Weight reference catalog
The initial catalog uses median weights from the supplied NTNU Norway post-consumer datasets. A source component stores the catalog version, category, recommended median weight, and sample provenance used when the production was recorded. Later catalog updates apply to new calculations; saved component snapshots preserve the original inputs.
Garment medians come from 16,464 garments weighed in 2025. Household textile values come from a separate 2,329-item sample, and socks are based on 816 individually weighed single socks. The source workbook recommends the median because a few heavy items can pull up the mean. Samples below 10 items are marked indicative. The garment dataset is CC BY-SA 4.0; the household-textile dataset is CC BY 4.0.
Formulas
Textile reused per finished piece: sum of (source-item median weight in grams × items used × utilization percentage) ÷ 100,000.
Textile reused for the production: textile reused per piece × identical units produced. This is based only on source materials; finished-piece weight is excluded.
Finished-piece mass for the production: finished-piece weight in grams × identical units produced ÷ 1,000.
Estimated avoided CO₂e: finished-piece mass in kg × 22.3 kg CO₂e per kg finished piece.
Estimated avoided water footprint: finished-piece mass in kg × 23,800 L per kg finished piece.
Example: a 140 g source T-shirt at 50% utilization contributes 0.070 kg textile reused per piece, or 0.840 kg for 12 pieces. If each finished piece weighs 182 g, finished-piece mass for the production is 2.184 kg; that gives 48.70 kg CO₂e and 51,979 L of estimated water footprint using the factors above.
Older production snapshots without a recorded finished-piece weight retain their original source-material basis. New production calculations use the separate bases shown above.
How to read the comparisons
- Textile weight is compared with 23 kg checked suitcases.
- CO₂e is compared with car kilometres using 0.23 kg CO2e per reference unit.
- Water footprint is compared with 2,500,000 L Olympic swimming pools.
These comparisons provide scale only; they do not mean the production literally saves that exact resource or completes that exact trip.
Assumptions and limits
- The model assumes upcycling displaces new textile production. It does not apply a displacement rate, because the supplied FAQ says this is not established specifically for upcycling.
- The CO₂e factor is derived from JRC EU textile-production totals for 2008, published in 2014. It is an EU average, not garment-specific, and production-only.
- The water figure is a RIVED weighted estimate based on cotton and polyester production water footprints. It is footprint-equivalent, not physical water measured or saved, and depends on fibre and location assumptions.
- Reference weights describe used Norwegian post-consumer items collected in 2025. They may differ from new garments or materials in other regions.
- Catalog and methodology versions are stored with each production calculation. Editing the active version should not silently change a saved product's inputs or impact snapshot.
Sources
- Pettersen et al. (2026), Norway post-consumer garment data, Zenodo v1.1.
- Pettersen and Aarak (2026), household textiles and socks, Zenodo v1.0.
- European Commission JRC (2014), Environmental Improvement Potential of Textiles.
- Freitas, Zhang, and Mathews (2017), Water Footprint Assessment of Polyester and Viscose.
- German Environment Agency (2025), passenger transport emissions used for the car-distance comparison.
Factors and comparison references are stored as versioned data and should be revised when their evidence or assumptions change.