
bim-cost-estimation-cwicr
Automated cost estimation from BIM models using DDC CWICR database (8 national bases, 78,228 positions). AI classification + vector search for accurate pricing.
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npx skills add https://github.com/datadrivenconstruction/ddc_skills_for_ai_agents_in_construction --skill bim-cost-estimation-cwicr- 01
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Run the command in your project. The CLI asks which agents to install for.
- 02
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- 03
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The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
BIM Cost Estimation with DDC CWICR
Generate accurate cost estimates from BIM models using AI classification and the DDC CWICR construction cost database.
Business Case
Problem: Traditional cost estimation:
- Manual and time-consuming (weeks for detailed estimate)
- Subjective and inconsistent between estimators
- Requires specialized knowledge
- Difficult to update with design changes
Solution: Automated BIM-to-cost pipeline:
- Extract quantities directly from model
- AI classifies elements to work items
- Vector search finds matching prices in CWICR
- Complete estimate in hours, not weeks
ROI: 80% reduction in estimation time, consistent methodology
System Architecture
┌──────────────────────────────────────────────────────────────────────────┐
│ BIM TO COST ESTIMATION PIPELINE │
├──────────────────────────────────────────────────────────────────────────┤
│ │
│ ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────────────┐ │
│ │ BIM │ │ DDC │ │ AI │ │ DDC CWICR │ │
│ │ Model │────►│Converter│────►│ LLM │────►│ Vector Search │ │
│ │.rvt/.ifc│ │ │ │ │ │ (Qdrant) │ │
│ └─────────┘ └─────────┘ └─────────┘ └─────────────────┘ │
│ │ │ │ │
│ ▼ ▼ ▼ │
│ ┌─────────┐ ┌─────────┐ ┌──────────┐ │
│ │ .xlsx │ │ Work │ │ Matched │ │
│ │ QTO │ │ Items │ │ Rates │ │
│ └─────────┘ └─────────┘ └──────────┘ │
│ │ │ │ │
│ └──────────────┼────────────────────┘ │
│ ▼ │
│ ┌─────────────────┐ │
│ │ COST ESTIMATE │ │
│ │ │ │
│ │ • By element │ │
│ │ • By trade │ │
│ │ • By phase │ │
│ │ • Resources │ │
│ └─────────────────┘ │
│ │
└──────────────────────────────────────────────────────────────────────────┘
DDC CWICR Database
Database Overview:
work_items: 78228 # 8 national bases
resources: 27,672
languages: 9 (AR, DE, EN, ES, FR, HI, PT, RU, ZH)
fields_per_item: 85
embedding_model: BAAI/bge-m3 (1024d)
vector_db: Qdrant
Collections:
- ddc_cwicr_ar # Arabic (Dubai prices)
- ddc_cwicr_de # German (Berlin prices)
- cwicr_en_v3 # English (Toronto prices)
- ddc_cwicr_es # Spanish (Barcelona prices)
- ddc_cwicr_fr # French (Paris prices)
- ddc_cwicr_hi # Hindi (Mumbai prices)
- ddc_cwicr_pt # Portuguese (São Paulo prices)
- ddc_cwicr_ru # Russian (St. Petersburg prices)
- ddc_cwicr_zh # Chinese (Shanghai prices)
Pipeline Stages
| Stage | Name | Description |
|---|---|---|
| 0 | Collect BIM Data | Extract elements from Revit/IFC |
| 1 | Project Detection | AI identifies project type |
| 2 | Phase Generation | AI creates construction phases |
| 3 | Element Assignment | AI maps types to phases |
| 4 | Work Decomposition | AI breaks types into work items |
| 5 | Vector Search | Find matching rates in CWICR |
| 6 | Unit Mapping | Convert BIM units to rate units |
| 7 | Cost Calculation | Qty × Unit Price |
| 7.5 | Validation | CTO review for completeness |
| 8 | Aggregation | Sum by phases and categories |
| 9 | Report Generation | HTML and Excel outputs |
Python Implementation
import pandas as pd
import numpy as np
from qdrant_client import QdrantClient
from qdrant_client.models import Filter, FieldCondition, MatchValue
from openai import OpenAI
from typing import List, Dict, Optional
from dataclasses import dataclass
import json
@dataclass
class WorkItem:
"""Matched work item from CWICR"""
cwicr_code: str
description: str
unit: str
unit_price: float
labor_cost: float
material_cost: float
equipment_cost: float
productivity: float # units per hour
currency: str
confidence: float
@dataclass
class CostLineItem:
"""Single line item in estimate"""
bim_type: str
work_item: WorkItem
quantity: float
quantity_unit: str
total_cost: float
labor_cost: float
material_cost: float
equipment_cost: float
phase: str
trade: str
class BIMCostEstimator:
"""BIM to cost estimation using DDC CWICR"""
def __init__(
self,
qdrant_url: str,
qdrant_api_key: str = None,
openai_api_key: str = None,
language: str = "EN"
):
self.qdrant = QdrantClient(url=qdrant_url, api_key=qdrant_api_key)
self.openai = OpenAI(api_key=openai_api_key)
self.language = language
self.collection = f"ddc_cwicr_{language.lower()}"
def get_embedding(self, text: str) -> List[float]:
"""Generate embedding for text"""
response = self.openai.embeddings.create(
model="BAAI/bge-m3",
input=text,
dimensions=1024
)
return response.data[0].embedding
def search_cwicr(
self,
query: str,
limit: int = 5,
category_filter: str = None
) -> List[WorkItem]:
"""Search CWICR database for matching work items"""
# Get embedding
query_vector = self.get_embedding(query)
# Build filter if category specified
query_filter = None
if category_filter:
query_filter = Filter(
must=[
FieldCondition(
key="category",
match=MatchValue(value=category_filter)
)
]
)
# Search
results = self.qdrant.search(
collection_name=self.collection,
query_vector=query_vector,
query_filter=query_filter,
limit=limit
)
# Parse results
work_items = []
for r in results:
payload = r.payload
work_items.append(WorkItem(
cwicr_code=payload.get('code', ''),
description=payload.get('description', ''),
unit=payload.get('unit', ''),
unit_price=float(payload.get('unit_price', 0)),
labor_cost=float(payload.get('labor_cost', 0)),
material_cost=float(payload.get('material_cost', 0)),
equipment_cost=float(payload.get('equipment_cost', 0)),
productivity=float(payload.get('productivity', 1)),
currency=payload.get('currency', 'USD'),
confidence=r.score
))
return work_items
def decompose_bim_type(
self,
bim_type: str,
category: str
) -> List[str]:
"""Use LLM to decompose BIM type into work items"""
prompt = f"""
Decompose this BIM element type into construction work items:
BIM Type: {bim_type}
Category: {category}
List the individual work activities needed to construct this element.
For example, "Brick Wall 240mm" decomposes into:
- Masonry: Brick laying
- Mortar: Cement mortar for joints
- Plaster: Internal plaster finish
- Paint: Wall painting
Return a JSON array of work item descriptions.
Example: ["Brick masonry laying", "Cement mortar for brick joints", "Internal cement plaster 15mm"]
"""
response = self.openai.chat.completions.create(
model="gpt-4o",
messages=[{"role": "user", "content": prompt}],
response_format={"type": "json_object"}
)
try:
result = json.loads(response.choices[0].message.content)
return result.get('work_items', [bim_type])
except:
return [bim_type]
def estimate_element(
self,
bim_type: str,
category: str,
quantity: float,
quantity_unit: str,
phase: str = "Construction"
) -> List[CostLineItem]:
"""Estimate cost for single BIM element type"""
# Decompose into work items
work_descriptions = self.decompose_bim_type(bim_type, category)
line_items = []
for work_desc in work_descriptions:
# Search CWICR for matching rate
matches = self.search_cwicr(work_desc, limit=1)
if not matches:
continue
best_match = matches[0]
# Convert quantity if units don't match
adjusted_qty = self._convert_units(
quantity, quantity_unit, best_match.unit
)
# Calculate costs
total = adjusted_qty * best_match.unit_price
labor = adjusted_qty * best_match.labor_cost
material = adjusted_qty * best_match.material_cost
equipment = adjusted_qty * best_match.equipment_cost
line_items.append(CostLineItem(
bim_type=bim_type,
work_item=best_match,
quantity=adjusted_qty,
quantity_unit=best_match.unit,
total_cost=total,
labor_cost=labor,
material_cost=material,
equipment_cost=equipment,
phase=phase,
trade=self._get_trade(category)
))
return line_items
def estimate_from_qto(
self,
qto_data: pd.DataFrame,
type_column: str = "Type Name",
category_column: str = "Category",
quantity_column: str = "Volume"
) -> List[CostLineItem]:
"""Generate estimate from QTO DataFrame"""
all_line_items = []
# Group by type
grouped = qto_data.groupby([category_column, type_column]).agg({
quantity_column: 'sum'
}).reset_index()
for _, row in grouped.iterrows():
items = self.estimate_element(
bim_type=row[type_column],
category=row[category_column],
quantity=row[quantity_column],
quantity_unit="m³" # Assume volume, adjust based on category
)
all_line_items.extend(items)
return all_line_items
def _convert_units(
self,
value: float,
from_unit: str,
to_unit: str
) -> float:
"""Convert between units"""
# Simplified conversion - expand as needed
conversions = {
('m³', 'm³'): 1.0,
('m²', 'm²'): 1.0,
('m', 'm'): 1.0,
('ft³', 'm³'): 0.0283168,
('ft²', 'm²'): 0.092903,
('ft', 'm'): 0.3048,
}
key = (from_unit.lower(), to_unit.lower())
factor = conversions.get(key, 1.0)
return value * factor
def _get_trade(self, category: str) -> str:
"""Map BIM category to trade"""
trade_map = {
'Walls': 'Masonry',
'Floors': 'Concrete',
'Structural Columns': 'Concrete',
'Structural Framing': 'Steel',
'Doors': 'Carpentry',
'Windows': 'Glazing',
'Plumbing Fixtures': 'Plumbing',
'Electrical Equipment': 'Electrical',
'Mechanical Equipment': 'HVAC'
}
return trade_map.get(category, 'General')
def generate_estimate_report(
self,
line_items: List[CostLineItem],
project_name: str,
output_path: str
) -> dict:
"""Generate comprehensive estimate report"""
# Convert to DataFrame
records = []
for item in line_items:
records.append({
'BIM Type': item.bim_type,
'Work Item': item.work_item.description,
'CWICR Code': item.work_item.cwicr_code,
'Quantity': round(item.quantity, 2),
'Unit': item.quantity_unit,
'Unit Price': round(item.work_item.unit_price, 2),
'Labor': round(item.labor_cost, 2),
'Material': round(item.material_cost, 2),
'Equipment': round(item.equipment_cost, 2),
'Total': round(item.total_cost, 2),
'Phase': item.phase,
'Trade': item.trade,
'Currency': item.work_item.currency,
'Confidence': round(item.work_item.confidence, 2)
})
df = pd.DataFrame(records)
# Calculate totals
total_cost = df['Total'].sum()
total_labor = df['Labor'].sum()
total_material = df['Material'].sum()
total_equipment = df['Equipment'].sum()
# Summary by trade
by_trade = df.groupby('Trade')['Total'].sum().sort_values(ascending=False)
# Write Excel
excel_path = f"{output_path}/{project_name}_Estimate.xlsx"
with pd.ExcelWriter(excel_path, engine='openpyxl') as writer:
# Summary sheet
summary_data = {
'Metric': ['Total Cost', 'Labor Cost', 'Material Cost', 'Equipment Cost'],
'Value': [total_cost, total_labor, total_material, total_equipment]
}
pd.DataFrame(summary_data).to_excel(writer, sheet_name='Summary', index=False)
# By Trade
by_trade.to_frame().to_excel(writer, sheet_name='By Trade')
# Detail
df.to_excel(writer, sheet_name='Detail', index=False)
return {
'excel_path': excel_path,
'total_cost': total_cost,
'total_labor': total_labor,
'total_material': total_material,
'total_equipment': total_equipment,
'by_trade': by_trade.to_dict(),
'line_items': len(df),
'currency': line_items[0].work_item.currency if line_items else 'USD'
}
# Usage Example
def estimate_from_bim_model(
model_path: str,
qdrant_url: str,
language: str = "EN",
output_dir: str = "."
) -> dict:
"""Complete BIM to cost estimation workflow"""
import subprocess
from pathlib import Path
# Step 1: Convert BIM to Excel
print("Converting BIM model...")
subprocess.run([
r"C:\DDC\RvtExporter.exe",
model_path,
"complete", "bbox"
])
xlsx_path = Path(model_path).with_suffix('.xlsx')
# Step 2: Load QTO data
print("Loading quantity data...")
df = pd.read_excel(xlsx_path)
# Step 3: Initialize estimator
estimator = BIMCostEstimator(
qdrant_url=qdrant_url,
language=language
)
# Step 4: Generate estimate
print("Generating cost estimate...")
line_items = estimator.estimate_from_qto(df)
# Step 5: Generate report
project_name = Path(model_path).stem
result = estimator.generate_estimate_report(
line_items=line_items,
project_name=project_name,
output_path=output_dir
)
print(f"\nEstimate Complete!")
print(f"Total Cost: {result['currency']} {result['total_cost']:,.2f}")
print(f"Excel Report: {result['excel_path']}")
return result
if __name__ == "__main__":
result = estimate_from_bim_model(
model_path=r"C:\Projects\Building.rvt",
qdrant_url="https://your-qdrant-instance.io",
language="DE",
output_dir=r"C:\Projects\Estimates"
)
n8n Workflow
See: n8n_4_CAD_(BIM)_Cost_Estimation_Pipeline_4D_5D_with_DDC_CWICR.json
stages:
- convert: RvtExporter → XLSX
- detect_project: LLM identifies project type
- generate_phases: LLM creates construction phases
- decompose: LLM breaks types into work items
- vector_search: Qdrant finds CWICR matches
- calculate: Qty × Unit Price
- validate: CTO review
- report: HTML + Excel output
Output Example
╔══════════════════════════════════════════════════════════════╗
║ COST ESTIMATE SUMMARY ║
║ Project: Office Building Berlin ║
║ Date: 2026-01-24 ║
╠══════════════════════════════════════════════════════════════╣
TOTAL PROJECT COST: EUR 4,523,678.00
───────────────────────────────────────────────────────────────
Labor: EUR 1,847,234.00 (41%)
Materials: EUR 2,312,456.00 (51%)
Equipment: EUR 363,988.00 ( 8%)
BY TRADE
───────────────────────────────────────────────────────────────
Concrete: EUR 1,234,567.00 (27%)
Masonry: EUR 876,543.00 (19%)
Steel Structure: EUR 654,321.00 (14%)
MEP: EUR 543,210.00 (12%)
Finishes: EUR 432,109.00 (10%)
Other: EUR 782,928.00 (18%)
CONFIDENCE ANALYSIS
───────────────────────────────────────────────────────────────
High (>0.85): 78%
Medium (0.70-0.85): 18%
Low (<0.70): 4%
╚══════════════════════════════════════════════════════════════╝
Resources
- CWICR Repository: https://github.com/datadrivenconstruction/OpenConstructionEstimate-DDC-CWICR
- Live Demo: https://openconstructionestimate.com
- Qdrant: https://qdrant.tech
"Resource-based costing separates physical quantities from volatile prices, enabling transparent and auditable estimates."
FAQ
What does the bim-cost-estimation-cwicr skill do?
Automated cost estimation from BIM models using DDC CWICR database (8 national bases, 78,228 positions). AI classification + vector search for accurate pricing.
How do I install bim-cost-estimation-cwicr?
Run npx skills add https://github.com/datadrivenconstruction/ddc_skills_for_ai_agents_in_construction --skill bim-cost-estimation-cwicr in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/bim-cost-estimation-cwicr/ (personal) or .claude/skills/bim-cost-estimation-cwicr/ (project).
Which AI agents can use bim-cost-estimation-cwicr?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is bim-cost-estimation-cwicr safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains bim-cost-estimation-cwicr?
It is published by datadrivenconstruction in datadrivenconstruction/ddc_skills_for_ai_agents_in_construction. It has 133 recorded installs.
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