Abstract
Building Information Modelling (BIM) is potentially a great technology for the expression of knowledge, supporting interoperability and communication throughout the life-cycle of a building. In fact, Building Information Modelling is not a simple technology. It requires a sound understanding of a number of abstract modelling concepts. Next to being a technology, BIM can also be regarded as a method for making a low or non-redundant (i.e. with every fact represented only once) model of an artefact that is sufficient to realize it as well as simulating it before it actually becomes physical reality. This chapter discusses the modelling concepts of BIM: what is Building Information Modelling, what is a Building Information Model and what are its rationale and objectives? A clear distinction will be made between (a) that what is being modelled, such as requirements, function, boundary conditions, building configuration, connectivity, shape, processes lifecycle aspects and discipline views, and (b) how it can be modelled, such as through parametric models, part libraries, nD models, various representations and presentations, including visualizations. Finally, there is a brief discussion of relevant methods and languages for information modelling, such as ISO 10303 (STEP, EXPRESS), BuildingSMART (IFC, IFD and IDM), process modelling and recent ontology-based approaches.
Top1 Introduction
Building Information Modelling (BIM) has become a major understanding in building research and innovation of recent years. It used to be a specialist area within a group of experts working on research issues. But over the past few years, many software vendors as well as design and construction companies have been investing in the development and use of the technology. Although investments are relatively low and usage is mostly restricted to 3D design tools, this is expected to change once the industry sees the potential benefits.
Introduction of BIM is often accompanied by a lot of confusion. This is for a considerable part due to the fact that BIM requires abstract and conceptual thinking as well as the knowledge of a number of abstract modelling concepts that are commonly used in BIM.
This chapter discusses the most common modelling concepts of BIM. First, a few fundamental principles of BIM are explained: What is Building Information Modelling?, What is a Building Information Model ? and What are the rationale and objectives of BIM? Next, a number of concepts are discussed that are commonly used in building information models, such as composition, configuration, connectivity, parametric modelling and part libraries, functional requirements, discipline view models, modelling of building spaces, modelling of shape, and modelling of life-cycle views. Finally, there is a brief discussion of relevant methods and languages for building information modelling, such as ISO 10303 (STEP, EXPRESS), BuildingSMART (IFC, IFD and IDM), process modelling and recent ontology-based approaches.
This chapter does not discuss implementation issues or experiences. The chapter is of conceptual nature, for discussion of implementation issues, industrial experiences, best practices, etc. please refer to other chapters in this book.
Key Terms in this Chapter
UML: One important consideration in visual modelling is what graphical notation to use to represent various aspects of a system. This notation needs to be conveyed to all interested parties or the model will not be very useful. Many people proposed notations for visual modelling. UML stands for Unified Modelling Language. It is an object modelling technique that evolved as a result of the combined work of James Rumbaugh, Grady Booch and Ivar Jacobson. The Object Management Group (OMG) adopted UML as a standard for software modelling in late 1997. UML is now the de-facto standard for software modelling.
Building Information Model (BIM): BIM is an information model of a building (or building project) that comprises complete and sufficient information to support all lifecycle processes, and which can be interpreted directly by computer applications. It comprises information about the building itself as well as its components, and comprises information about properties such as function, shape, material and processes for the building life cycle.
Parametic Object: A building is composed of geometric components and the geometric information is substantial for BIM. Parametric modelling provides mechanisms to translate and embed domain expertise as explicit geometric expressions that can automate generation of the building information—especially geometric information and that can facilitate the generation of a rich building model (Lee, G. et al, 2006). We define parametric objects as objects (or components) of which we all know, if the parameters that describe the object, are known. These are items where not designed to and have to be calculated. An example of a parametric object construction is a standard pre-element, a wall element or a plate for example. Although such items in terms of building and / or exact form are often quite complicated, there are only a few parameters needed to describe a body.
Model: A model is a representation containing some essential structure of some object or event in the real world. The boundaries and type of this representation is influenced by the scope, purpose and the viewpoint of the model (Adopted from Stockburger, 1996).
Object Orientation: The object-oriented paradigm is a different way of viewing applications. With the object-oriented approach, you divide an application into many small parts (or objects), that are fairly independent of one other. An object is a concrete manifestation of an abstraction; an entity with a well-defined boundary and identity that encapsulates state and behaviour - an instance of a class. A class is description of a set of objects that share the same attributes, operations, relationships, and semantics.
IFC: The Industry Foundation Classes (IFC) data model is a neutral and open specification that is not controlled by a single vendor or group of vendors. It is an object oriented file format with a data model developed by the International Alliance for Interoperability (IAI) to facilitate interoperability in the building industry, and is a commonly used format for Building Information Modelling (Wikipedia, http://en.wikipedia.org/wiki/Industry_Foundation_Classes, Accessed 7 July 2009).
EXPRESS / EXPRESS-G: EXPRESS is a modelling notation to use to represent various aspects of a system. EXPRESS-G is a graphical representation of EXPRESS but does not include the full richness of the data definition language.