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Comment by speps | Hacker News Reader

IIRC, it's not exactly "more energy efficient", but rather "brighter light bulbs mean shorter lifespan" so you use the energy better but it's not inherently using less energy, it's using the same energy to produce more light. It also explains why the light bulbs from TFA last so long, they're all pretty dim.

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> it's using the same energy to produce more light.

That is, by definition, more energy efficient.

Not if you need to produce a new light bulb

Not obviously so. The embodied energy of an incendescent lightbulb could easily be dwarfed by the energy used in its lifetime. The relative cost of the bulb and the energy used to run it would certainly point to this being the case.

To restate your point: it's highly unlikely that a $1 light bulb contains more than $1 worth of energy.

A $1 dollar bulb can blow through a dollar of energy in about 100 hours. 200 hours if its a 50W.

In the technology connections video he does the math to show that long life bulbs are just an all around loss.

(Bullshit numbers incoming)

If one "forever bulb" can only output 10 lumens @10 watts but you need 100 lumens, and a "one year" bulb can create 100 lumens @60 watts, the disposable bulb wins.

Wouldn't hotter bulbs mean less energy wasted as infrared light?

You mean more?

Turns out it's less.

Cooler bulbs seem to generate a larger fraction of their energy in the infrared. Hotter bulbs generate not only more light, but a greater fraction of that light is visible.

This is easier to think about, if you consider the extremes. A very low power bulb generates no visible light, but still consumes energy. This is super inefficient. At higher temperature the peak shifts to longer wavelengths (i.e. visible). You can compare the black body radiation at different temperatures using Planck's law.[1]

[1] https://en.wikipedia.org/wiki/Planck%27s_law#/media/File:Bla...

>At higher temperature the peak shifts to longer wavelengths (i.e. visible)

Shorter, not longer.

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