HERS raters are special inspectors certified by the California Energy Commission (CEC) to rate homes according to the Home Energy Rating System (HERS). A HERS rater is trained to perform independent (“third-party”) energy efficiency field verifications and/or diagnostic tests to determine energy efficiency levels. A HERS rater must be independent and cannot have any financial involvement with the project as it would be a conflict of interest. While HVAC contractors should test their own work, a HERS rater is required by the California building code to verify the contractor’s work and provide official documentation to city inspectors. HERS raters work in conjunction with local building departments who are required to obtain special documents, technically named “CF-3R” forms, signed by a certified HERS rater before issuing final approval and a certificate of occupancy (CO).