Lifecycle decisions
Use system boundaries and sensitivity checks to compare improvement options.
Frame the comparison
State the service delivered and the alternatives under consideration. Use a consistent functional unit and describe the time period. An attractive material substitution can change impacts elsewhere in the system.
Test the assumptions
Review lifetime, transport distance, energy supply and recovery yield. Identify which assumptions can reverse the comparison. Prioritize better data where it matters to the decision.
Explain the trade-offs
Present the result alongside uncertainty and implementation requirements. Separate measured findings from a recommended next action. A useful assessment makes the choice clearer without concealing its limitations.