I want to revisit this topic with some updated facts. After some research I think that Paul's analysis is fundamentally incorrect.
I apologise in advance for the length of this post but I wanted to give Paul the respect his analysis deserves and to "show my working" so it can be discussed.
In terms of Paul's original argument my points of disagreement are:
1) The colour spectrum of a LED is fine, even better than an incandescent for working.
2) The life of LED globes is far greater than assumed and more importantly some of Paul's argument relies on life span possibilities that incandescent globes might be able to supply but don't
3) The efficiency of the LED is understated by 50%.
4) The benefits of heating using an incandescent is completely overstated
5) The cost manufacturing life-cycle is overstated.
6) The analysis provided only works for a particular geographical zone.
1) Light Spectrum or Colour Balance. Firstly this is a completely subjective judgement. I personally prefer the light of an LED as is is much more balanced than an incandescent which is overly yellow and makes it nearly impossible to judge the daylight colour of anything. My rating incandescent a yellow 8.5, LED a balanced 9. But as said this is a subjective argument, Paul's judgement is completely correct for his taste and wrong for mine. Basically as long as the colour spectrum is good for you, this is a non argument. There is also no difference between the colour spectrum of DC and AC LEDs they use exactly the same light generation components. The difference is that the AC LED globes also have an internal powers supply. I would also point out that there is an increasing range of colour temperatures available. Yesterday I looked and there were four in my local supermarket I expect many more online or at a speciality store.
2) Life of a LED globe: Paul bases his argument on a LED lifespan of 10,000 hours. He also stated that an incandescent can, not does, but can get better hours. The actual LED is is rated for at least 50,000 hours. Excessive heat can also shorten the life span and packing the components into a standard globe volume is not ideal for heat management. A typical supermarket LED globe is therefore down rated to 25,000 to 30,000 hours, most new models on my shelf were 30,000 hours+ In reality, those claims are really arbitrary—no one really knows how to define the lifespan of an LED quite yet. That's because LEDs do not burn out like an incandescent bulb, rather, their brightness slowly fades. So, if the lifespan of your LED is listed at 30,000 hours, that is the point when your bulb will most likely be shining at around 70% capacity (the industry assumes people notice a decrease in brightness at that point). So if you don't mind a drop in the light output you may get another few thousand hours before you need to replace the globe. Note that the rating is a guarantee and therefore is probably a significant understatement.
3) The efficiency of the LED is understated. In the article Paul states that LED's get 4 times as much light per watt. My direct experience is that with warm white is is 6 times and higher for the cool white or daylight colour temps. This value is backed up by many independent research articles.
4) Heating using an incandescent... Really? This is a benefit? Most of the world doesn't live in Montana and even in Montana, there is summer or so I'm told. I live in Australia in a warming world and the last thing I want is to pay for large amounts of waste heat when I want light. At a summer temperature of 107F I need cooling not by-product heat. I can get efficient heating and cooling at 7 watts of heat per watt of electricity unlike the one for one of the incandescent. If I want I can also get efficient spot infra-red radiant heaters. The incandescent doesn't produce efficient heat or light. Oh and also I like radiant warming on my face and upper body, when sitting at a desk. To use an incandescent I would need a spotlight in the face to accompany the heat, no thanks.
The argument about heat production as a benefit of filament globes only applies in cold climates, and then only in the cold seasons, and then only if you don't mind lights shining on you, and then only if it is dark when you want the heat (bit silly in the daytime). Basically obtaining heat from an incandescent is inefficient and often inappropriate. It is never free! Another way to think about this heat is that on average for every watt of "free" heating in winter you have a watt of cooling to manage in the summer. Obviously this varies with your location but globally it by definition will balance out. No free lunch here.
5) Manufacturing cost. Paul suggests there is $10 of energy costs in manufacturing an LED. Currently I can buy the equivalent of a 60W globe for $4.95 US (unsubsidised!). This amount includes manufacturing, two layers of profit (manufacturer and retailer), international transport and distribution. The energy manufacturing costs are more like $1 to $2. Note that the US has the worlds cheapest grid electricity costs at around 10c/KWh. Australia for example pays nearly three times as much. My costs are $AUD0.34 per KWh roughly $0.26 KWh. Even in the US my research says that power costs range from 9c a KWh to 28c a KWh.
Energy savings now look completely different $2 (taking the higher amount) and realistic bulb life spans. Using 30,000 hours for a LED, 1000 hours for a standard incandescent, 5000 hours for a high quality one.
Using Paul's "Energy costs"
Incandescent 100W: 100W for 30,000 hours = $300 + (6 globes at 0.10) = $300.60
LED 14W = 42+ (1 globe at $2) = $42.60. A killing for the LED.
Also missing from Paul's analysis is that the incandescent needs 30 lots of transport and 30 lots of packaging compared to one for the LED
But I think that this is not a correct costing. The retail price reflects much more of the whole life-cycle costs as it includes distribution costs and you can say that the profit margin (much higher for the LED) reflects the disposal costs. Equally the environmental cost of generating the electricity over 30000 hours of use dwarfs the increased environmental cost of a LED globe.
This costing is based on actual prices paid last week for globes and average electricity costs of $0.20 per KWh
One Philips Light Globe 13w 1430 lumens Warm Bc @ $15.00 30,000+ hour life
One GE incandescent 100W @ $2.00 1000 hr life
For 30,000 hours use
LED
1 Globe @ $15
14W*30000 Hours = 420 KWh = $84
Incandescent
30 globes @ $2 = $60
100W*30000 Hours = 3000KWh = $600
Conclusion
Environmental cost
$99 Vs $660
Power Consumption
420KWh of consumed power Vs 3000KWh
Units consumed (Manufucturing, transport, packaging)
1 Globe Vs 30 Globes
I'll take the LED right now and by the look of the new ones coming down the pipeline the analysis is only going to get better for the LED. The day of the incandescent is over.
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