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By daviddelven

I wonder why the class IfcSpatialZone appears in the IFC Schema when setting up the Property Mapping in IFC Translator, if you cannot generate any geometry and map it to that class using the Type Mapping setting. ... alzone.htm


On the other hand, you can export any geometry to IfcSite using the Type Mapping, and this class is a subtype of the IfcSpatialStructure, sibling of IfcSpatialZone sharing the same SuperType IfcSpatialElement.

The advantage of using this Class IfcSpatialZone is that you can attach a geometry into an independent spatial structure, not following the hierarchy of IfcSite>IfcBuilding>IfcBuildingStorey . We have several situations in which we have to inform about such those spatial structures, i.e. safety volumes, urban planning constraints, etc...

As we know, IfcZone is just an assignment, therefore a group of IfcSpaces, but there is a lack of own geometry, just the addition of Archicad Zones geometry.

Any thoughts?

Anotació 2020-04-09 180452.png
Anotació 2020-04-09 180452.png (45.73 KiB) Viewed 700 times
User avatar
By Christophe Fortineau
Hello David,

I've read your post into Linkedin today for the first time. I'm not sure to understand.
Why not following the hierarchy of IfcSite>IfcBuilding>IfcBuildingStorey ?
Can you give me an example ?
User avatar
By daviddelven
Hello, Christophe

Glad to receive your feedback.
Let me explain a little bit with some real use case examples, among several ones in which you do need other spatial structures:

Construction sub-areas during building activities, fire safety zones, lighting, security areas, evacuation simulation, indoor navigation, scanning areas, spatial reservation (MEP, maintenance, functional spaces, clearance, ....).

The typical (but not explicitly established in the standard IFC schema) hierarchy of IfcSpatialStructureElement classes (IfcSite, IfcBuilding, IfcBuildingStorey, IfcSpace) is too logically partitioned, too static. Even other types of classes such as IfcZone (subclass of IfcSystem) does not include shape representation and are just a collection of the IfcSpace areas included.

In all the above cases there is a need for explicitly identify zones or part of other spaces or rooms related to particular roles or activities or purposes.

This class has a huge potential within the different lifecycles processes. Right now it is being discussed with some IFC experts such as Yoshinobu Adachi or Gianluca Genova in order to boost better software implementations. That is why I am asking here in the Graphisoft Archicad forum, since 2019 already IFC4 Architectural Reference Exchange EXPORT certified.
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By Christophe Fortineau
Hello David,

I have never needed such a BIM model structure but now understand its objectives very well. Thank you. Even if I don't need it, I want to understand this problem. So I wonder about the possibility of structuring a model of which certain elements are both in fire safety zones and security areas. How can the structure of the model be organized if an element can be found within two branches of this spatialization?
User avatar
By daviddelven
Hello, Christophe.

You are talking about elements, which is another layer of this matter.
If you want to track elements according to the different spatial structures you decide in your model/s. As you already pointed out, elements can only be contained into "one" IfcSpatialStructureElement subtype (Site, Building, Storey or Space) and also into an IfcSpatialZone instance. Then the IFC Schema provides with the relationship "IfcRelReferencedInSpatialStructure", which means that you can reference any element to more than one IfcSpatialStructureElement or IfcSpatialZone instance.

So, containing and referencing are both compatibles although there is the constraint of just one container per element.
User avatar
By LaszloNagy
Hi David,

I have a question. You mentioned that any number of "IfcZone" entities can be created in the bottom left corner of the IFC Project Manager and IfcSpace elements can be added to them. Could you tell me more about why this is not suitable for your purposes? Would you like a 3D model geometry generated for such IfcZones based on the 3D geometry of the IFCSpace elements included in it?
User avatar
By daviddelven
Hello, Laszlo.

IfcZone does not have its own shape representation.
We need a non-hierarchical class to represent the purposes of IfcSpatialZone entity, not necessarily matching with IfcSpace partition strategy.

The examples I gave above in other comments explain the current need.
User avatar
By LaszloNagy
Yes, I agree with the current use case scenarios.
And I agree that it would be useful for it to have its own editable 3D geometric representation. I can imagine it could be even several non-adjacent geometries as that is also a possibility in real life.
I also think that it would be useful to have such a tool in Archicad that is separate from the Zone Tool. In Revit, there is the Room Tool (the equivalent of our Zone Tool) and there is a separate Area Tool, which lets you define larger areas consisting of Rooms.
The buildingSMART definition of IfcSpatialZone says this:
A spatial zone is a non-hierarchical and potentially overlapping decomposition of the project under some functional consideration. A spatial zone might be used to represent a thermal zone, a construction zone, a lighting zone, a usable area zone. A spatial zone might have its independent placement and shape representation.

I think it would be great to have such a tool in Archicad.

David, do you care to make this into a wish? That way we can vote on it and if it gets enough support, we can submit it to Graphisoft for consideration.
If you do make a wish, please post its link in this thread.