The formula
CO₂ avoided = Σ (kilos of each material × its factor)
Where it comes from
Recycling avoids emissions two ways: no virgin material has to be extracted and processed, and nothing is buried that would emit in landfill. The gap between materials is huge and very unintuitive. Aluminium is the extreme case: making it from bauxite means electrolysis, which is pure electricity, while remelting a can costs a fraction of that energy. That is why half a kilo of cans avoids more CO₂ than ten kilos of glass, even though glass fills twenty times the bin. Seeing the order by CO₂ rather than by weight is what changes how you sort.
How to work it out by hand
- Write down the kilos of each material you recycle in a normal week
- Multiply each one by its CO₂ avoided per kilo
- Add the seven: that is one week’s saving
- Multiply by the weeks of the period you want to count
What is worth knowing
The factors are life-cycle averages published by the US Environmental Protection Agency (WARM) and the UK government, comparing recycling against landfill. They are not measurements of your plant or your country: they shift with the electricity that feeds the facility and with transport distance. They are good for ranking materials and seeing orders of magnitude, not for certifying a footprint.