Pick a period and a boundary
Choose a recent twelve-month period and decide which sites, entities and activities are in scope. Write the boundary down; it will be needed again.
Gather the activity data you already have
Utility bills, fuel purchases, travel records and purchasing data are a sufficient starting point. Note whether each figure is metered, invoiced or estimated.
Be explicit about gaps
A baseline with documented estimates is more useful than one that quietly hides them. Gaps become your data-improvement list for the following year.
Review before you rely on it
Have someone outside the data collection process review the totals for obvious errors before targets are set against them.
General educational content, not professional, legal or regulatory advice. — Carbover editorial