Module D1 covers the potential carbon loads (costs) and benefits beyond the system boundary from any recovery of material arising from the construction (A4–A5), use (B2–B5) or end of life (C1–C4) stages.
Module D2 covers the potential carbon benefits beyond the system boundary of any utilities exported from the asset during use stages B6–B8, such as generated electricity or treated water.
Note that there is still some debate on and inconsistency with the calculation of the benefits and loads of Module D. Therefore, it is important to critically evaluate any savings derived from this module.