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Adoption of HERS Index and ERI

The HERS Index was created by the Residential Energy Services Network (RESNET), and its adoption as the national standard highlights the leading role played by RESNET in moving America towards greater energy efficiency. The most commonly used ERI in the U.S. is the HERS Index, which is the industry standard for measuring a home’s energy efficiency and the nationally recognized system for inspecting, testing and calculating a home’s energy performance.

The Energy Rating Index (ERI) is an optional compliance path, incorporated in the International Energy Conservation Code (IECC) since 2015. In the 2018 IECC, ANSI/RESNET/ICC Standard 301 serves as the basis for the ERI calculation methodology. The 2015 and 2018 IECC specify an ERI Target Score for each climate zone, as follows:

Climate Zone 2015 IECC 2018 IECC
1 52 57
2 52 57
3 51 57
4 54 62
5 55 61
6 54 61
7 53 58
8 53 58

Nearly all states and local jurisdictions use the IECC as the basis for their residential energy code. The ERI has been adopted in at least 15 States and over 300 local jurisdictions, as an energy code compliance option. RESNET’s HERS Index is the most common program for demonstrating compliance with the ERI.

To determine the cost effectiveness of the Energy Rating Index option of the 2015 IECC RESNET commissioned the Florida Solar Energy Center to conduct cost-effectiveness analysis of new homes configured to comply with the Energy Rating Index performance path provisions of the 2015 IECC[1] compared to homes configured to comply with the 2012 IECC. The analysis was conducted across all IECC Climate Zones with national averages weighted using new home construction starts. The study found that in all cases, compliance with the ERI performance path of the 2015 IECC is cost-effective.

  • Annual savings of the 2015 IECC ERI performance path, averaged across climate zones, is $468.
  • Life-cycle cost savings, averaged across climate zones, is $12,784 for the 2015 IECC ERI performance path.
  • The Savings-to-investment ratio (SIR), averaged across climate zones, is 1.69
  • The Net Present Value (NPV) averaged across climate zones, is $5,219

Why should builders use RESNET’s HERS Index to comply with ERI?

Flexibility. The ERI compliance path simply sets a target index score that builders can achieve through the most cost effective means to meet their designs.

Cost Savings. Free from the stringency of prescriptive requirements in the energy code, builders often see cost savings from using the HERS Index to comply with the ERI path, even after considering the cost of the rating.

1,900+ Certified HERS Raters ready to assist you with obtaining a HERS Rating and verifying energy code compliance using the ERI.

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