If you have process wastes in A1-A3 that have a value associated with them and have reached the end-of-waste state, they can be considered as co-products.
For example, if the main product under study uses steel as a raw material that is cut to size during manufacturing, and the off-cuts are used in another product process or sold as scrap, co-product allocation may need to be applied, depending on the mass and price of the main product and the co-product.
If process subdivision isn't possible, allocation of co-products should be done using physical allocation or economic allocation, per EN 15804+A2, clause 6.4.3.2.
The calculator below can be used to decide which allocation method, if any, should be used for your product life cycle assessment, and what allocation percentage to apply. It splits one flow (a raw material, energy use, packaging or ancillary material, waste, or a direct emission) between your main product and up to three co-products. Run it once per flow you need to split. Only the blue cells are editable.
How to use the calculator
Choose the flow. In "the source that is allocated per product and co-products," pick what you're allocating (raw material, energy, waste, etc.) — this is just a label for your records.
Choose what it's proportional to. In "the source is proportional to," pick one of two options:
Output mass ratio — use this when the flow simply follows how much (by mass) of each product comes out of the process. This is the usual choice for raw materials.
'Source utilisation' ratio — use this when mass doesn't reflect how the flow is really shared, and you instead know (or can estimate) the percentage of that specific flow each product/co-product uses directly — e.g., 60% of the electricity, or 80% of the water. Typical for energy, water, direct emissions, or ancillary/packaging materials.
A red note then tells you to fill in Question #1 (if you chose mass ratio) or Question #2 (if you chose source utilisation) — the other question is ignored, so leave it as is.
Enter mass and revenue shares. For each co-product, enter its share of output mass and its share of revenue (main product is calculated for you). Both rows must total 100%.
Answer the active question.
Question #1 asks: does this flow apply to this co-product at all? Answer YES/NO for each co-product. Answer NO if the flow simply isn't relevant to it (e.g., a raw material that only goes into the main product) — that co-product is then dropped from the allocation entirely.
Question #2 asks: what percentage of this flow does each product/co-product actually use? Enter that percentage directly for the main product and each co-product (this is the same figure you estimated in step 2 for the source-utilisation option). Use 0% for a co-product the flow doesn't apply to.
Decide on the 1% rule. If a co-product is flagged "...but it can be neglected" (revenue share ≤1%), set "neglect the co-product allocation with the revenue =<1%" to YES to fold its share into the main product, or NO to keep it allocated by economic value.
Read the result. The "multiplication factor for the source" gives you a decimal for the main product and each co-product (all four add up to 1). This factor is the share of your total flow that belongs to that product — so if you know the total amount of the flow for the whole process, you multiply it by the factor to get that product's portion of it. For example, if the process uses 1,000 kg of a raw material in total and the calculator gives Co-Product #1 a factor of 0.15, then 1,000 × 0.15 = 150 kg of that raw material is attributed to Co-Product #1 (and you'd do the same for the main product and the other co-products with their own factors). This is the number you then use as that co-product's share of the input/output flow in your LCA calculation.
If you have any questions about using it, please don't hesitate to Contact Us.