According the new RICS, “Recovered biomass is considered to contain sequestered biogenic carbon, just like virgin
biomass, transferred from the previous product system. It is not necessary to consider
whether the original biomass (in its first use) was sustainably sourced when considering this.
Therefore, when reused or recycled biomass is used in a building or infrastructure asset, the
sequestered carbon is treated in exactly the same way as sustainably sourced virgin timber
or biomass: as a removal of biogenic CO2 in modules A1–A3. At end of life, the sequestered
carbon is emitted or transferred to the next product system and is considered as an
emission of biogenic CO2, as with sustainably sourced virgin timber and biomass. Therefore,
recovered biomass has a biogenic carbon balance over the asset’s life cycle.” So I think that the better approach would be modelling virgin timber in Reference case, then cancelling out A4-A5 (in case that there are no transport and equipment impact due to the reuse of timber) in the Proposed design to show the benefits of reused timber compared to virgin timber.
