Regarding Energy deduction

Can someone explain when the system would deduct energy besides going downstairs and reviving members? No consideration about alchemy and trade CE.
I've bought the elevator pass, but I still found my energy was deducted in the following situations:
1. After killing all the monsters in a map, I left party to return to haven. 10 energy was deducted.
2. Quit the game by closing the game screen and then logging on. Some(2?) energy was deducted.
3. 2 energy was deducted without reasons when going downstairs.

1 sounds like you were on the elevator and then hit escape and return to haven instead of hitting the Up arrow. Game probably sent you down since you didn't give it the command to go up. Instant 10 energy used.
The others honestly sound like you weren't paying attention to your energy and counted it wrong.
~Gwen
4. 2 energy was deducted if I joined other's party and it had been at some depth, not 1, 8 or 18.