>You fill normal kettles at the time you use them, and you only fill them with the water you need.

But my espresso machine, it's got a pretty big (room temperature) reservoir, and only heats up the water as-needed. I mean, I probably have to fill it every second day, and that's with two people using it, and using the steamer.

Especially when my performance is impaired due to withdrawal, it seems a reasonable optimization to save the 'fill the damn thing up, but not too much' step.

>I am surprised that kettles don't have a think skin of insulation. I sometimes wonder how much energy could be saved by micro-enhancements like that.

All the electric kettles I've seen did have very thick insulation; it looked like they were intended to be left on or in standby all the time.