Fig. 1 shows the solution to the new clues suggested in the last post: the maintenance lift and the maintenance footbridge, and the air difusor (a black piece with holes over the statue). Conclusion: Something is happening on the back of the brick wall, what?
Each structural modulo has one air difusor is conected with an air handling unit by duct, see Fig. 2. The machine are placed on the lateral gallery, inside the building. Outdoor air is introduced by ducts from the glass wall to the machines and indoor air is extracted by ducts from the machine to the glasswall, see Fig. 3 and the first post. Do you remember "the holes" in the glasswall placed on the main facade?
Fig. 1. Museum maintenance elements (lift and footbridge), and one air difusor
Fig 2. Air difusors in the main gallery
Fig. 3. Machines and ducts placed on the lateral gallery, inside the building