Carbon footprint and recycling: estimating avoided emissions

Key takeaway: Recycling reduces emissions because it avoids producing material from scratch, but those avoided emissions are not subtracted from your greenhouse gas inventory; they are reported separately. To estimate them you need actual tonnage by material, emission factors from recognized sources, a clear baseline scenario and a documented method.

Few sustainability topics generate as much confusion as recycling avoided emissions. Some companies subtract recycled tonnage from their inventory, others publish CO₂ savings without explaining where they come from, and others report nothing for fear of getting it wrong. All three have a cost: the first fails review, the second erodes credibility and the third wastes a real achievement.

For multinationals with plants in Mexico, there's an added layer: site data has to roll up into a group inventory, often against targets set by headquarters. This article explains the conceptual framework: where waste appears in a GHG Protocol inventory, what avoided emissions are and how to estimate them with a method you can defend. It doesn't include emission factors, because they depend on material, region, year and the source you choose.

Two different questions: your inventory and your avoided emissions

Before calculating anything, separate two questions that are often blended:

1. How much does my company emit? That's the corporate inventory. It measures emissions that occur, directly or indirectly, because of your activities.
2. How much was not emitted thanks to what we did? That's an avoided-emissions estimate. It compares what happened with a hypothetical scenario in which you didn't recycle.

The GHG Protocol is explicit: avoided emissions from recycling are not included in or deducted from the Scope 3 inventory. They may be reported separately, with their methodology. Mixing the two figures is the most common error and the easiest for a reviewer to spot.

Where waste sits in GHG Protocol scopes

For Scope 2 in Mexico, the location-based method uses the national grid emission factor published annually by Mexican authorities; if a supply contract provides specific data, the market-based method can be reported as well. Make sure your group uses the Mexican factor for Mexican sites rather than a default from another country.

Category 5 treats recycling in a particular way. Under the recycled content approach described in the Scope 3 technical guidance, emissions from the recycling process are allocated to whoever uses the recycled material as an input. For the waste generator, the relevant piece is usually transport to the recycling facility. Waste sent to landfill, by contrast, carries its disposal emissions. That's why diverting material from landfill already improves your inventory, with nothing subtracted. Always check the current version of the guidance when defining your method.

The logic of an avoided-emissions estimate

Conceptually, for each material:

Avoided emissions = tons recycled × (baseline scenario emissions − recycling scenario emissions)

The baseline usually combines two things: the emissions from disposing of the waste and the emissions from producing the same amount of material from virgin resources. The recycling scenario includes transport, sorting and reprocessing.

The substitution factor is the one most often forgotten. Not every recovered ton replaces a ton of virgin material: there are process losses and, for some plastics, recycled material goes into less demanding applications.

Why some materials dominate the result

The benefit depends on how much energy and how many emissions it takes to make the material from scratch, which is why metals usually dominate. Recycling aluminum saves roughly 95% of the energy needed to produce it from bauxite, and recycling copper saves around 85%. For background, see why aluminum recycling saves so much energy.

Keep in mind that an energy saving doesn't translate automatically into the same percentage of emissions saved, because that depends on the energy source. Use emission factors, not energy percentages, for your final numbers.

How to choose emission factors

There's no single correct factor, but there are criteria for choosing well:

• Geography: prefer factors reflecting the region where the displaced production occurs. Tools such as the U.S. Environmental Protection Agency's WARM model are a useful reference, but they reflect U.S. conditions.
• Year and version: record the exact database version you used.
• Comparable boundaries: compare primary and recycled production using the same system boundaries.
• Consistency: use the same source year after year, or restate the series if you switch.
• Specific data where available: verifiable data from your recycler or the material's end user beats averages.

A step-by-step first estimate

1. Define the purpose. Is it for an ESG report, a customer request or internal communication? That sets the level of rigor.
2. Gather actual tons by material, from the same dataset you use for your recycling ESG metrics.
3. Describe the baseline scenario in one sentence anyone can follow.
4. Select and document factors with source, year and assumptions.
5. Calculate by material, not with one average factor for everything.
6. Present a range rather than a falsely precise number when assumptions are uncertain.
7. Report separately from the inventory, with a short methodology note.

Also avoid claiming the same avoided emissions your recycler or the material's buyer claims without making clear it's the same benefit seen from different points in the chain. Marketing teams at headquarters should apply the same caution before turning the figure into a public claim.

How Zikloa can help

The first input of any serious estimate is actual weight by material. Zikloa collects and recycles aluminum, copper, ferrous scrap, plastics, cardboard and paper in Nuevo León and Mexico City, with certified-scale weighing and documentation for every service, giving your team a solid base for emissions estimates. See how we handle one of the highest-impact materials on our aluminum recycling page.

If you want your recycling data ready for your next carbon footprint exercise, contact our team.