Short Answer
vyzn does not invent geometry: areas and lengths are read directly from the standardized IFC base quantities of your imported BIM model. These are complemented by parameters already prepared according to SIA 380/1, and at building level vyzn aggregates the areas in compliance with SIA 416:2003.
Why It Matters
The derived areas and lengths feed directly into the downstream evaluations – for example the life cycle assessment, where material quantities are derived from the component areas. The quality of the results depends directly on the quality of the quantities in your IFC: if base quantities are missing or inconsistent, fallbacks or manual corrections take over.
How It Works in vyzn
vyzn reads the quantities directly from your imported BIM/IFC model and adopts the standardized IFC base quantities per component type:
- Slabs/floors: gross area (GrossArea)
- Walls: net side area (NetSideArea)
- Roofs: net area
- Windows and doors: area (Area)
- Columns and beams: length (Length)
vyzn combines two sources: the IFC base quantities from your model and complementary parameters already prepared according to SIA 380/1 (e.g. for orientation, insulation perimeter or shading). Depending on the selected mode, vyzn either only fills in missing values (enrichment) or specifically corrects existing values. You can review and adjust the assignment in the mapping if the model delivers no or inconsistent quantities.
At building level, vyzn then aggregates the room areas in compliance with SIA 416:2003 – including GGF, NGF/NF/HNF/NNF, VF, FF and KF as well as the building volume GV in m³. The energy reference area (EBF) is kept strictly separate and is derived solely from the SIA 380 energy reference classification (2015); it is deliberately not mixed with SIA 416 areas.
For lengths, vyzn can additionally derive thermal bridges automatically from the openings in the model: if the width and height of an opening are known, the length is calculated as the perimeter 2×(width+height). If only the area is available, the opening is assumed to be square and the length is estimated as 4×√area.
Practical Example
In the life cycle assessment, the material quantity per layer is derived from the net area of the component: for area-based KBOB 2022 indicators it results directly from the area, for volume-based indicators additionally with the layer thickness, and for weight-based indicators additionally with the density – each weighted by the material share of the layer.
Frequently Asked Questions
Does vyzn invent its own geometry?
No. vyzn reads the quantities directly from your imported BIM/IFC model and adopts the standardized IFC base quantities.
What happens if my IFC contains no base quantities?
Fallbacks or manual corrections take over. You can review and adjust the assignment in the mapping – and we are happy to look at your specific model together with you and check whether the areas and lengths come through cleanly.
How is the energy reference area (EBF) determined?
The EBF is derived solely from the SIA 380 energy reference classification (2015) – strictly separate from the SIA 416 areas and deliberately not mixed with them.