I've wanted to reply to this thread for some time (probably 6 months) but I wanted to try to understand the various (especially Paul's) position more fully.
paul wheaton wrote:if you are trying to save energy, and you are still using a clothes dryer, then you really should not be exploring "which light bulb saves the most energy"
Heating and cooling use more energy - so those should also be explored first.
This is hugely, massively, ridiculously important. Using the dryer once uses as much power as months of Paul's lightbulbs.
paul wheaton wrote:if you really think picking out which light bulb to use will save you that much energy, there is a very good chance that exploring your lighting habits will save you far more energy (money) than trying LED.
Also hugely, massively, ridiculously important.
paul wheaton wrote:Next up: incandescent light has two big properties: high quality light + radiant heat. Radiant heat, when pointed at a person, is more efficient than convective heat - which is the most common way that people heat a home. I live in montana. And when it gets cold outside, the days happen to get much shorter. So when I need more light, I happen to also need more heat. A twofer.
This is the central tenet of Paul's point and very important.
Radiant electric heat has been used in factories and churches for decades. This is because they don't heat the air which takes a huge amount of energy but only heat people (oversimplified but we'll leave it there).
So why hasn't it caught on?
Because it's rubbish, ok that's too harsh. People, in general, don't like radiant heat.
1st problem; it's directional.
If you are sat in the same place it works brilliantly. As soon as you move out of the direct radiance you get cold again. Also having multiple radiant heat sources isn't a great solution because of the way the energy spreads Inverse-square-law
, which means that generally you get a lot more energy directly under one light, than you do when halfway between two lights.
2nd problem; it doesn't work nicely with other heating systems.
When I lived with my parents, my ceiling lights were behind my desk. The light was great for electronics, building computers and writing but I started to feel sick when sat there for 1/2 an hour. This was because I was overheating but because only my neck (lots of blood vessels, not a lot of nerves) was hot, my body couldn't work out why.
paul wheaton wrote:
In the scenario of cold climate area and the lighting is in winter and a party is using electric heat, then using incandescent light will pay for itself by not only reducing your heat bill, but if used correctly, the light bulb can actually REVERSE your heat bill. Proper use of an incandescent light bulb can save HUNDREDS OF DOLLARS PER YEAR. Maybe even THOUSANDS! In fact, for any type of heat, proper use of an incandescent light bulb can dramatically reduce your overall heat bill - and whatever you use for heat is going to use FAR more energy than what you use for light.
So this works if;
you stay relatively still when you want heat,
when there is one heat source per person &
it's the main form of heating.
It doesn't work as well in communal spaces and as soon as you stop using incandescent for heating, the modern leds are 'better' than modern incandescents.
paul wheaton wrote: Unlike CFLs, the amount of light it gives off five years later is the same as when it was brand new.
Not quite, the 10,000 hours life isn't based on the mean time between failures but on when the individual leds only put 70% of their original light. The leds should then continue to work for much longer than that. I'm not sure if the 70% is used on the average led or if it is a minimum expectation and the average led could be still at 80%. So leds do lose light output over time but they should last past that point.
A quick note on toxicity and manufacturing energy.
A standard incandescent is quite simple and relatively non toxic but all of the components are very energy intensive to manufacture, especially distilling air to generate the argon filling.
Leds themselves contain a very small amount of very nasty stuff.
The drive components in a well matched DC system should just be a resistor which is a bit of metal film rolled up inside a bit of plastic- not particularly toxic and the resistor is reusable and should last decades if not centuries.
The drive components in an AC or poorly matched DC system involve some sort of integrated circuit chip (really nasty stuff), a lot of copper wire inside inductor and transformers, some simple resistors, some capacitors (similar construction to resistors but with a fairly toxic paste inside and the part most likely to fail).
The vast majority of the weight difference is made up of the copper coils which should be negated by lighter mains wiring and isn't particularly toxic anyway.
So although the components of led lamps are more toxic, I would guess that the volumes required are so much smaller that there isn't a huge difference in the total toxicity.
As Paul has said, it all boils down to how the technology is used.