In an alteration/addition project, when using the performance compliance approach, compliance credit may be claimed towards the addition when the work scope includes improvements to the efficiency of existing energy features.

In following with the performance compliance approach, the Energy Consultant performs compliance calculations (CF-1R) taking credit for intended improvements to existing conditions. The XML file from those calculations is exported from the compliance software and uploaded to a unique project in a HERS Provider’s Registry. Where the XML file indicates "existing conditions" for which credit is being claimed, the Registry generates an EXC-20 and marks the CF-1R as provisional until the EXC-20 has been verified.

Verification of existing conditions that will be improved on the EXC-20 must occur before construction begins. A registered (signed by the Rater) CF-3R-EXC-20-H will be required by the HERS Provider Registry as a prerequisite to validation of the "provisional" CF-1R. Once the EXC-20 has been certified by a HERS Rater, the associated CF-1R becomes valid and may be submitted to the building department as part of the permit application.

In practice the Energy Consultant could have a HERS Rater verify a "laundry list" of existing conditions before any compliance calculations are performed. Then the compliance calculations would be performed with select items off that list, the compliance calculations uploaded to the Registry and the EXC-20 generated by the Registry. In this way, the Rater only needs to confirm that all of the items listed on the EXC-20 were verified during the original site visit.