Frugal lighting

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C. Massey wrote:

That's because the rods of the eye are more sensative to blue light and the human eye has more rods than cones.
--
Ron


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Ron Peterson wrote:

or maybe even to 4100K can happen, but is unlikely.
They buy several cases of bulbs from the same supplier that they have always dealt with, almost always buying the same bulb every time. The bulbs do dim with age, and may be down to 50% of initial light output just before failure. At 5-6 years of age on the lamps, on 12 or more hours a day 5-7 days a week, light output may be down to 60-70% of initial output.
So replacing Cool White lamps with new Cool White lamps WILL provide a noticeable difference in overall lighting levels when a large area of them that are 5-6 years old are replaced.
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You wrote:

ALL lighting dims with use! It is called "Lamp Lumen Depreciation" (LLD) by the pros and can be found in the detailed specifications from the manufacturers. Mostly in fluorescents the electrode loses some tungsten (those black ends, just like incandescents) and there is some mercury loss as well. Both degrade the starting and the arc, THAT causes less light.
Electronics is a whole other issue. As is dirt on the bulb and fixture.
It is useful to note that LLD is not related to when a lamp fails. This is why some folks claim bulbs that have lasted extreme times, the efficiency has gone to ****.
Other things to note: 1. All lamps should have a "lumen" rating on the package. This is the actual amount of light as measured by more advanced technology than eyeballing a dirty piece of paper.. It should also have the expected life, in hours. Multiply the two. This is how much light you are buying for the price of the bulb and the power.
Formula is as follows: (Lumens (adjusted for LLD if you want get detailed) x Life) / (Watts x Life x $) = true efficiency (lumens per dollar). Note that you have to get your units right. Power is usually sold in KWH = 1000 watts for one hour or one watt for 1000 hours. Also the lamp life is an average statistic so it applies over large numbers of bulbs. ;-)
2. There are many kinds of incandescent bulbs. Soft White - IF - Clear - colored - 130V -120V - "long life" - halogen - shatter resistant - vibration resistant.... ALL have different light output.
3. CF's come in even more types and will vary widely by brand, model, color, lot and even within a lot.
4. Heat, especially inside a fixture, can dramatically change a fluorescent lamps efficiency. (Both too much and too little are problems.) This is why CF's upside down in recessed fixtures tend to fail quickly.
5. CF's are a softer, more diffuse light that will not be reflected inside a fixture the same way as an incandescent will.
Richard Reid, LC Luminous Views Lighting Design for Home and Business
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But perhaps no more accurately. I've seen Bunsen photometers in modern physics labs, mounted on optical benches, and so on.
Nick
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Problem with your Bunsen photometer, Nick, is that it only compares a very narrow cone of light from each source. Needless to say, CF's come in all shapes. The light emitted in one particular direction of one tube shape is *not* the end all total story.
To make a better measurement, you would need to roll/pitch/yaw the test bulb in all sorts of positions to measure the output in each direction. Or build a test box with the interior surface lined with photometers.
Just comparing a typical incandescent (more or less globular) output with a CF with a different shape is subject to these sorts of errors.
daestrom
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I suppose this problem diminishes with distance. A white paper reflector behind each bulb might help.
Nick
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Yes, they do, in fact their lifetime is based not on loss of functionality, but on reaching some percentage of nominal output.

No, that would make relative efficiency _drop_ over time.
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He might have been inept but his name has lasted longer than many who were ept :-)
How many of his critics' inventions are still used?

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snipped-for-privacy@ece.villanova.edu wrote:

Many Thanks!
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How did you measure 42.4cm from the bulb, or is that like R 3 aluminum foil..........
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I lined up the center of each bulb on the 0 and 80 cm marks on a Craftsman 939675 8m/26' measuring tape, then moved the paper along the tape until the grease spot disappeared at 42.4 cm.
Nick
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snipped-for-privacy@ece.villanova.edu wrote:

Tut writes:
Nick, if you replace one of the lamps with a burning candle, you can calculate the strength of the each lamp in candles vs lamp wattage.
E=C/d^2--------> C1/d1^2/d2^2 where: E=foot-candles C1= one candle C2= candles of light source d1= distance to oil drop for burning candle d2= distance to oil drop of lamp under test
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snipped-for-privacy@ece.villanova.edu says...

I almost read that as meaning "the grease spot" that was left on the floor where Robert Bunsen was standing at the moment of the lab explosion.
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Yeah, I've got some of those 100W equivalent, $8.97 bulbs, with a 9-year guarantee too.
I don't need a grease-spot photometer to tell me they don't put out as much light as a 100W bulb. My own eyes can tell me that. It takes a 150W equivalent to be a 100W equivalent, IMO.
The one in the hallway went out after about a year and a half to two years. I don't know where my receipt is, so I guess I'm out a few bucks.
These CFL's sure are frugal. Just make sure you send in any rebates and keep track of your receipts and the packing material for the next 9 years.
Don
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It worked out to 79%, but still an energy bargain.

Maybe not. These bulbs have a phone number (800) 378-6998 and a date code V# xxxxx printed on the base. I called the number and gave them the code and they sent me a new one, after one died.
Nick
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I think that too.

We pencil the installed date and the supplier on the item itself. We've only twice had to return them and they've been replaced with no receipt and no question.
Customer goodwill is important to stores. The items are cheap and it's recognised that some will fail.
Mary
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It's worth a try. I'll just take it back next trip to the 'depot. Thanks
Don
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On 14 Jul 2006 08:40:24 -0400, snipped-for-privacy@ece.villanova.edu wrote:

Excellent experiment.
Have you ever done a long term cost analysis on CF vs. incandescent? Does the increased cost and short life of CF's negate the improved efficiency?
Thanks!
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Bob
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wrote:

What short lives? I've been writing the install date on my CFs from the beginning and have been keeping a log. Average life is about 4.5 years. The best one, a low wattage lamp in my bathroom that burns 24/7 is still going at 9+ years.
When I can buy a pack of 5 from Sam's for $9, only a bit more than an equivalent incandescent, the enconomics become a no-brainer.
John
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I use Sylvania and GE, and sometimes they go out within a month. I do have 1 good CF that must be 7-8 years old, but most don't last a year.
What brands could you recommend that last longer than Sylvania and GE?
--
Bob

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