Estimate Construction Costs from Revit/IFC Models with GPT-4 and Claude

Estimate material price and total cost for grouped BIM/CAD elements using an LLM-driven analysis. The workflow accepts an existing XLSX (from your model) or, if missing, can trigger a local RvtExporter.exe to generate one. It enriches each element group with quantities, pricing, confidence, and produces a multi-sheet Excel report plus a polished HTML executive report.

What it does

• Reads grouped element data (from XLSX or extracted via RvtExporter.exe).
• Builds enhanced prompts with clear rules (volumes/areas are already aggregated per group).
• Calls your selected LLM (OpenAI/Anthropic/etc.) to identify materials, pick the pricing unit, and estimate price per unit and total cost.
• Parses AI output, adds per-group KPIs (cost %, rank), and aggregates project totals (by material, by category).
• Exports a multi-sheet XLSX and an HTML executive report (charts, KPIs, top groups).

Prerequisites

• LLM credentials for your chosen provider (e.g., OpenAI, Anthropic). Enable exactly one chat node and connect credentials.
• Windows host only if you want to auto-extract from .rvt/.ifc via RvtExporter.exe. If you already have an XLSX, Windows is not required.
• Optional: Internet access on the LLM side for price lookups (model/tooling dependent).

How to use

1. Import this JSON into n8n.
2. Open the Setup node(s) and set:
   • project_file — path to your .rvt/.ifc or to an existing grouped *_rvt.xlsx
   • path_to_converter — C:\\DDC_Converter_Revit\\datadrivenlibs\\RvtExporter.exe (optional)
   • country — used to guide price sources/standards (e.g., Germany)
3. In the canvas, enable one LLM node (e.g., OpenAI or Anthropic) and connect credentials; keep others disabled.
4. Execute workflow (Manual Trigger). It will detect/build the XLSX, run analysis, then write the Excel and open the HTML report.

Outputs

• Excel: Price_Estimation_Report_YYYY-MM-DD.xlsx with sheets:
  • Summary, Detailed Elements, Material Summary, Top 10 Groups
• HTML: executive report with charts (project totals, top materials, top groups).
• Per-group fields include: Material (EU/DE/US), Quantity & Unit, Price per Unit (EUR), Total Cost (EUR), Assumptions, Confidence.

Notes & tips

• Quantities in the input are already aggregated per group — do not multiply by element count.
• If you prefer XLSX-only extraction, run your converter with a -no-collada flag upstream.
• Keep ASCII-safe paths and ensure write permissions to the output folder.

Categories

Data Extraction · Files & Storage · ETL · CAD/BIM · Cost Estimation

Tags

cad-bim, price-estimation, cost, revit, ifc, xlsx, html-report, llm, materials, qto

Author

DataDrivenConstruction.io
[email protected]

Consulting and Training

We work with leading construction, engineering, consulting agencies and technology firms around the world to help them implement open data principles, automate CAD/BIM processing and build robust ETL pipelines.

If you would like to test this solution with your own data, or are interested in adapting the workflow to real project tasks, feel free to contact us.

Docs & Issues:
Full Readme on GitHub