Construction phases in IFC – The concept of Status und Tasks

After the last blog post and video about Exporting Revit phases to IFC, I had an interesting discussion on LinkedIn about the possibilities of using statuses and tasks in IFC.
I invited Dion Moult to have a more in-depth conversation about this topic, as he has a lot of experience with IFC in practice as well as in development, and am sharing a short summary here - the entire conversation can be found in my current YouTube video and I can only recommend anyone interested to watch or listen to it:

Basics

The IFC schema describes standard properties that are assigned to corresponding property sets. These are the characteristics that buildingSMART considers to be relevant for most projects - but their number is still considerable. The properties that occur in almost all projects are in the so-called Common Property Sets and are supported by all common (certified) software solutions.
Here is an older blog post on this topic (please note: it is automatically translated from German and not revised yet - you can also check out my Youtube videos around property sets for better understanding) https://bim-me-up.com/allgemeine-ifc-eigenschaftensatze-common-property-sets/

What is the Status in IFC?

Most elements defined in the IFC schema have in their Common Property Set the STATUS property, which can take on some predefined ​​(Enumerated) values:

standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/penum_elementstatus.htm

At first glance, this looks similar to Revit phases - but there are a few important differences and limitations:

  • Revit has built-in phase filters that support usage of several phases in a project and map the current element status to a specific phase - in IFC, however, the status applies globally to the entire project, so that complex projects are not supported by the IFC status.
  • Not all elements have the STATUS property in the IFC schema - for example, this is missing in rooms (IfcSpace), which in many cases represents a restriction and requires the use of own properties.
  • The common IFC viewers do not have preset “phase filters” - these usually have to be configured manually, which requires the user to have the appropriate knowledge. This is also the reason why Revit only exports one phase or excludes demolished elements from the export.
  • The creation of filters in IFC viewers is made even more difficult by the fact that they usually require the specification of both, the PropertySet and the Property - since STATUS is part of the Common Property Sets, it is different for every IFC class, e.g. Pset_WallCommon for walls, Pset_BeamCommon for beams, Pset_WindowCommon for windows, etc.
    This must be taken into account when creating the filter rules and not all IFC viewers support filter rules with wildcards (*Common).

What are tasks in IFC?

The IFC schema has another definition that enables the mapping of complex tasks: IfcTask. This definition can be used for construction scheduling of complex construction projects, but is more comparable to scheduling tools than to phase planning in Revit.

standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/ifctask.htm

Important: IfcTask is not part of the Coordination / Reference View MVD, which is used by buildingSMART for the certification of BIM authoring software, so it is not exported from Revit or related products. Admittedly, construction scheduling is typically not carried out in the planning software or by the architect, but in special tools that are intended for this purpose.

Conclusion

Due to the increasing importance of data and data workflows in our industry, it is clear that authoring tools such as Revit only represent a relatively small part - from the perspective of the entire project or building life cycle - and that a seamless and reliable data transfer is becoming increasingly important.

An IFC today represents a data package from A to B - in the future we will have to enrich these data packages with various tools throughout the entire life cycle - but for this to happen, both the tools and the IFC standard must continue to develop. As Dion says at the end:

The real bit which IFC shines is standardization, a core, a foundation you can trust that is ISO standardized and yes, we spoke about some seemingly basic flaws like spaces missing the status property, but over time those flaws do get fixed and over time we just get better and better as an industry.

Dion Moult

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