buildingSMART Forums

Support for HVAC maintenence zone export

Hi

We are planning to support (HVAC)maintenence zone export. Maintenance zone is modeled to our objects and customers has asked us to export them to IFC. This is how we do it now (not released version). Please see MaintenanceZoneIFC4.ifc (14.1 KB)

  • IFC4 exported as IfcBuildingElementProxy/PROVISIONFORSPACE
  • can consist of multiple separate zones
  • transparency is set

This is how it shows up in most of the viewers:


There you can see clearly how zones now don’t have references to main part.

What is missing now is reference from zone(s) to part that owns maintenance zones. We are planning to have that reference with IfcGroup.

Open questions are:

  • Is IfcGroup right way to make such connection?
  • Is it worth of having zones separately or should we export one object’s all maintenance zones as one zone?
  • How should we export maintenance zones in IFC2x3 since it is lacking PROVISIONFORSPACE. We have to support also IFC2x3 (it is widely used). Could we just set ObjectType == PROVISIONFORSPACE?

I think main thing is to find out best way to model such zones so that collision checks in viewers could do their jobs.

Comments?

MR 2020-03-18 > Please see a test how IfcGroup can be used AllInOneGroup.ifc
(24.0 KB). A pic how Solibri shows it:

There is other ways to group main part and zones also; we just have to find way that is most usable and convenient to receivers.

Kind regards,
Marko Ripatti

Have you considered adding a Clearance shape representation to your equipment object directly? That would forego the need to create 4 maintenance zones and group them. Also, Clearance representations are explicitly for the purpose so that collision checks can be performed.

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I think, it’s possible to use for maintenance purposes in IFC2x3TC2 BoundingBox and for IFC4.2 Clearance Geometry.

Thanks both! We will definitely take a look in that direction.

Hi @marko.ripatti, I agree with the other comments, look into clearance geometry, see e.g. https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/clearance-geometry.htm

However best if you can check how others, like Solibri, etc. supports multiple shape representations - here 1 “body” representation and 1 “clearance” representation.

Hi,

At the moment Solibri doesn’t support multiple representations, but we’re following this discussion with interest.

Pasi

If it helps, from my findings, Revit does support import of multiple representations, but doesn’t distinguish which is which. Revit does not support export of multiple representations.

The BlenderBIM Add-on supports export of multiple representations, and also supports import of multiple representations, but the import currently doesn’t distinguish between them.

Good to know, thanks. We are operating with own IFC exporter that is used also in our AutoCAD based solution so in that sense it is all in our hands. I’ll get back when we have sorted out what it requires to support multiple presentation.

MR 2020-03-24> Now we have a sample how to use clearance geometry. In that sample we use bounding box but if we go that way bounding box will be replaced by any number of solids. Please see MaintenanceZoneIFC4_ver2.ifc (8.0 KB)

At least FZKViewer can show body + clearance representation:


Comments?

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Looks good to me.

@Moult could you test how BlenderBIM Add-on reacts to MaintenanceZoneIFC4_ver2.ifc? To me it showed a real quick exit… maybe there is something wrong in our sample.

@trondholen could you also test same sample with DDS viewer. To me it seems that viewer did not like much that sample.

@marko.ripatti - tested, and I can replicate the problem :slight_smile: I believe it is a bug in IfcOpenShell causing the crash. The bug has been documented and I see that @aothms is already helping to fix it!

Glancing at the STEP source, though, it looks OK :slight_smile: I’ll keep you posted when the crash is fixed!

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