On each floor there is a way you can get one extra energy by touching the objects or things.

Year 1:
East Towers: The blank painting on the far left.
West Towers: Oranges painting (Next to Gryffindor's CR)
Lower Floor West: Fire lamp on the right side of the great hall doorway, Middle Soldier Statue.
Dungeons: Dobby.
Castle Grounds: Brown stick, in between Whomping Willow and Hagrids Hut .

Year 2:
Lower Floors East: The stack of books on the bench.
East Tower: Peeves behind the Divination Stairs.

Year 3:
Hogsmeade: Person standing in alley between Three Broomsticks and Honeydukes.

Year 4:
Forbidden Forest: Triangle Cobweb to the left of the Spider's Lair.