Decomposition In a bim database, objects are usually organized in decompositions in which top objects are broken down into smaller, more specific objects. The purpose is to decompose a project into manageable components and to provide an understanding of how different project parts hang together. In a briefing model, the most important decomposition will be that of the requested spaces. The top element will usually be building or site which is then broken down into areas or building parts, which are in turn broken down into individual rooms or spaces. See page 38 for a more detailed explanation about this.For technical elements, there are predefined breakdown structures available. Good examples are Uniclass (uk) and Omniclass (us). Both are classification systems in which technical elements are numbered and categorized according to a specific structure that is familiar to the construction industry so parties can quickly find the information they need. In Uniclass, for example, a movable partition system is listed under Ss_25_12_65 Panel partition systems, which is in turn listed under Ss_25 Wall and barrier systems.As well as such technical decompositions, the brief can contain breakdowns of more abstract objects, such as user activities to express functional requirements. The activity office work can for example be broken down in sub-activities like making phone calls and concentrated computer work, which can be linked to different spaces in the model to explain the functional purpose of these spaces. Room breakdown Element breakdownBuilding ElementsEntrance area FinishesReception Floor \x04nishWaiting area Ceiling \x04nishWall \x04nishConference areaConference room - largeFurniture Conference room - smallO\x05ce furniture DecompositionsThis diagram shows a decomposition of spaces (left) and of building elements (right). The number of levels of the spatial breakdown will usually increase as the project progresses. For the purpose of briefing, however, decompositions do not have to go very deep. For example: a room object toilet does not need to be broken down into wash area and cubicles if the client does not have any specific requirements for those parts.