Understanding HERS Ratings
Methodology of Calculating the HERS Index
The HERS Index rating is based on the relevant home plan specifications including interior and exterior options, appliances and features, and on the location, orientation and manner in which the home is built. These specifications along with performance test results are entered into RESNET-approved software, which includes RESNET-determined inputs and certain assumed conditions. The home’s modeled site-level energy consumption is compared against the modeled consumption of the same home (the reference home) if built to the 2006 International Energy Conservation Code (IECC).
The typical new home HERS Index rating for the reference home is 100. However, more stringent changes to the Florida Building Code, has code built homes averaging around a score of 82 on the HERS index scale. If a new home scores a 65, it is calculated to perform 21 percent more efficiently than a Florida code built new home. The typical existing home built before the 2006 IECC code averages a HERS Index rating of 130. A HERS Index rating of 130 is a U.S. Department of Energy rating per its EnergySmart Home Scale.
Certificate and Label HERS Index
The as-built HERS Index rating for the home is calculated based on site inspection findings, performance testing, and an analysis of the final construction plans by SkyeTec, a RESNET-certified independent energy rating firm. Each home also undergoes a rigorous third party review by a RESNET provider before the final HERS Index certificate is produced. The as-built HERS Index may vary from the as-designed rating shown on the base plan depending on changes made to the relevant home plan, including changes in interior and exterior options, appliances or features, or on the location, orientation and manner in which the home is built.
Methodology for Calculating the Estimated Monthly Utility Bill Amount
The estimated monthly electric and gas energy bill cost is simultaneously generated from RESNET-approved software using assumptions about annual energy use solely from the heating and cooling systems, appliances and lighting that are included as standard with the relevant home plan, and average local energy utility rates available at the time the estimate is calculated. Gas utilities may not be available in some communities and energy utility costs in those communities will reflect only electrical utilities. Even as the home is modeled in the software as designed and built per the relevant home plan, actual energy utility costs will depend on a number of factors, including but not limited to personal utility usage preferences, the rates, fees and charges of local energy utility provides, daily activities, home maintenance practices, household size, use and/or condition of appliances, lighting and internal climate control systems, and the surrounding climate and weather conditions. As the estimated monthly utility bill amount may not reflect lifestyle factors, the number provides a comparison tool for homebuyers.
Limitations and Exclusions
The HERS Index rating is a measurement of a home's energy efficiency per RESNET standards, but it is not a warranty or guarantee of energy utility costs or savings. Neither SkyeTec nor the builder guarantees that any specific level of electric and gas energy utility cost or savings will be achieved or maintained.