# BIM/IFC models for QTO
Below is a concise, **Python-first** recipe that shows exactly how to plug an **IFC model** (provided with the QRF) into your **Quantity-Take-Off (QTO)** pipeline. It follows the **external-mode** pattern described in the BIM literature: the IFC file is **only a data source**; all logic runs in Python.
---
### 1. Install the core IFC library
```bash
pip install ifcopenshell pandas openpyxl
```
### 2. Load the IFC file and list every structural element
```python
import ifcopenshell, ifcopenshell.util.element as util
from pathlib import Path
model = ifcopenshell.open(Path("rfx_structural.ifc"))
# Example: grab every IfcBeam, IfcColumn, IfcMember, etc.
elements = (model.by_type("IfcBeam") +
model.by_type("IfcColumn") +
model.by_type("IfcMember"))
```
### 3. Extract the quantities you need
```python
rows = []
for e in elements:
# 1. Identity
name = e.Name or e.GlobalId
ifc_ent= e.is_a()
# 2. Geometry quantities (IfcElementQuantity)
qs = util.get_psets(e).get("Pset_ElementQuantity", {})
length_m = float(qs.get("Length", 0))
weight_kg= float(qs.get("Weight", 0)) # if the modeller exported it
area_m2 = float(qs.get("SurfaceArea", 0))
# 3. Material grade (IfcMaterial)
mat = util.get_material(e)
grade = mat.Name if mat else "Unknown"
rows.append({
"Item" : name,
"Type" : ifc_ent,
"Material" : grade,
"Length_m" : length_m,
"Weight_kg" : weight_kg,
"Area_m2" : area_m2
})
```
### 4. Build a Pandas DataFrame → instant QTO table
```python
import pandas as pd
df = pd.DataFrame(rows)
# Aggregate identical sections
qto = (df
.groupby(["Type", "Material"], as_index=False)
.agg({"Length_m":"sum",
"Weight_kg":"sum",
"Area_m2":"sum"}))
```
### 5. Export to Excel (ready for BOQ merge)
```python
qto.to_excel("IFC_QTO.xlsx", index=False)
```
### 6. Optional: validate IFC quality first
Use **BIMvision** or **Solibri Anywhere** (free viewers) to visually inspect the model and confirm that all **Pset\_ElementQuantity** properties are populated.
### 7. Handling federated models (multiple IFC files)
If the QRF supplies **several partial IFC files**, merge them once:
- **BIMvision → IFC Merge plugin** (permanent merge), or
- **IfcOpenShell** (memory merge) if you want to stay in Python.
### 8. When IFC lacks quantities
If the IFC only has geometry, compute **volume/length/area** yourself:
```python
import ifcopenshell.geom as geom
settings = geom.settings()
shape = geom.create_shape(settings, e)
volume = shape.geometry.volume
```
### 9. Keep the workflow **MVD-compliant**
The NBIMS QTO guide recommends exporting with the **CDB-2010 MVD** view (or later). Ask the designer to tick that option in Revit/ArchiCAD so that **Pset\_ElementQuantity** and **IfcMaterial** are automatically embedded.
### Summary of the integration pattern
This external-mode approach keeps your Python stack lightweight, avoids STAAD-Pro geometry duplication, and produces **code-compliant QTO tables** in minutes