experience starting-related wear. However, they cost more, are less widely available, available only in lower wattages mainly 8 watts and less, are less efficient than the usual hot cathode ones, and still need to warm up to achieve full light output. Cold cathode CFLs are best for frequent on-off use. They take too long to achieve payback when they are off 98-99% of the time.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

The ban does not kick in until 2012, and only affects general service ones of a certain range of brightness. Even then, ones that achieve some higher efficiency standard are exempt. I got just an hour ago a couple that I believe will get around that ban by using "halogen infrared" technology.

These are Philips Halogena Energy Saver. I got them from Home Depot. They look like ordinary soft white incandescents, of the squarish shape used by some Philips lightbulbs in North America (and Westinghouse before they sold their lamp division to Philips).

There is a 70 watt one with light output fully on par with a 1500 hour (double life) soft white 100 watt incandescent, and a 40 watt one with light output fully on par with a 60 watt 1500 hour soft white incandescent. Both of these are rated to last 3,000 hours and are rated to be fully dimmable.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

Look at your question this way, you have an incandescent in a spare room that you energize for a total of 60 minutes per year. If it is a 100 watt bulb and you pay 15 cents per kilowatt hour, you use 1 1/2 cents worth of electricity per year. Not much of a savings to be had.

OTOH if you have a bulb you burn for 6-8 hours per day, CFL wins hands down.

Reply to
Roger Shoaf

On 4/27/2008 2:11 PM bonnie spake thus:

The initial inrush (or surge, if you prefer) current that you're talking about is pretty small. Leave the CFL on a minute and any energy cost from turning it on is negligible.

Reply to
David Nebenzahl

I remember one college project was to figure out how long you needed to turn out a standard the old 4 foot tubes before you would save money. Factoring in the cost of electricity lamps and the labor for maintenance to replace them, it turned out to be about 20 minutes. We had a fun statistics class back 35 years ago. The CF's would be far less. That start up surge is like 1/30 of a second and is about 10 times or less of the rated lamp consumption.

Reply to
Joseph Meehan

Hmmm, For start up normal ilament lamps creates surge current at the moment it's on. Most any electrical load being inductive will do same.

Reply to
Tony Hwang

If you hardly ever turn them on, they'll never pay for themselves.

Reply to
CJT

I remember doing calculations on 4-footers of 32-40 watt range also.

One more thing: There are older figures going around as to life lost per start that date back to 1970's-1950's, and/or are based on "glow switch" starters (which typically blink the lamp a few times before getting it on to stay on). 4-footers since the early 1970's at least have mostly not needed glow switch starters, due to use of ballasts that have starting means.

It appears to me now that a 4-footer can gain savings by being turned off for as little as a minute in comparison to being left on. It appears to me that this explains why I have seen a few instances of motion sensor switches to turn off the lights in rooms illuminated by 4-footers if nobody is there - even in a government building restroom!

As for CFLs - they cost more than 4-footers and consume less power than

4-footers, as well as not being as durable as 4-footers! Therefore CFLs often are better being left on rather than being turned off and back on 5 maybe 10 minutes later, while 4-footers are more in the category of turn 'em off when you leave the room!

As for effects of labor costs - I still see it being worth turning off

4-footers if they will probably stay off for at least 3 minutes, and CFLs if they will stay off at least 10-36 minutes or so (depending on CFL type and wattage, electricity cost rate, and labor cost).

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

I should have made it clear that those numbers were based on the available technology of the time and that today's technology is very different.

I can remember about the same time I was working at a very large discount store about the same time when the manager decided to replace all the lamps at the same time. The difference as amazing. It was sun glass time. It was one of the very few good things he every did. Lucky for me I worked for a lease department so I did not answer to him.

Reply to
Joseph Meehan

never use spray polish anywhere near a CF.

I did a little of the mist must of entered the base vent holes, lamp has wood.

anyhow the ballast part erupted in a flame......

i now spray the rag and wipe the wood area.....

i was exciting:(

Reply to
hallerb

We have many recessed floods on dimmers. Dimmable CFL's are WAY too expensive right now. I sure hope that changes before anyt kind of ban on them.

And I hope something improves with the "warmup" time. I now have all CFL floods in my kitchen. When I'm ready to make dinner, I have to pre-heat the lights and the oven at the same time. :)

Reply to
Mitch

ed text -

The inductance of a filament type bulb is negligible and doesn't cause any surge. In fact, with an inductor the effect is exactly the opposite. The faster the rise time of the incoming voltage waveform, the higher the impedance, which restricts current flow.

The current being higher at start up is only due to the fact that the filament resistance is lower when cold than when it's at operating temperature.

Reply to
trader4

On Mon 28 Apr 2008 05:53:02a, told us...

Mitch, the CFL floods I have in my kitchen take 5-7 seconds to reach full brightness.

Reply to
Wayne Boatwright

What are you doing here? :-)

Mine take about 3-4 minutes! I have various brands (10 lights total), and they all take that long.

What kind do you use? I want those!

Reply to
Mitch

Yours must just be very old. I have lots of kinds and brands, and they all come up to full strength in less than 10 seconds. The only one that takes minutes is a bulb in a closet that's been there for more than 5 years.

Reply to
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