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Comment by vladvasiliu | Hacker News Reader

To me, this looks like a rather different use, actually, which wasn't practical before: daytime lights for dark dwellings.

I don't think that many people blast 100 W LED lights at night, which is the classic use-case of incandescent bulbs. And if they do, they probably replaced much more powerful bulbs.

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This is exactly the rebound effect. The Wikipedia article unfortunately makes it out to be a Bad Thing and frames it as a wasteful increase in energy usage. It clearly isn't if you look at the given examples or think of some yourself. The example of LED lightbulbs, as you point out, shows that there is an existing need that was not being met due to the previously high cost of generating a lot of light indoors. An increase in efficiency allows that need to be met, energy consumption rebounds to the previous levels because the available money in the system hasn't changed. It's perverse that people suggest we should tax that extra efficiency to prevent such things happening, that would effectively hobble technological innovation because 1) why would you choose the more efficient option if it costs you exactly the same and 2) you are no longer freeing up that cash to be spent on novel uses of those more efficient systems. Again the LED example is illustrative, if you taxed them to the point that it is just as expensive as before to make the lighting in your room a closer analog of daylight then a lot of people, myself included, would simply stick with incandescent lighting since it has a nicer quality and you wouldn't be seeing any increase in activity around creating better indoor lighting by using more LED lights.

The same could be said for any example where the rebound effect applies, which is pretty much every technological advance in human history.

There is a blurry line between "new use case" and "more of the same old", I believe.

In transportation for example : cheaper fuel makes it easy to import exotic fruits from far away (avocado?). It is arguably a new use case : we did not eat those fruits before. On the other hand it does somewhat replace some local food (assuming we ingest the same amount of calories).

I did sometimes turn normal incandescent lights by day when I feel the light is too low. Now the threshold for "too low" seems to move slightly.

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