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RE: GE Smart LED light bulb promises 17 years of service, nine-watt draw
@richardw66
A 11w CFL is "uncomfortably bright"? Really? My experience with 11w CFLs (equivalant to a 40 watt bulb in lumens) is that they do not provide enough light to do anything except avoiding tripping unless they are massed or supplemented with bright task lights.
On a equivalent lumen replacement basis and current cost, this GE LED bulb does not provide a compelling ecomomic argument, at least for lights that are bright enough to do something. Unlike almost all articles and commentators on the subject, I will provide my numbers.
GE claims a 25,000 hour or 17 year life span for their LED bulb. That is an average use of 4 hours per day, 365 days per year. Claimed life span is always suspect; I get a little over half on the CFLs I use on average, so lets base our comparison on 10 years at 4 hours/day (1460 hours/year).
I will also assume a lamp using a single 100 watt incandescent bulb for comparison. Based on the chart in my previous post, the bulb produces 1700 lumens. I currently buy them in bulk for about $0.50 for a bulb that is rated at 1500 hours, but lets assume it lasts 1000 hours; this means I will use 1 to 2 bulbs per year for a total of 15 bulbs. Currently, power cost here is about $0.11 per kilowatt hour. Lets assume a 3% inflation factor for electricity and replacement bulbs. Electricity consumption per year is 100w * 4 hours/day * 365 days/year /1000 w/KW = 146 KWH/year. Therefore, our total cost by year for the 100w are
Year elec cost bulbs/year bulb cost
1 $16.06 2 $1.00
2 $16.54 1 $0.52
3 $17.04 2 $1.06
4 $17.55 1 $0.55
5 $18.08 2 $1.13
6 $18.62 1 $0.58
7 $19.18 2 $1.19
8 $19.75 1 $0.61
9 $20.34 2 $1.27
10 $20.95 1 $0.65
Totals $184.11 $8.56
$192.67 Total Cost w/100w bulbs
Now using the GE 9w led at 450 lumens per bulb, it will take 3 bulbs to produce 1350 lumens; while this is only 80% of the 100w bulb, I'll give this to the LED. Lets assume we can get one of the LED bulbs for $40; we need 3 so our total bulb cost is $120. Electricity consumption per year is 3 bulbs * 9w each * 4 hours/day * 365 days/year /1000 w/KW = 39.42 KWH/year. Therefore, our total costs by year for the 3 9w LEDs are
Year elec cost bulb cost
1 $4.34 $120.00
2 $4.47
3 $4.60
4 $4.74
5 $4.88
6 $5.03
7 $5.18
8 $5.33
9 $5.49
10 $5.66
Totals $49.71 $120.00
$169.71 Total cost w/ 3 9w LED
My $27 savings over 10 years is less than compelling, especially considering that I will need to buy a replacement lamp to hold the required 3 bulbs for the necessary light.
When the 450 lumen LED bulb price comes down to $10-$12 each or a $40 LED bulb will produce 1500 lumens, an economic argument would be compelling. Until then, not so much.
What, you say, I don't need a 100w bulb, a 40w will do? OK, using the same prices, the math on that works out to a 40w bulb cost of $8.56 and a electricity cost of $73.64 totaling $82.20. The LED bulb costs work out to $40 and $56.57 electricity cost. My savings is $25.60 over 10 years, still less than compelling.
Once again, the cost argument is less than compelling when one looks at being an early adopter competing within an established commodity marketplace. There may be compelling arguments to adopt this LED bulb, but economics is not one of them.
A 11w CFL is "uncomfortably bright"? Really? My experience with 11w CFLs (equivalant to a 40 watt bulb in lumens) is that they do not provide enough light to do anything except avoiding tripping unless they are massed or supplemented with bright task lights.
On a equivalent lumen replacement basis and current cost, this GE LED bulb does not provide a compelling ecomomic argument, at least for lights that are bright enough to do something. Unlike almost all articles and commentators on the subject, I will provide my numbers.
GE claims a 25,000 hour or 17 year life span for their LED bulb. That is an average use of 4 hours per day, 365 days per year. Claimed life span is always suspect; I get a little over half on the CFLs I use on average, so lets base our comparison on 10 years at 4 hours/day (1460 hours/year).
I will also assume a lamp using a single 100 watt incandescent bulb for comparison. Based on the chart in my previous post, the bulb produces 1700 lumens. I currently buy them in bulk for about $0.50 for a bulb that is rated at 1500 hours, but lets assume it lasts 1000 hours; this means I will use 1 to 2 bulbs per year for a total of 15 bulbs. Currently, power cost here is about $0.11 per kilowatt hour. Lets assume a 3% inflation factor for electricity and replacement bulbs. Electricity consumption per year is 100w * 4 hours/day * 365 days/year /1000 w/KW = 146 KWH/year. Therefore, our total cost by year for the 100w are
Year elec cost bulbs/year bulb cost
1 $16.06 2 $1.00
2 $16.54 1 $0.52
3 $17.04 2 $1.06
4 $17.55 1 $0.55
5 $18.08 2 $1.13
6 $18.62 1 $0.58
7 $19.18 2 $1.19
8 $19.75 1 $0.61
9 $20.34 2 $1.27
10 $20.95 1 $0.65
Totals $184.11 $8.56
$192.67 Total Cost w/100w bulbs
Now using the GE 9w led at 450 lumens per bulb, it will take 3 bulbs to produce 1350 lumens; while this is only 80% of the 100w bulb, I'll give this to the LED. Lets assume we can get one of the LED bulbs for $40; we need 3 so our total bulb cost is $120. Electricity consumption per year is 3 bulbs * 9w each * 4 hours/day * 365 days/year /1000 w/KW = 39.42 KWH/year. Therefore, our total costs by year for the 3 9w LEDs are
Year elec cost bulb cost
1 $4.34 $120.00
2 $4.47
3 $4.60
4 $4.74
5 $4.88
6 $5.03
7 $5.18
8 $5.33
9 $5.49
10 $5.66
Totals $49.71 $120.00
$169.71 Total cost w/ 3 9w LED
My $27 savings over 10 years is less than compelling, especially considering that I will need to buy a replacement lamp to hold the required 3 bulbs for the necessary light.
When the 450 lumen LED bulb price comes down to $10-$12 each or a $40 LED bulb will produce 1500 lumens, an economic argument would be compelling. Until then, not so much.
What, you say, I don't need a 100w bulb, a 40w will do? OK, using the same prices, the math on that works out to a 40w bulb cost of $8.56 and a electricity cost of $73.64 totaling $82.20. The LED bulb costs work out to $40 and $56.57 electricity cost. My savings is $25.60 over 10 years, still less than compelling.
Once again, the cost argument is less than compelling when one looks at being an early adopter competing within an established commodity marketplace. There may be compelling arguments to adopt this LED bulb, but economics is not one of them.
Posted by Dave S2
14th Apr 2010