How CadranZero calculates, and what that is worth

A footprint figure is worth only the method that produces it and the sources it cites. This page describes both, including where they stop.

Two calculations, two frameworks

A product's footprint and a company's footprint are not calculated the same way, and confusing the two is the most common mistake.

For a product, life cycle assessment follows the methodological framework of ISO 14040, which sets the principles, and ISO 14044, which sets the requirements. The result is expressed in kgCO₂e per functional unit, for example one watch case.

For a company, the inventory follows the GHG Protocol: direct emissions (scope 1), those of purchased energy (scope 2), and the fifteen value chain categories (scope 3).

A single indicator, and we say so

What the platform produces is a carbon footprint within the meaning of ISO 14067: a single indicator, climate change. It is not a multi-criteria LCA, which would also measure water, acidification, ecotoxicity or land use.

The distinction matters, because a product can well improve its carbon footprint while degrading another indicator. We would rather say what we measure than let it be assumed we measure everything.

In the same way, no assessment produced here is « certified »: an LCA becomes so only through a critical review by an independent third party, which the platform neither performs nor claims to perform.

The six life cycle stages

Every line of an assessment belongs to one of these six stages, which lets two products be compared on the same breakdown:

  1. Materials: extraction and production of incoming materials, offcuts included.
  2. Manufacturing: workshop processes, and the energy they consume.
  3. Upstream transport: bringing materials and components to the site.
  4. Distribution: packaging and delivery to the customer.
  5. Use: what the product consumes during its life, if it consumes anything.
  6. End of life: treatment, recycling or disposal.

A high total on one stage is not a flaw, it is a lever: it shows where an effort will have effect.

Where the emission factors come from

An emission factor converts a physical quantity, a kilogram of steel or a kilowatt-hour, into kilograms of CO₂ equivalent. That is where a calculation's credibility is decided, and it is why the platform invents none.

  • BAFU-2025 (ecoinvent): 11,558 factors, the Swiss reference, labels in English.
  • Base Carbone (ADEME): 15,396 factors, the French reference, labels in French.

Every line of an assessment cites the factor chosen, its source database and its reference location. It is this traceability that lets you defend a figure before an auditor, rather than merely assert it.

A missing factor can be created to measure, provided its source is documented. A home-made factor without documentation is an opinion dressed as a measurement.

What is shared, and in how much detail

An assessment is worked on as a draft, finalised, then published. Until it is published, no one but its author sees it. Successive versions are kept with their date and author.

Sharing is then set part by part and house by house, at four levels: nothing, the figure alone, the breakdown by stage, or the full calculation register. The last level requires explicit confirmation, and any share can be revoked.

The limits, since there are some

An assessment rests on data someone entered. When a value is missing, a proxy is used, that is a neighbouring factor deemed representative: an approximation openly assumed, not a measurement.

The factors themselves carry an uncertainty, which comes from their source database and which we do not reduce. Two assessments run on different databases can differ without either being wrong.

Finally, an assessment ages. Beyond three years it remains real data but deserves revalidation: a process changes, an energy supplier changes, a site relocates.

These limits belong to the exercise itself, not to this tool. Passing over them would give a more comfortable and less defensible figure.

The reference texts

  • ISO 14040: principles and framework for life cycle assessment.
  • ISO 14044: requirements and guidelines.
  • ISO 14067: carbon footprint of products, a single indicator.
  • GHG Protocol Corporate Standard, and its value chain chapter for scope 3.
  • ADEME's Base Carbone, and the Swiss federal administration's LCI database (BAFU, ecoinvent data).

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Further reading: the life cycle assessment guide · the emission factors guide · consolidating a scope 3.1 · the tools given to suppliers · security and hosting