Do LED Light Bulbs Save Money Compared to CFL Bulbs?
On the basis of simply comparing the electrical current used by CFL bulbs, to LED bulbs the answer to this question is that most of the time they will save you money while operating. However, I have seen comparable LED bulbs that use just as much current (electricity) as the CFL bulb and so it would not save money even while operating. Also, since the LED bulbs usually cost far more than the CFL bulbs, using LED bulbs is costing us far more rather than less.
When you add to the extra cost of the LED bulbs the fact that these bulbs have very limited warranties, we will see that buying an LED bulb which fails shortly after its warranty period ends up costing far more than the comparable CFL bulb does.
When we used to buy incandescent bulbs (the ones with the filaments in them) which would fail in, usually, less than two years, the manufacturers knew fairly well how long, on average, a bulb would last. This was because the filament was the active part, which almost always failed. Very few bulbs of this type ever failed in any other way.
Let's understand what a warranty is for and how it's calculated. First, a warranty is there to help you protect your investment, but it is calculated by the manufacturer based on how many bulbs fail and when. No manufacturer can warranty a bulb for 10 years if the vast majority of bulbs don't last for at least 11 years. So, if a bulb has a warranty of two years, we know that the vast majority of bulbs of this type will fail sometime after two years.
The incandescent bulbs were so inexpensive that I don't ever remember bothering to keep track of any bulbs to see if they did operate up to and past their warranty period. With the advent of CFL bulbs, which were costing two or three times what the incandescent bulbs cost, I started paying attention to when I put them in operation and when they failed because it seemed to me that they were failing far too soon.
As I looked into this, it turned out that they were, in fact, failing far sooner than the warranty period indicated they should. (Every CFL bulb from reputable manufacturers has been replaced under warranty.)
Recently I had my first LED bulb fail in a little less than two years, which was within the "intended" warranty period. But, since I hadn't placed the bulb into operation until two plus years after I purchased it I discovered that the warranty period had already expired. It was expired before I even started using it! This bulb ended up costing me far more to operate than a comparable CFL bulb and, when I did the calculations, it even cost me more to operate than an old standard incandescent bulb would have, assuming that one incandescent bulb would have lasted the 22 months the LED bulb lasted. (I did manage to contact the manufacturer and explained the issue. They asked for the receipt which I supplied and a photo of the bulb on which I had clearly marked the date I put the bulb into service. I have received an email saying that they would be replacing the bulb.)
There seems to be a wide gap between the LED bulb warranty and the advertising of the expected life of the LED bulb that catches most people by surprise. In very big characters most LED bulbs say they should last 20,000 or 30,000 hours. Then, in smaller letters, it says, "based on the life of the LEDs." The problem is that advertising the expected life of the bulb based on the life of the LEDs is like basing the life of an incandescent bulb based on the expected life of the glue used to cement the glass bulb into the screw base of the incandescent bulb. In the case of the incandescent bulb, we know that the failure is almost always going to be the filament, not the glue used to hold the glass bulb into the bulb base. As far as I know, all current bulb warranties are based on the expected operating of the bulb which is always stated as 3 hours per day 365 days a year, or 1095 hours/year. (I believe this was also the expected operation of incandescent bulbs as well.)
For the LED bulbs, like the CFL bulbs, there are a number of other parts within the bulb which makes it operate and probably fail before the LEDs. In CFL bulbs, there are resistors, inductors, transistors, and capacitors. One can assume that the LED bulbs are similar. (I haven't yet taken an LED bulb apart to find out what all is inside but that may happen some time soon.) -pk01
So, based on the warranty periods of the LED and CLF bulbs, will buying an LED bulb, which dies one day after the warranty period, save us money?
It turns out that if a 6W LED bulb dies after its warranty period, it will not save us money when compared to a 10W CFL bulb that lasted the same amount of time. This is because a CFL bulb only needs to last about eight months to hit the break-even point when compared to an incandescent bulb. The LED bulb needs to last far more than two years to hit that same break-even point all because of the price of the LED bulb.
What surprised me was how long the LED bulb had to last in order for it to hit the break-even point when compared to a CFL bulb. This time turned out to be about 18.9 years. Yet, an LED bulb warranty is only 2 - 5 years.
Let's look at the calculations. Basically, we want to find the point at which the cost of the LED bulb plus the cost to operate it equal the cost of the CFL bulb plus the cost to operate it.
The calculations were for 40W-equivalent LED (1.5W and 6W) and CFL (10W) bulbs.
NOTE: In all the equations that follow I will be using the standard computer math symbols:
+ is the plus sign, add
- is the minus sign, subtract
* is the multiplication sign, multiply
/ is the divide sign, divide (not used)
The ecosmart LED bulb uses 6W and claims a 22.8 year life and gives a 5-yr warranty. This is less than 20% of the "expected" life of the bulb. Using this bulb for only three hrs a day for five years is a total of 5475 hrs for a cost of (5475 * 6W == 32.85 KW * 0.10 = $3.29) for the electricity for the 5 years.
The electricity used by the CFL is 10W/6W ~ 1.67 times more or 1.67 * 3.29 = $5.48 for the five years.
The LED bulb costs $10, the CFL costs $1.67 (assuming $10 for a pack of 6 bulbs; I bought a pack recently for under $9 including 6% sales tax) so if both fail just after five years of operation, we've spent $13.29 for operating the LED bulb and we've spent only $7.17 for the CFL, for a CFL savings of $6.12 (or we could buy 3 more CFL bulbs).
Even if I did this calculation with the Lights of America (LOA) bulb, we'd still save money using the CFL bulb. The LOA bulb uses 1.5 watts so 1.5/6 = .25 so 0.25 * 3.29 gives us a cost of two-year operation of $0.82. The cost of the bulb was ~ $10 so we have $10.82 total cost minus the $7.79 for the CFL means using the CFL we would still save $3.03.
How long does an LED bulb have to last (hrs and years, assuming three hrs/day) for it to break even with a CFL bulb?
Most LED bulbs use about 20 - 50% of the energy of a CFL bulb. Some of the newer GE LED bulbs cost upwards of $25 and more, which would throw these calculations off. On top of that they use every bit as much electricity as the CFL bulbs. I've seen 100W equivalent LED Bulbs using 20 Watts of electricity, which is the same as the CFL bulbs of the same equivalency. I would strongly advise not buying such bulbs until the cost of the bulb is the same as the comparable CFL bulb.
Example: For a 60W equivalent CFL or LED bulb:
CFL: http://www.homedepot.com/s/cfl%2520phillips?NCNI-5 search on "7.98"
HomeDepot.com $7.98/4-pack (Philips 13W) - good warranty, my experience. (Yes, Home Depot used "phillips" two Ls in the URL even though they use, correctly, "Philips" for every Philips bulb on the web site.)
LED: http://www.ebay.com/itm/like/281085913478 - Two Feit Electric 13.5 Watt LED Omni - 60W Incandescent Replacement Bulbs, US $39.95. That's $20 each, about six times more than the CFL bulbs. It is also interesting to see on the Feit bulb package in BIG RED CAPITAL LETTERS: "LASTS 22.8 YEARS." In this case the LEDs cost about six times more and use 0.5W more than the CFL bulbs, so they will never cost less to buy and operate than the CFL bulbs. The photo of the package did not show warranty information.
Let's think about this. At best, the LED bulbs use half as much electricity as the CFL bulbs. But the LED bulbs have a much shorter warranty period which indicates that even the manufacturer doesn't expect the bulb to last much longer than 10 - 20% of the exaggerated life expectancy of the bulb, based on the life of the LEDs. This all adds up to mean that we will probably never be able to save money by buying LED bulbs.
So, where's the break-even point? Let's try to calculate this to see if that statement is correct:
Cost of operating for one year,
assume 3 hrs/day * 365 = 1095 hrs/yr
assume 1 KW = $0.10
assume 1 bulb lasts the entire time (for now)
Initial Cost(LED) + (CostToUse(LED)/yr) * Yrs = Initial Cost(CFL) + (CostToUse(CFL)/yr) * Yrs
The Cost To Use the bulbs (using 1 KWhr = $0.10) is:
LED: 1095*6W*0.10/1000 = $.66/yr
CFL: 1095*10W*0.10/1000 = $1.10/yr
$10 + Yrs*(.66/yr) = $1.67 + Yrs*($1.10/yr)
10 - 1.67 = Yrs * (1.10 - .66)/yr
8.33 = Yrs * (0.44)
Yrs = 8.33/.44 ~ 18.9 years.
NOTE: The spreadsheet does not round the numbers and so shows the break-even time as about 19.02 years. (This is about nine years longer than CFL bulbs state as their expected life, so if we use the cost of two CFL bulbs, this reduces the break-even point to about 15.2 years.)
At the present cost of these bulbs and expecting the bulbs to last almost the complete exaggerated life expectancy of the LEDs means that the LED bulbs will never pay for themselves when compared to the CFL bulbs if the bulbs all die in under 18.9 years. This is 3.8 - 9.5 times the warranty periods I've seen for LED bulbs. It simply isn't likely to happen.
The exaggerated claims of the LED bulbs is that they will last from 22 to 28 years, yet the warranty period, has been at most, five years and as little as two years for the LED bulbs I have purchased.
The CFL bulbs have warranty periods of five, six, and seven years. The life expectancy claimed is 9 to 10 years. To be comparable, the LED manufacturers will have to increase their warranty periods to more than 55% of their stated life expectancy of the bulb, as based on the life of the LEDs. This means that for an LED bulb claiming a 2- year life expectancy, the warranty period should about 12.1, years and for a bulb with a life expectancy of 28 years the warranty period should be about 15.4 years. I'd gladly buy them with warranty periods of 11 and 15 years, but no longer if they are only two to five years. I want to see the LED bulb manufacturers put their warranty backing where their expected life claims are. If they don't trust their bulbs, why should we?
None of the CFL bulbs I've used have lasted longer than two years, let alone outlasted the warranty period. However, every failed CFL bulb I've bought, that was manufactured by a known, reputable company, has been replaced for free (or for just the sales tax) under the warranty. The LED bulbs don't yet seem to be any better, with the first one I bought failing in less than two years.
Big warning: to get the full use of the warranty, when using LED bulbs, you may need to put it into service a soon after buying it as possible and certainly no longer than a few days.
No matter which LED bulb you buy, only buy it as you need it. Never buy a bulb and have it wait on the shelf to be used for even a year or two since even waiting one year, in the case of some LED bulbs, means you've lost half the warranty period. In my recent experience with both GE and Philips, I was only asked how long the bulb lasted. To be sure of this, I always use a permanent marker to write the date on the bulb's base as to when it was put into operation.
At present, I'm sorry to say, it doesn't look to me as if buying an LED bulb is cost effective when compared to the present CFL bulbs. Only time will tell with the other LED bulbs I'm now using. However, the revelations of these calculations have decided for me that I will not be buying any more LED bulbs until the cost is the same as the CFL bulbs and until the warranty periods are also extended to be comparable to the CFL warranties or better yet, are at least half of the expected life time based on the life of the LEDs, which means about 11 to 14 years.
If you would like to play with these numbers for your specific bulbs, you can download the spreadsheet I developed for this purpose. It is called, CFLvsLEDcosts.xlsx and is available by clicking on the link to the left..
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