This part of the M&V Plan can't be very detailed since you do not yet know what needs to be done. What you will do depends upon the issues uncovered. In general the action plan simply identifies what you will do when deviations occur between the projected savings and the actual savings. Typically this involves identifying additional energy saving strategies in the facility and using the calibrated model, for example, to determine additional energy savings. The cost and savings of the additional energy saving measures should be summarized in the final M&V report. It's a good idea to indicate that the owner will be responsible for implementing these recommendations as budget and time allow.