Total cost of ownership for LED Lights?

Home depot actually has a nifty little CFL savings calculator, although it's hidden deep in a cluttered flash app:

http://www6.homedepot.com/ecooptions/index.html

Hit the "energy efficient" button, then the "light bulbs" tab

According to their estimations, swapping 10 incandescents for CFLs will save you about $34/year.

i too wonder the same thing.

on this group, cafemom, that i belong to, all the crunchy moms are up in arms about how spiral bulbs have mercury in them.

led's have no mercury and if they save just as much energy, or more, then it would be obvious to swith to those, right?

I found this info...

LED Light Bulb Savings

How much money will I save by switching to LED light bulbs? Life Span & Energy Saving Benefits of LED Light Bulbs vs. Incandescent Light Bulbs Incandescent 60 Watt Light Bulb Earthtech 2 Watt LED Light Bulb Life Span: How long will the light bulb last? 1,000 hours 60,000 hours How many bulbs used over 60,000 hour period 60 bulbs Only 1 bulb Bulb cost over 60,000 hours $40.20 (60 bulbs at .67 cents each) $39.99 Electricity Usage: kWh of electricity used over 60,000 hours 3600 kWh 120 kWh Cost of Electricity: 60,000 hours at 10¢ per kWh $360.00 $12.00 Total Cost After 60,000 hours $400.20 $51.99 Total Savings: Money saved by installing one Earthtech LED Light Bulb Total Savings $348.21 per bulb! Led Light Bulb Benefits Save money in electricity costs Instant on/off Light the color of daylight Works in cold weather Use only 2-10 watts of electricity (1/3rd to 1/30th of Incandescent or CFL) Can sustain moderate power surges Long lasting - up to 60,000 hour bulb life Durable bulbs with no fragile filaments to break from shaking and rattling Cool running (warm to the touch) - little heat compared to standard bulbs Directional lighting generates less wasted light Works with sensor activated lights Works with most dimmer switches

Organicgal - I think this is a perfect time for you to introduce yourself to the "Export to Wiki" button. A classic issue with discussion forums is that this type of fantastic information can get buried in a thread somewhere and is hard to find for more novice internet users. Take a stab at clicking "Export to Wiki" on your post, it will ask you for a name for your wiki article and move your post over there (it doesn't delete it here or anything.)

That way, if other Huddlers come across it and can add more details or anything, they can add their $.02 right to it. I'm happy to do this for you, but we'd like to have real users try it out so that we can make it better. Thanks for the great info!

For sure - the next step is to get the forum to leave a notification that says something like - "This post has been turned into a wiki called LED Savings Charts"

Great job - now if other folks have ideas or contributions to those wikis, they can add away...thanks again.

A while back I developed a formula for computing the total (tangible) cost of ownership of light bulbs, it works for incandescent bulbs, CFLs, and LED lamps.

The formula gives dollars per megalumen-hours, given:

initial-dollars: the initial cost of the bulb in dollars

watts-consumed: how much power the bulb consumes in watts

average-lumens: how much light it produces at any given time, on average over its lifetime, in lumens

thousand-hours-lifetime: how long it lasts in thousands of hours

dollars-per-kilowatt-hour: the cost of electricity in dollars per kilowatt-hour

If you understand that a kilowatt-hour is the consumption of one thousand watts for one hour, or one hundred watts for ten hours, etc., then you'll understand the megalumen-hours concept too, it's the generation of one million lumens for one hour, or one thousand lumens for one thousand hours, etc.  In other words, its a way of measuring the total light output of the bulb over time, just as kilowatt-hours is a way of measuring the total energy consumed by the bulb over time.  I chose megalumens instead of just lumens because otherwise the numbers come out like 0.00000...

dollars-per-megalumen-hours = ( initial-dollars + watts-consumed * dollars-per-kilowatt-hour * thousand-hours-lifetime ) / ( average-lumens * thousand-hours-lifetime / 1000 )

I used "average-lumens" because both CFLs and LEDs slowly lose their brightness over their lifetime, and usually the end-of-life point is chosen to coincide with then the bulb has lost 30% of it's initial brightness (so it still has 70% left).  Thus, in the examples below, for CFLs and LED lamps, I use an average-lumens value of 85% of the so-called "initial-lumens" (how bright the bulb is at the beginning of its life).  This assumes a linear fallof of brightness over time, which I can't say is actually true, but it simplifies the formula greatly.

Here are some examples (all assuming $0.10/kilowatt-hour):

60-watt incandescent bulb, 800 lumens, 1,000 hours lifetime, $1.00 initial cost:

( $1.00 + 60 * $0.10 * 1 ) / ( 800 * 1 / 1000 ) = ( $1.00 + $6.00 ) / 0.8 = $8.75 / megalumen-hour

15-watt CFL bulb, 800 lumens (680 average), 6,000 hours lifetime, $5.00 initial cost:

( $5.00 + 15 * $0.10 * 6 ) / ( 680 * 6 / 1000 ) = ( $5.00 + $9.00 ) / 4.08 = $3.43 / megalumen-hour

7.5-watt LED lamp, 800 lumens (680 average), 50,000 hours lifetime, $100.00 initial cost:

( $100.00 + 7.5 * $0.10 * 50 ) / ( 680 * 50 / 1000 ) = ( $100.00 + $37.50 ) / 34 = $4.04 / megalumen-hour

Note that the CFL does come out a little better than the LED lamp in this case, but if the initial cost were dropped to more like $75.00, the LED lamp would start to have a better bottom line.

Note also that this formula does not consider less tangible factors like the cost of frequent changing of bulbs in difficult-to-access locations, or the cost to the environment of mercury escaping from improperly-disposed-of CFLs, or the additional CO2 that is put into the atmosphere to generate the extra electricity used by both incandescent bulbs and CFLs compared to LED lamps.

Edited by bobkart - Fri, 09 May 2008 08:56:38 GMT

Edited by bobkart - Sat, 10 May 2008 01:35:41 GMT

BOB - this is a really cool way to think about this! I love it.

It even makes it relatively straightforward to calculate the price-point at which the purchase of LEDs is a totally justifiable financial decision, not just an environmental one. This is definitely another candidate for a great wiki article.

I'd like to try to apply this formula to some of the other bulbs we have in the system and see how things shake out. Thanks again - awesome!

I went ahead and threw the info into a wiki - I'd love for you to take a look and make some edits Bobkart - thanks again!

It's called "Lifetime Costs of Light Bulbs"

Thanks Deej, I did take a look and made some minor edits.

I couldn't see how to do it but you must know, could you use this image for the LED lamp in the wiki page?

http://www.ccrane.com/images/medium/geobulb-led-light-bulb.jpg

Thanks for your help!

All set Bob - in the future, if you save an image to your computer, you can embed it in forums and wikis using the little mountain range looking button from the toolbar - if you mouse over it, it says "insert/upload image", then it will ask you to browse for the file on your computer and that's it. You can even re-size it within the window.

Hope that helps - PM me if you have any questions.

Thanks Deej.

I'll try the upload thing next time I get a chance.

EDIT: Actually I guess I did that when I changed my avatar.

Bobkart: I like your estimation for LED lights.

Megalumen hours provides another measurement to compare lights.

LED lights are very cost effective here, what with electricity costs around 37 cents a kWh for commercial and about 35cents/kWh for residential.  The cost of Megalumen hours will vary from location to location. I believe we have some of the highest energy costs in the nation so posted Megalumen costs in some cases might only be 1/3 of of what it is here...

When you get into commercial areas there are other costs associated with older inefficient lighting products. If you have incandescent lights, as a business, there are the costs of paying someone to change burnt out lightbulbs. Also certain areas might have to be closed down temporarily while changes are being made.

Yes, clearly higher electricity costs shift the balance in favor of the more efficient lighting technologies despite higher up-front costs.

And I agree that the formula leaves out less tangible costs like frequent changing, as I mention at the end of my first post in this thread.

Here are the same three bulbs as in that post but with $0.35 used instead of $0.10 for the cost of electricity:

60-watt incandescent bulb, 800 lumens, 1,000 hours lifetime, $1.00 initial cost:

( $1.00 + 60 * $0.35 * 1 ) / ( 800 * 1 / 1000 ) = ( $1.00 + $21.00 ) / 0.8 = $27.50 / megalumen-hour

15-watt CFL bulb, 800 lumens (680 average), 6,000 hours lifetime, $5.00 initial cost:

( $5.00 + 15 * $0.35 * 6 ) / ( 680 * 6 / 1000 ) = ( $5.00 + $31.50 ) / 4.08 = $8.95 / megalumen-hour

7.5-watt LED lamp, 800 lumens (680 average), 50,000 hours lifetime, $100.00 initial cost:

( $100.00 + 7.5 * $0.35 * 50 ) / ( 680 * 50 / 1000 ) = ( $100.00 + $131.25 ) / 34 = $6.80 / megalumen-hour

So your point is well-taken, the LED lamp in this example is already more cost-effective (just in terms of the costs addressed by the formula) than the corresponding CFL, without the 25% reduction in up-front cost that is needed to make it compete with the CFL when electricity is only $0.10/KWh.

I do these reports all day long and if anyone is interested, I can send them a copy of my energy savings analysis on replacing 75W T12 Fluorescent tubes with our LED PAR38 21W bulbs for several buildings here in New York City.

A 75-watt T12 Fluorescent lamp . . . what is that, like 8 feet long?

I'm having a little trouble seeing how a PAR38 LED lamp can be used to replace such a lamp.  Certainly the fixtures would need to also be replaced.  Do you have a link to this 21-watt PAR38 LED lamp?  I'd be interested in know it's luminous output since I imagine a 75-watt T12 would be somehwere in the range of 5,000 lumens, something I know a 21-watt PAR38 LED lamp can't do, but perhaps you are using 2-4 of them per 8-foot tube.

Yes you're exaclty right. They are 8 foot long. The hallways in the buildings are about 100 feet long with about 8 to 10 fixtures per hallway.  We're proposing to take out the fixtures and do a new installation with our LED PAR38 on our own Lumiere track lighting system. We plan on using 35 to 40 bulbs per hallway.

The T12 is 75W is actually about 6,100 lumens (5000k). However, a lot of the light is wasted as the T12 gives off light in all directions. We will be using a 40 degree beam angle in neutral white (4000k) that gives off about 1,400 lumens.

You can view the product details here:

http://www.ledwaves.com/product.php?productid=19653&cat=103&page=3

By switching to our LED PAR38s I estimate an electric savings of about $42,000 per year. This does not include maintenance or the disposal costs of fluorescents.

I'm trying to work backwards from that $42,000/year savings in electrical costs . . . assuming two 8-foot bulbs per fixture and the lights are on 24/7, at $0.20/KWh I come up with about 25-30 of those 100-foot long hallways.  At 25 hallways that's 1000 LED lamps, at $100 each that's $100,000 just for the "bulbs", not including the parts and labor cost of replacing all those fixtures.  So even at $42,000/year savings in electrical cost, it will still take multiple years to pay for the initial investment.

Don't get me wrong, I'm all for cutting down on energy consumption, I've replaced half of the bulbs in my house with LED lamps and am saving about 25% of my electric bill as a result (but at an initial cost of many hundreds of dollars).  So same situation here, many years to pay back the investment.

Any chance you could give us the details of how that $42,000 was arrived at . . .  just curious.  How many fluorescent bulbs per fixture, how many 100-foot-long hallways, electricity cost per KWh, and ballast overhead are basically what I need to be able to do the math myself.  Oh and how many hours per day the lights are on.

Sure, I can provide more details. The lights are on 24/7, and there about 450 T12 tubes for all 3 buildings. To replace all the tubes I estimated they will require 630 LED PAR38.

T12 Annual Power Consumption: 294,000 kw

LED PAR38 Power Consumption: 115,000 kw

Cost per kwh: $0.22

Avg Demand rate: $10.25 ( most people don't use this figure in their calculations)

T12 Annual Electric Cost: $69,000

LED PAR38 Annual Electric Cost: $27,000

Annual Energy Savings: $42,000

Annual Relamping Savings: $6,600

Relamping savings are calculated by using the half life of the T12 which is 6,000 hours. The half life of our LED PAR38 is 80,000 hours. To match the life of our LED PAR38, the T12 would need to be purchased 13 times over 9 years. The T12 is about $10 per tube.

There is an additional savings on the demand rate as that will come down with the lower power consumption.

The payback period would fall between 18 to 24 months. You're right that for residential use, the payback would take many years, probably at least 3 to 4 times longer. However they would also last longer since you use them less.