🟢Model View Definitions (MVD)

An essential concept in IFC is a Model View Definition (MVD), developed by buildingSMART along with the IFC schema itself. An MVD is a subset of the IFC schema based on a specific use case. It defines the graphical and alphanumeric information, as well as their dependencies, to be included in the data exchange.

For instance, thermal simulations require information about openings in a wall and its materials, the structural analysis relies on information about the analytical model, while FM systems require only the basic geometry and focus instead on spatial information and specific component features, such as MEP system information, fire protection features, and usable areas.

The IFC schema on the left compared to an MVD as a subset on the right (c) Mark Baldwin, The BIM Manager

Complete List and status of MVDs developed by the buildingSMART: https://technical.buildingsmart.org/standards/ifc/mvd/mvd-database/

The following MVDs are used in the buildingSMART software certification process and also represent the most commonly used MVDs in construction projects:

Schema	MVD	Description	Revit certifications
IFC4	Reference View	Simplified geometric and relational representation of spatial and physical components to reference model information for design coordination between architectural, structural, and building services (MEP) domains	Architecture, Structure, MEP - Export Architecture, Structure, MEP - Import
IFC 2x3	Coordination View 2.0	Spatial and physical components for design coordination between architectural, structural, and building services (MEP) domains	Architecture, Structure, MEP - Export Architecture, Structure, MEP - Import

IFC Model View Definitions primarily support 3D geometry and property data. For the exchange of 2D information, such as plan views and annotations, it is recommended to use traditional formats such as DWG or PDF.

In addition, the intended use case covers only coordination in BIM coordination software and viewers, or as a reference in BIM authoring tools such as Revit. Importing (opening) an IFC file for editing purposes is not recommended and might lead to data loss.

With IFC4, buildingSMART started working on a dedicated Design Transfer View, which will allow a better one-way transfer of BIM data for editing purposes:

IFC4	Design Transfer View	Advanced geometric and relational representation of spatial and physical components to enable the transfer of model information from one tool to another. Not a „round- trip“ transfer, but a higher fidelity one-way transfer of data and responsibility.	Still under development - not part of the certification process

While IFC4 has many new features if compared to IFC2x3, the IFC4 Reference View has a smaller scope if compared to the IFC2x3 Coordination View, especially in the way the geometry is described. This leads to smaller file sizes and more reliable geometry representation for coordination purposes.

Opening (importing) an IFC4 Reference View in a BIM authoring tool is not recommended. For this use case, it is still recommended to use the IFC2x3 Coordination View, until the IFC4 Design Transfer View as well as the other specialized MVDs for IFC4.x have been finalized.

The scope of the IFC2x3 Coordination View compared to the IFC4 Reference View (c) Mark Baldwin, The BIM Manager (based on a visualization by AEC3)

When using the official buildingSMART documentation, it is recommended not to use the main schema documentation, but the dedicated MVD documentation, which can be accessed through the following link: https://technical.buildingsmart.org/standards/ifc/mvd/mvd-database/

This will avoid confusion, as the full IFC documentation may include definitions that are not part of the official MVDs.