For an empty-return impact calculation, define both the attributed movement and the units in its denominator.

Evidence file

  • Return type
  • Attributed distance
  • Empty units returned
  • Calculation period

Keep uncertainty visible

Separate dedicated collection from added movement on a shared route. Confirm that denominator, period and system boundary match.

Condition where the result is valid

Report impact per empty container returned. Recalculate if the allocation rule changes.