Construction Operations Building Information Exchange (COBie)
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This page is related to BuildingSMART International. All articles in the OSArch wiki related to buildingSMART can be seen in the BuildingSMART International Category |
COBie is a Model View Definition of IFC for the purposes of computer aided facility management. It describes the exchange requirements of what data needs to be present in an IFC file. The official specifications are found in the National BIM Standard Section 4.2. These requirements include:
- A list of IFC classes that are considered to be maintainable assets and which are not
- A list of properties that should be defined for maintainable assets to be useful in facility management
- Guidance on which properties are considered to be less important, which are more important, and which can be auto-generated by your BIM authoring tool
The specification also outlines three ways to present COBie data:
- As an IFC-SPF file (.ifc)
- As an IFCXML file (.ifcxml)
- In SpreadsheetML, a proprietary XML specification tied to Microsoft Excel 2003 (.xls)
At the moment, the BlenderBIM Add-on is the only known tool that is capable of producing a fully COBie compliant IFC-SPF file in a straightforward fashion. All other tools require a large amount of workarounds. No tool is currently known to be capable of producing a fully COBie compliant IFCXML file.
The spreadsheet form of COBie was originally designed for three purposes:
- If a user wants to view COBie data and are incapable to view it in its IFC-SPF data and lack the technical expertise
- If project stakeholder lacks the funds to invest in IFC-based COBie data
- If the project scope is small, and a spreadsheet is sufficient to capture the data
Despite this original intention, the COBie spreadsheet format is currently the most popular format.
The COBie specification states that there is no difference between the three formats. However, this is not accurate. The specification describes a mapping from the IFC-SPF format to the spreadsheet format. This mapping is a "many-to-one" mapping, describing a series of ways to process potentially multiple data points into a single cell in the spreadsheet. Therefore it is possible to convert from IFC-SPF or IFC-XML into SpreadsheetML, but not vice versa. The mapping is also prone to ambiguity due to its usage of natural language.
For BIM authoring tools that provide both an IFC-SPF and SpreadsheetML output, it should be assumed that the mapping is not correctly followed. Only two tools are currently known that implement the mappings correctly: the BlenderBIM Add-on and the BIMServer COBie Plugins (Note: this is in theory, both have not been independently audited).
Common deviations from the COBie specification
| IFC Class | Predefined Type | Notes |
|---|---|---|
| IfcCovering |
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