Is my LED light calculation correct?

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ctviggen

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Is my LED light calculation correct?
« on: 13 Jul 2013, 01:27 pm »
I was thinking of buying these:

http://www.homedepot.com/p/Philips-22-Watt-100W-A21-Household-Soft-White-2700K-Dimmable-LED-Light-Bulb-E-424432/203675471#.UeFSXm1yKNI

These use 22 watts and  produce 1780 lumens.  I believe Home Depot has them cheaper (at around $30 perhaps).  These would be to replace 72 watt, 1490 lumen bulbs.

If these are on for three hours per day (two are in play room and one is in family room), every day, on average, that would be:

50 watts (savings, 72-22)x3 hours/day x 365 days = 54750 watt-hours or 54.75 kw-hours.   

Considering our high cost of electricity in CT (about 17 cents per kw-hour), that would be 54.75 kw-hour x 0.17 dollars/kw-hour = $9.31.

Does that seem correct? 

If so, to me, a three to five year payoff seems like an incredibly long time.  Now, if they were on 8 hours/day, that would begin to get close to a 1-2 year payoff. 

Bob in St. Louis

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Re: Is my LED light calculation correct?
« Reply #1 on: 13 Jul 2013, 01:39 pm »
My house is never vacant, and the most commonly used (adjoining) rooms in the house have their lights on about 12 hours a day.
In all, there are 10 bulbs that are on half the time.  :duh:

This is a topic I've been thinking about for quite some time, just been too lazy to do anything about it.
So although I have no knowledge to offer, I'll be lurking and learning. Thanks for starting the thread.

Bob

Wayner

Re: Is my LED light calculation correct?
« Reply #2 on: 13 Jul 2013, 02:27 pm »
If  you use a dimmer, you can extend the life expectancy of the LEDs. I use them in my vinyl room, because they do not make any filament noise when in the dimmed mode.

I bought my Toshiba par 30 long neck lamps (3 of them) for $11.00 each on sale at Menards awhile ago. They are rated at 10.5 watts at full power. Get something that is on the warm side of the color index. These are at 2700 Kelvin so they match incandescent fairy well.

My model number is 11P30L/827/FL25 rated at 40,000 hours.

P.S., some dimmers may react weird with LED lamps. I use Leviton with them. They will lose their lite with about 1/2 the amount of dimming. It just extinguishes. Other poorly designed dimmers will cause the lights to flicker or fade in and out with intensity.

Wayner

ctviggen

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Re: Is my LED light calculation correct?
« Reply #3 on: 13 Jul 2013, 03:54 pm »
I've heard that about the dimmers.  They now sell dimmers that say they're rated for LEDs.

I've also been thinking of replacing my recessed lights with LEDs, but that's really expensive, considering I have 13 recessed lights in my kitchen, eat in kitchen, and living room. 

I have one LED light bulb now, but that's one we keep on all night for the kids.  So, I calculated its return on investment to be about 6 months, if used about 12 hours a day.  I don't mind a 6 month or a year return on investment, but when the return gets to 3-5 years, I can't justify it.

RPM123

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Re: Is my LED light calculation correct?
« Reply #4 on: 13 Jul 2013, 04:25 pm »
http://forum.allaboutcircuits.com/showthread.php?t=66823

I would like to get some, however, it appears that some of the cheaper bulbs can emit a lot of RFI, especially flood lights! See link. Anyone experience any RFI issues?

Wayner

Re: Is my LED light calculation correct?
« Reply #5 on: 13 Jul 2013, 07:14 pm »
I have 5 tuners in my vinyl room, with no issues. LEDs work on DC voltages, so the "driver" is a 120 to what-ever step down transformer, with a bridge rectifier in it and more advanced ones have chips to do the funky things with the LEDs (like RGB color ones).

From my experiences, the interference claim is a non-issue, at least in my set-ups.

To replace incandescent just to have LED just doesn't have to be. Again, dimmers can add life to the incandescent par lamps and give you more control over the light levels. You just don't need all that light if your not doing brain surgery, so I'd relax on that mission and wait until LED lamps come down in price.

Modern day dimmers have a solid state device known as a Triac. This device shortens the half cycle "on time" by the amount the dimmer control is moved. The more dimming effect, the less the half cycle "on time" there is. The one draw back for audio guys is that this action can make filaments "sing" when in the dimming mode and can be very annoying during quiet passages. LEDs solve this problem as there is absolutely no noise when in the dimming mode.

One word of caution, the dimmer must not be on the same branch circuit as your HI-FI is or you will have noise and perhaps other problems, so check first before jumping in on this one.

Wayner

mcgsxr

Re: Is my LED light calculation correct?
« Reply #6 on: 13 Jul 2013, 10:30 pm »
When I finished the basement this year, I added 21 pot lights.  All are on dimmers.  All of the dimmers are LED compatible, but at around $11 per bulb, I did not go for it to begin with.  I will in time replace all the halogens with LED bulbs, but for now I am leaving it alone.

My HT system is on several dedicated lines, so no worries there.

Bob in St. Louis

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Re: Is my LED light calculation correct?
« Reply #7 on: 13 Jul 2013, 10:40 pm »
My HT system is on several dedicated lines, so no worries there.
That's cause you did it correctly the first time, and "future-proofed" your room.   8)

Wayner

Re: Is my LED light calculation correct?
« Reply #8 on: 14 Jul 2013, 12:13 pm »
This is a project I finished for a local company, doing all the design work, and assembly for the ring lights. To put size into perspective, the large ring is 24 feet in diameter. The LEDs are on top and bottom and are shining thru some Ice White acrylic lens to make the led strips look continuous.

They are DMX controlled to achive color and intensity. This particular project was for Mt. Olympus High School in Utah, and had a total of 11 rings. The rings are suspended by aircraft cable.

This kind of lighting is expensive, even for commercial installations. However, the payback does come with time. The LED strips are 300mm long and are made by Osram/Sylvania. The strips have interconnection pieces so that 10 or 11 strips are run by the same driver and controller. Each controller has it's own DMX address.




Wayner

ctviggen

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Re: Is my LED light calculation correct?
« Reply #9 on: 14 Jul 2013, 12:27 pm »
We have dimmers on all our recessed lights (just bought this house, so I don't like the style of a lot of the dimmers, but they work).  For me, I'm considering LEDs for lights that are on a lot, such as kitchen lights.   We have 6 recessed lights in the kitchen.  I assume they're 75 watts each, so that's 450 watts.  If you have those on 6 hours a day, that's 2.7 kw-hrs per day.  If you could drop 62 watts per bulb (which is realistic), you'd save 2.23 kw hours per day.  The problem is the bulbs are still $35/bulb or so.  Although, unless my calculations aren't correct, I get a return on investment of about 1.5 years (assumes no cost for the original bulb):

62 watts x 6 hours/day / 1000 kw/w = 0.372 kw-hour per day.  $35 / 0.372 kw-hr/day / 0.17 dollars /kw-hour =   553 days.

That's no too bad, I guess.  If they could halve the price of the bulb, then I'd jump in right away, assuming the length the bulb will last is really valid). 

ctviggen

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Re: Is my LED light calculation correct?
« Reply #10 on: 14 Jul 2013, 12:28 pm »
Very nice display!

mcgsxr

Re: Is my LED light calculation correct?
« Reply #11 on: 14 Jul 2013, 12:49 pm »
I like those rings a lot too!

I have LED undermount and overmount kitchen lighting, the undermount is on almost all day when I am home.  The pot lights in the kitchen are still halogen, there are 9.  The problem is the color of the LED's.  They really don't yet match the normal color of halogan, so my "other" users don't like them for use with pot lights.

I also installed LED under and overmount lighting in my pool table bar area.  I really like them (I use the warm white tubes) for that application.

Wayner

Re: Is my LED light calculation correct?
« Reply #12 on: 14 Jul 2013, 04:18 pm »
You need to find LEDs that are about 2700 K. That is the color of the old style, warm color incandescent. The manufacturers of these are also screwing around with color temperature and if you are not careful, can get them mixed up too. I do not like the blueish light of the cooler color temps, just too sterile for me.

Wayner

Bob in St. Louis

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Re: Is my LED light calculation correct?
« Reply #13 on: 20 Jul 2013, 05:18 pm »
You need to find LEDs that are about 2700 K.

We have a 4 bulb fixture in the kitchen, which requires GU10 ("pricey") bulbs. In the past couple days, we've had two bulbs expire.
Again, I take this as a preachable moment to my wife about the virtues of LED....
One of her apprehensions is her ability to get a migraine at the drop of a hat. Her migraines are often triggered by lights/lighting that aren't "easy on the eyes".
Her fear is that we spend a bunch of money on bulbs only to find out they're migraine inducing.

When you say 2700K, I found >>THESE BULBS<< which are 3000K.
Thoughts?

srb

Re: Is my LED light calculation correct?
« Reply #14 on: 20 Jul 2013, 06:18 pm »
Reading a number of reviews of 3000K bulbs, many say that the light is still too blue and cool, and even bluer and cooler when dimmed.  I would pursue the 2700K bulbs and there are a lot of them out there.

When comparing "equivalent" lighting intensity, the majority of the 5W LED bulbs say 50W equivalent, yet the lumens are ~300 compared to 400-500 lumens for the 50W halogens.  Guess you have to go by lumens for comparison and disregard the manufacturer's equivalent wattage spec, right?

Steve

Bob in St. Louis

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Re: Is my LED light calculation correct?
« Reply #15 on: 20 Jul 2013, 06:25 pm »
  Guess you have to go by lumens for comparison and disregard the manufacturer's equivalent wattage spec, right?
That sounds logical. It appears the same marketing B.S. that's rampant in the video projection/projector industry is in the light bulb industry as well.
Good to know about the temperature difference. I wasn't sure how much difference 300K would make.

Thank you Steve for the numbers and great information.
Once again, you're there to answer my question. As always. Not sure how you manage that, but I appreciate it very much.  :thumb:

Bob

JerryM

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Re: Is my LED light calculation correct?
« Reply #16 on: 20 Jul 2013, 06:48 pm »
We have a 4 bulb fixture in the kitchen, which requires GU10 ("pricey") bulbs. In the past couple days, we've had two bulbs expire.
One of her apprehensions is her ability to get a migraine at the drop of a hat. Her migraines are often triggered by lights/lighting that aren't "easy on the eyes".

Bob,

You should read a bit about migraine photophobia, especially how it relates to fluorescent, halogen, CFL and LED lighting.

If you want to save some time, do away with all of those types and hoard all of the incandescent bulbs you can, while you still can.  :thumb:

Have fun,

Jerry

Wayner

Re: Is my LED light calculation correct?
« Reply #17 on: 20 Jul 2013, 07:31 pm »
Reading a number of reviews of 3000K bulbs, many say that the light is still too blue and cool, and even bluer and cooler when dimmed.  I would pursue the 2700K bulbs and there are a lot of them out there.

When comparing "equivalent" lighting intensity, the majority of the 5W LED bulbs say 50W equivalent, yet the lumens are ~300 compared to 400-500 lumens for the 50W halogens.  Guess you have to go by lumens for comparison and disregard the manufacturer's equivalent wattage spec, right?

Steve

I think there is a little voo-doo going on with the "equivalent" crap, since all LEDs have a narrow beam pattern to them, like 30°, and a regular incandescent or CFL radiate in almost all directions. So while the LED might measure XXX lumens right in front of it, it's off axis tally will drop off sharply.

Now if your buying par style lamps, this is probably a good way to measure light output equivalency, but any other style (like A19 or A21) may be a little funny with the numbers. I haven't seen an A21 style LED for under $30 yet anyway, so I'm not in a big hurry replacing them until the price comes way down.

And Bob, try stay close to that 2700K as Steve has found that even 3000 k is too cool, if you want to blend the LED with incandescent or Fluorescent CFLs.

Wayner 

Bob in St. Louis

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Re: Is my LED light calculation correct?
« Reply #18 on: 20 Jul 2013, 08:35 pm »
........ and hoard all of the incandescent bulbs you can, while you still can.  :thumb:

My Mother is doing just that.  :lol:

Good to know guys. I didn't know 300K would make that big of a difference.
I was skeptical on the beam pattern too. Knowing an incandescent is "everywhere", and LED's are very focused.

Good info fellas....I'm absorbing.....

Mr. Viggen, I hope you don't mind me piggy backing on your thread.

ctviggen

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Re: Is my LED light calculation correct?
« Reply #19 on: 20 Jul 2013, 08:53 pm »
I've given up on compact fluorescents, as they don't last as long as they say they do and they don't produce the light output they say they do (or at least the wattage equivalent is off), and the color of the light drives my wife crazy.  There are some well-rated LED bulbs out there, but they're still a bit too expensive unless your bulb is on quite a bit.   

I just moved into this house and haven't figured out which lights will be on the longest.  In my former house, the kitchen lights were on a lot, as were the hallway lights.  In this house, the kitchen lights aren't on as much, as it's much brighter in the house right now (winter will be a different story).   

The one and only LED bulb I have now is doing a great job as a night light for the kids.  Until the LED bulbs come down in price, I haven't figured out where I can put them with a return on investment less than several years.

So, I'm incandescent basically all the way right now.  Even with incandescent, you have to watch the coler ratings.  We have two 72 watt bulbs in the playroom, and they each put out dramatically different light.