In dRofus, it is possible to start planning the areas of defined functions early on in the project, then go on as the project progresses to detail in the areas of each sub-function, using this to plan room areas as the room programming starts and then compare it all with the design in the design process.
Below is a description of how this can be done. To simplify the explanation, an example has been used where the levels of the function structure are called "Department" (level 1), "Subdepartment" (level 2) and Sub-Subdepartment (level 3). As this naming structure is adapted in the interfaces, your function structure may give an according difference in naming structure.