What is the meaning of "use 55 materials" for 50 energies?

"Materials" means the building materials for upgrading building and for sending Jacks' plane on a delivery. If you can use 55 building materials to upgrade a building or send Jack on a delivery, then you will receive 50 energy as a reward for completing that task.

Building materials include the 3 common materials (brick, hammer, wood), 1 uncommon material (paint), and 5 rare materials (porcelain, copper, glass, terracotta, and marble) and can be obtained from suitcases at the end of playing a scene and from star boxes. Your inventory for each of these materials can be found below Jack's deliver map.