Based on the principles of Earned Value Management (EVM) found in the PMBOK® Guide, the Cost Variance (CV) is a measure of cost performance on a project.

Formula: $CV = EV - AC$

Calculation: Given the metrics:

Earned Value ($EV$) = $\$20,000$

Actual Cost ($AC$) = $\$22,000$

$CV = 20,000 - 22,000 = -2,000$

Interpretation:

A negative CV ($-2,000$ in this case) indicates that the project is over budget. It means the actual cost spent to date is higher than the value of the work performed.

A positive CV would indicate that the project is under budget.

A CV of zero would indicate that the project is exactly on budget.

Note: The Planned Value ($PV$) of $\$28,000$ is used for calculating Schedule Variance ($SV = EV - PV$), but it is not used in the calculation for Cost Variance.