What does the HERS Index score represent?

The HERS Index score specifically measures a home's energy efficiency compared to a reference home built to the 2006 International Energy Conservation Code (IECC). A score of 100 on the HERS Index signifies that the home meets the energy standards of the reference home, while lower scores indicate greater energy efficiency. For example, a score of 60 indicates that the home is 40% more energy efficient than the reference home, while a score above 100 indicates less efficiency. The index takes into account various factors, including insulation levels, HVAC efficiency, and the overall design which impact how much energy is needed to maintain comfort.

This scoring system is valuable for homeowners, builders, and appraisers as it quantifies the energy performance of a home. It does not directly measure energy consumption alone, total costs of energy bills, or average temperatures within the home. Instead, it encapsulates a broader picture of how efficiently a home's energy is used.