The HERS (Home Energy Rating System) Index allows buyers to compare the relative energy efficiency of different homes. The HERS Index home energy rating is determined by an independent RESNET-certified home energy rater ("Rater"). The lower a home's score, the more energy efficient it is in comparison to the HERS referenced home. For every one-point decrease in the HERS Index score, there is a corresponding one percent (1%) reduction in energy consumption as compared to a home with a HERS Index of 100. See the bottom of this page for more information on HERS scores.