Verified Carbon Unit (VCU) Verified Carbon Units (VCUs) are carbon emission reduction units issued by the VCS. These offsets must be real, the abatement must have occurred previous to issuance, they must be additional by going beyond business-as-usual activities, be measurable, permanent, not temporarily displace emissions, and the findings need to be independently verified and unique so they cannot be used more than once to offset emissions. Verified Carbon Standard Valuation Vocabulary