Certified performance is an independent assessment of a home’s energy efficiency. The most common metric is a Home Energy Rating System (HERS) Index. The HERS score is similar to a miles-per-gallon (MPG) rating for cars helping homeowners and buyers compare homes in terms of energy efficiency. To determine the HERS score, a certified rater will conduct an in-depth energy performance assessment of a home using testing equipment, inspections, and the collection of construction documents such as plans and comfort system sizing calculations. This information is used to conduct a computer simulation analysis that provides the HERS Index score. Raters may also fill out checklists to independently verify that homes meet the requirements for labeling programs, such as ENERGY STAR and DOE Zero Energy Ready Home.