Let’s start with the function of the interiors of a building or facility. Recent social developments have brought changes in the use of architectural constructions, or in other words, in the function they fulfil for the users. These changes point towards the mixed function of spaces, which are now multi-purpose, shared and, in a general and figurative sense, fluid. In fact, the disuse of single function buildings is increasing due to factors related to new working relationships and teleworking, as well as to efficiency requirements, or even simply to changes in the tastes of users and/or buyers and/or developers. These new interior designs leave aside the discrimination of space by function, even its formal separation with immovable physical barriers, in such a way that they optimise it and allow a greater number of hours of use.