But, it created a lot of excess heat, which LEDs don't do. The heat came from below, in a metal housing full of electronics that convert 120 volts of alternating current to just a few volts of direct current. It's this heat that robs an LED of it's great efficiency.
The energy efficiency is described as lumens per watt. Lumens are a measure of light output, while watts are a measure of power input. At 450 lumens, this bulb's efficiency was 60: not so good, even compared to a CFL.
Now, that same company has the best bulb I can find. It produces 800 lumens of light, about equivalent to a 60 watt bulb. Yet, it uses under 10 watts. It's also dimmable, and on sale, and there are hundreds of them all over the store. The efficiency is 81.6 lumens per watt.
However, my relatively expensive meter measures it at 11 watts (92 milliamps / 1000 x 120 volts), so that drops the efficinecy to 72 lumens per watt. This puts it in the realm of all the other LED lights out there, and one CFL. Thankfully, it is very bright, and probably does put out "60 watts" of light.
Another calculation of efficiency is dollars per lumen-hour. Afterall, if a bulb costs you $10, but doesn't last any longer than an incandesscent, you've lost $9.50 (and you've wasted $9.50 in energy, which was used to build and transport and sell this bulb) . We must divide this $10 by the number of lumens you will get in its lifetime. This lifetime of lumens is it's expected hours of operation times the lumens it produces. And, energy cost must also be added.
So, let's use the 9.8 watt bulb I'm so excited about. If it really does last the 25,000 hours that it's rated, and your electricity is the same as the US average, 11 cents per kilowatt-hour, then the total cost is:
$11.98 + (25,000 * 0.11 * 9.8 / 1000) = $11.98 + $27.50 = $39.48
Total lumen-hours is:
25,000 * 800 = 20,000,000
Total cost is:
20,000,000 / $39.48 = 506,585 lumen-hours per dollar
Let's see what a 60 watt incandescent costs, if it lasts the typical 1,000 hours:
$0.50 + (1,000 * 0.11 * 60 / 1,000) = $0.50 + $6.60 = $7.10
1,000 * 800 = 800,000 lumen-hours
800,000 / $7.10 = 112,676 lumen-hours per dollar
The best CFL I could find produces 1640 lumens, similar to a 120 watt incandescent, yet this CFL uses only 23 watts. It makes 71.3 lumens per watt, better than many LEDs. If it lasts the advertised 12,000 hours, it's efficiency is:
$4.49 + (12,000 * 0.11 * 23 / 1000) = $4.49 + $30.36 = $34.85
12,000 * 1640 = 19,680,000 lumen-hours
19,680,000 / $34.85 = 564,705 lumen-hours per dollar
So the best CFL and best LED give you half a million lumen-hours per dollar, while the incandescent gives less than an eighth million. Amazingly, the CFL cost less in the long run.
Keep in mind that CFLs have been criticized for only lasting 3,000 hours, despite a 10,000 or 12,000 hour rating. Even so, 3,000 hours gives over 400 million lumen-hours per dollar.
$4.49 + (3,000 * 0.11 * 23 / 1000) = $4.49 + $7.59 = $12.08
3,000 * 1640 = 4,920,000 lumen-hours
4,920,000 / $12.08 = 407,285 lumen-hours per dollar
Here are many of the bulbs I found in September and October of 2013.
LED lights:
Utili Tech Pro 9.8w 800 lum 25,000 hrs round fins smoke dimmable $11.98 81.6 lum/watt
Sylvania Ultra 14 w 1100 lum $29.98 25,000 hrs 78.6 lum/watt
GE Energy Smart 11 watts 800 lum $15 15,000 hrs 72.7 lum/watt
Sylvania Ultra 12w 850 lum 25,000 hrs flood fins softwhite dimmable $27.98 70.8 lum/watt
GE Energy Smart 10 w 700 lum $20 15,000 hrs 70 lum/watt
GE Energy Smart 7 watts 470 lum $10 25,000 hrs 67.1 lum/watt
Utili Tech Pro 7w 450 lum 25,000 hrs round fins smoke dimmable $8.98 64.3 lum/watt
Utili Tech Pro 22w 1400 lum 25,000 hrs flood vents softwhite $37.98 63.6 lum/watt
Utili Tech Pro 8w 500 lum 25,000 hrs round fins clear $17.98 62.5 lum/watt
Utili Tech Pro 4.8w 300 lum smoke/clear 30,000 hrs $14.98 62.5 lum/watt
Utili Tech Pro 4.8w 300 lum candleflame smoke/clear 25,000 hrs $14.98 62.5 lum/watt
Utili Tech Pro 7.5w 450 lum 25,000 hrs round fins smoke $16.98 60 lum/watt
GE Energy Smart 12 w 700 lum $35 25,000 hrs 58.3 lum/watt
Utili Tech Pro 13w 750 lum 25,000 hrs flood fins softwhite $24.98 57.7 lum/watt
Utili Tech Pro 20w 1150 lum 25,000 hrs flood vents softwhite $29.98 57.5 lum/watt
Utili Tech Pro 4.5w 240 lum candleflame 50,000 hrs $9.98 53.3 lum/watt
Utili Tech Pro 4.5 w 240 lum 50,000 hrs $9.98 53.3 lum/watt
Utili Tech Pro 4w 200 lum candleflame clear 50,000 hrs $9.98 50 lum/watt
GE Energy Smart 1.8 w 75 lum $20 2 pack 15,000 hrs 41.7 lum/watt
GE Energy Smart 2.3 w 94 lum $20 2 pack 15,000 hrs 40.9 lum/watt
GE Energy Smart 2.5 w 80 lum $20 2 pack 12,000 hrs 33 lum/watt
CFL
Utili Tech Pro 23w 1640 lum cfl 12,000 hrs 2 pack instant on $9.98 71.3 lum/watt
GE Energy Smart 26 w 1750 lum $6.58 6 pack 10,000 hrs 67.3 lum/watt
GE Energy Smart 16/25/32 w 600/1600/2150 lum $7.98 2 pack 8,000 hrs 37.5/64/67.2 lum/watt
Utili Tech Pro 13w 825 lum cfl 12,000 hrs 4 pack soft white $6.49 63.5 lum/watt
Utili Tech Pro 13w 825 lum cfl 12,000 hrs 2 pack instant on $6.29 63.5 lum/watt
GE Energy Smart 13 w 825 lum $2.82 8 pack 10,000 hrs 63.5 lum/watt
Utili Tech Pro 13w 800 lum cfl 12,000 hrs 4 pack bright white $14.98 61.5 lum/watt
GE Energy Smart 20 w 1200 lum $12.88 4 pack 10,000 hrs 60 lum/watt
Utili Tech Pro 5w 300 lum cfl 12,000 hrs 1 pack instant on softwhite $4.78 60 lum/watt
Utili Tech Pro 5w 270 lum cfl 12,000 hrs 1 pack instant on daylight $4.98 54 lum/watt
GE Energy Smart 10 w 520 lum $5 6 pack 10,000 hrs 52 lum/watt
Utili Tech Pro 7w 300 lum round smoke 8,000 hrs 2 pack $9.98 42.9 lum/watt
Utili Tech Pro 7w 260 lum candleflame smoke 8,000 hrs $ 5.98 37.1 lum/watt
Utili Tech Pro 7w 250 lum candleflame smoke 8,000 hrs 2 pack $9.98 35.7 lum/watt
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