I was just standing in an elevator with a sign that said: Send back to 0 after use to save energy. How would sending an elevator back to 0 without any people in it ever be more energy efficient?

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I was just standing in an elevator with a sign that said: Send back to 0 after use to save energy. How would sending an elevator back to 0 without any people in it ever be more energy efficient?

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Just because somebody puts up a sign doesn’t mean they know what they’re talking about. Outside of ridiculously contrived scenarios, moving an elevator more isn’t going to use less energy than not moving it.

I think the most energy efficient an elevator can be is taking people up and then bringing people down. If the elevator is on the ground floor, it will probably be in use and reach its highest destination before snagging several people going down.

Odds are that the person writing the sign had no idea what they were talking about.
Modern elevators are counterbalanced.
IE they have a bunch of weights attached to the car by cables that go down when the elevator goes up and go up when the elevator goes down.
Thus they cancel out the weight of the car.
The motors only have to lift the weight of the contents.
And at that, they’re only expending energy changing floors, not when they have the brakes engaged.

I have no idea if it would work like that but my guess: They generate electricity from the elevater when it descends (because of gravity) and then store it to power the motors when the elevater has to go up again.

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