The choice of Measurement Boundary in M&V determines which energy flows and explanatory variables must be measured; this boundary often conditions the choice between Options A/B (equipment-level) and Option C (whole facility).

The boundary is the virtual envelope that isolates the M&V perimeter: narrow (equipment only) leads to Options A or B, while wide (whole building) leads to Option C. The choice depends on whether physical isolation is possible, the reporting granularity required, and the cost of instrumentation. The boundary MUST be explicitly documented in the M&V Plan.

Draw the boundary as a literal box on a site diagram — every measured cable and pipe crossing the box must appear in your meter list.