---
name: embodied-carbon-estimate
description: Screening estimate of a building's embodied carbon (A1-A3 or the modules the factors cover) from quantities - an IFC takeoff, a bill of quantities or a budget - multiplied by emission factors the user supplies from EPDs, EC3 or a national database; ranks the hotspots, compares material alternatives and lists what could not be matched. Use when the user asks about embodied carbon, "huella de carbono de la obra", "carbono incorporado", EPDs, low-carbon concrete options, or carbon targets for a design.
---

# Embodied carbon estimate

## Inputs
- Quantities by material with units: the CSV from `ifc-quantity-takeoff`, a BoQ, or the budget (APU quantities).
- Emission factors from the user's sources: product EPDs (best), EC3 from Building Transparency (has an API with an account), the ICE database, or a national database. One row per material: `material,factor,unit,stage,source[,density_kg_m3]`.
- Gross floor area if the user wants kg CO2e/m2.

## Procedure
1. Map each quantity line to a material name that exists in the factors file. Keep a mapping table so the user can review it.
2. If factors are missing, ask for them or show where to find them (EPD of the actual product, EC3 category baseline, national database). Do not fill them in from memory, even "typical" values.
3. Check the basis: same life-cycle modules for all factors (usually A1-A3), same declared unit, densities where m3 must become kg.
4. Run `python scripts/carbon.py quantities.csv factors.csv --gfa <m2>` and, for options, `--alt alternatives.csv` (material -> alternative material, both in the factors file).
5. Report the Pareto: usually two or three materials (concrete, steel, masonry or glazing) explain most of the total. Propose reduction levers for those only: mix design and cement replacement, less material by design, recycled content, a different system; each with the factor source that backs it.
6. List the gaps (no factor, unit mismatch) and the modules not covered.

## Output
- `carbon.md` (total, intensity, Pareto by material and group, scenario, gaps, sources) and `carbon.csv` (line by line).

## Never
- Never use an emission factor that the user did not provide or approve; every factor shows its source.
- Never sum factors that cover different life-cycle modules without saying so.
- Never call the result a certified LCA or a compliance result; it is a screening for decisions.