The M&V provider writes the M&V plan, but if possible, involve the facility’s operational staff. The plan must provide the following (see a sample M&V plan in the Documentation Toolkit):

standard IPMVP language and terminology
which option or method from the document will be used
who will conduct the M&V program
assumptions about significant variables or unknowns
an accurate baseline using techniques appropriate to your project
the method of ensuring an accurate energy-savings determination 
a post-installation inspection plan
criteria for equipment metering, calibration, and measurement period
the level of accuracy to be achieved by all major components
quality assurance measures
the contents of reports to be prepared, along with a schedule.