The RIBA Plan of Work and the WLCA system boundary describe the same project, but they do not cover the same ground. Stages 0–4 broadly correspond to modules A0–A3, stage 5 to A4–A5, and stages 6–7 to the B modules. Then the Plan of Work stops. Nothing in it corresponds to modules C or D. End of life and what lies beyond the system boundary have no stage, no deliverable and no fee scope — yet a compliant assessment has to forecast them from concept design onwards.

That gap is what this drawing is for. The first view puts the RIBA stages underneath the modules whose activities they describe, so the uncovered ground is visible rather than argued. The second view is the counterpart: not what a stage describes, but what you have to answer for at each stage — where every module, C and D included, is in scope from concept design, and only the firmness of the answer changes.

Open the diagram on its own page ↗

Sources and caveats

Module definitions and scope boundaries are from Whole life carbon assessment for the built environment, RICS professional standard, 2nd edition (effective July 2024), sections 2.1–2.2 and 5.1–5.5. The project-phase mapping follows Table 1 of that standard; data sources by phase follow Tables 7 and 8. Module structure derives from BS EN 15978 and BS EN 17472.

The four-level maturity shading in the second view is not a table in the standard. It is my reading of Tables 7 and 8 alongside normal practice, offered as a rule of thumb — procurement route, asset type and client requirements all move it. Module A0 is generally assumed negligible for buildings but can be significant for infrastructure and masterplans; B8 is optional for buildings. Stage 6 sits over one column because handover is a moment rather than a span, not because it corresponds to module B1.1.