I am interested in your take on the practical modelling of secondary material (SM) inputs and Material For Recycling (MFR) outputs when using the EN 15804 (GreenDelta implementation) system model of Ecoinvent.
The database (correctly) accounts for these indicators not only in the foreground system, but also in the background system. The result is that both indicators are likely not 0 even if my product contains no recycled material and is not sent for recycling at end-of-life.
My problem comes when modelling the net flow of materials leaving the product system (stages A-C) to be considered in module D. To account for processes in module D, the net flow (MFR minus SM, in kg) needs to be separated out for each material, but the indicator results from the life cycle inventory are aggregated. SM and MFR can thus both be a mix of e.g. iron scrap, aluminium scrap, waste cardboard, and there is no feasible way to model module D.
I cannot find any rules in the standard or PCR that would allow me to disregard from these flows just because they arise from the background system.
How have other LCA practitioners solved this? Are you tracking the use of "Recycled content cut-off" processes for each type of material and doing the net flow calculation manually? Are you manually changing names of elementary flows in the database to "SM (iron scrap"), etc., or are you simply disregarding the SM and MFR flows from the background system in your module D calculations?
I checked but this specific topic does not seem to have been addressed in the white paper Ciroth and Hamed (2025) Module D in Environmental Product Declarations (EPDs).
