Methodology for Net Avoided Emissions

The analysis calculates net avoided emissions resulting from secondhand transactions across SMG’s General Marketplaces – Ricardo, tutti.ch, and anibis.ch – from 1 January 2025 to 31 December 2025.

Calculation Logic

SMG determines avoided emissions using the following logic:

Net avoided emissions

= (alternative scenario emissions × replacement rate (%))

− emissions generated by secondhand transactions

Consequential Life Cycle Assessment Approach

The estimation uses the consequential life cycle assessment method, aligned with internationally recognised guidance from the World Resources Institute. It combines actual marketplace activity data with survey input from buyers and sellers to assess how secondhand shopping displaces new purchases, and the amount of carbon it avoids.

The analysis incorporates three key components:

• Alternative scenario emissions:
  The full cradle-to-consumer footprint of a new product that would otherwise have been purchased. This includes emissions from raw material extraction, manufacturing, distribution, and final delivery.
• Replacement rate:
  The proportion of secondhand purchases that displace the purchase of a new product, based on user-reported behaviour. This metric varies by product category.
• Generated emissions from secondhand transactions:
  The carbon footprint associated with the secondhand exchange itself, including delivery emissions (e.g., post, local pickup), packaging emissions, and SMG’s operational emissions related to facilitating the transaction.

Boundaries and Exclusions

Transactions from professional sellers and businesses are excluded, as their activity is primarily commercially driven and does not reflect typical peer-to-peer secondhand behaviour underpinning the displacement assumption of the model.

In addition, certain product categories and types are excluded. Exclusions are applied systematically and include, but are not limited to, vehicles, tickets and vouchers, services, as well as unique or collectible items. Category allocations may evolve over time where classification is user-driven. No large-scale manual reclassification is performed in order to preserve dataset integrity and methodological consistency.

The same exclusion principles as in the previous reporting year have been applied. The full report including methodology is published in SMG’s 2024 Avoided Emissions Report.

Avoided emissions are disclosed separately from SMG’s Scope 1–3 GHG inventory and do not reduce or offset the reported emissions.

Net avoided emissions in 2025 were converted into an equivalent number of round-trip flights between Zurich and New York per individual passenger, using DEFRA-aligned emission factors.