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A significant cohort of approximately 2,900 registered home energy ratings using the REM/Rate HERS software tool, as reported to RESNET, are subjected to statistical analysis by the Dillon Group, Inc. The statistical analysis determines the distribution of HES results as a function of home energy efficiency as measured by the minimum standards of the 2009 IECC and by EPA’s ENERGY STAR program.

In addition, a parametric simulation analysis is conducted by the Florida Solar Energy Center using EnergyGauge® USA version 5.0, a RESNET-accredited HERS software tool, to determine the relationship between HES scores and the HERS Index. The parametric analysis uses a series of three archetypical homes, each configured to represent the 2006 IECC standard reference design (the HERS Reference), the 2012/2015 IECC prescriptive standard and the 2015 IECC Section R406 Energy Rating Index (ERI) standard. Each of the archetypical homes is configured using two fuel options: 1) all electric space and water heating equipment and 2) natural gas space and water heating equipment. The parametric analysis is conducted in three diverse climates (Chicago, Atlanta and San Diego) to examine the relationship between the HES score and the HERS Index.

Findings from the study and analysis show that a correlation between HERS Index scores and HES scores is not achievable. Further, results show that there is no relationship between HES scores and home energy efficiency as measured by either IECC building code standards or EPA’s ENERGY STAR new homes program. The findings are fully consistent with the fact that HES is a measure of absolute home energy use while the HERS Index and building energy codes are measures of home energy efficiency or relative home energy performance.

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