In BIM workflows, the term "design dimensions" is frequently used. Although these are essentially just specific attributes of objects in a building model, this information is considered so important that it is referred to as "design dimensions." These dimensions are generally defined as follows:
3D - The Model
The first three dimensions define the geometry of the digital building model.
4D - Scheduling
Construction scheduling is considered the fourth dimension of the BIM workflow—information regarding the planned construction phase or the specific construction period is stored within the objects using dedicated attributes.
This makes it easy to visualize construction phases and to plan and coordinate more complex work steps.
5D - Cost Planning
Cost planning is referred to as the fifth dimension—additional information regarding costs is stored within the model’s objects. In combination with (4D) construction scheduling, this makes it easier, for example, to obtain data for billing individual partial services, which is why 5D planning is primarily used by construction companies.
6D - Life Cycle Information
The sixth dimension refers to information that is relevant during the operational phase of structures. In building construction, this includes, for example, the key metrics commonly used in facility management regarding maintenance or cleaning intervals, energy consumption, manufacturer information, etc.
Less commonly, sustainability characteristics are referred to as the sixth dimension of planning, with information relevant to facility management then considered the seventh dimension.