epd-compare

# /epd-compare — EPD Comparator Compare 2 or more products side-by-side on environmental impact metrics. Validates comparability (declared units, system boundaries, PCR alignment), generates comparison tables with percentage deltas, and checks LEED v4.1 MRc2 eligibility. This skill **reads** from the EPD Google Sheet but does **not write** to it. Output is a markdown comparison report. ## Input The user provides EPD data in one of these ways: 1. **Sheet row references** — "compare rows 5, 8, and 12" from the EPD Google Sheet 2. **Inline data** — pasted product names with GWP values 3. **File path** — a CSV or markdown file with EPD data 4. **From prior skills** — "compare the EPDs I just parsed/found" (uses data from the current conversation) 5. **Mixed** — "compare this PDF I just parsed against what's in the sheet" If the user doesn't specify a source, ask: **"Where is the EPD data? Sheet rows, pasted values, or from earlier in this conversation?"** ## Workflow ### Step 1: Collect data Gather EPD data from the specified source. For each product, you need at minimum: - Product name and manufacturer - GWP (A1-A3) value - Declared unit Additional fields improve the comparison: ODP, AP, EP, POCP, energy use, water use, system boundary, PCR, validity dates, LEED eligibility. ### Step 2: Validate comparability Before comparing, run these checks and report findings: **Declared unit alignment:** - Are all products using the same declared unit (e.g., all per m3, all pe...