Virginia’s new building envelope requirements became effective on September 4, 2018. The biggest change was adding the new Energy Rating Index (ERI) compliance path with an ERI target of 62, with and without renewable energy. Prescriptive R-values and U-factors remain unchanged.

Currently, the majority of homes built in Virginia comply using the performance path. While the ERI path is viewed as more stringent, over time, more builders may switch to the ERI path because it provides compliance credit for onsite renewable generation, Energy Star, and other measures that the performance path does not.

Overview of Building Envelope Requirements in Virginia’s USBC

  • The September 2018 changes created a new compliance path, the ERI, with a compliance target of 62 (rather than 54 in the 2015 IECC model code).
  • When the ERI compliance path is used, insulation levels must meet or exceed 2009 International Energy Conservation Code (IECC) model code prescriptive requirements.
  • If onsite renewable power is used, insulation levels must meet the 2015 IECC envelope requirements.

What is the Energy Rating Index?

The ERI provides a new path for energy code compliance. Builders using this path need to achieve a certain score, on a scale from 0 to 100, to achieve energy efficiency code compliance for building construction. A lower score means a more energy efficient home. The score of 100 aligns with the 2006 IECC model code.

In Virginia, the target score is 62, and RESNET-accredited software is used to calculate the ERI score. The ERI path carries certain mandatory elements, and there are two distinctions for builders using the ERI path:

  • The ERI path is distinct from the Home Energy Rating System (HERS index scale) since other approved home rating programs could in theory be used for ERI compliance.
  • Both HERS and ERI allow for the use of renewable energy to reduce scores, however, ERI includes provisions to ensure that renewable energy does not replace more permanent or reliable energy efficiency measures. As a matter of practice, the ERI path calls for builders to use HERS to demonstrate building code compliance. Therefore, if the ERI path is used for energy code compliance and renewable energy is incorporated, builders must construct a building envelope that meets the prescriptive envelope requirements of 2015 IECC.

To view a listing of key changes to building envelope requirements of the 2015 Virginia USBC, download the detailed summary.

This summary is offered for informational purposes only. It does not purport to be an exhaustive analysis of code changes or provide advice that will ensure guaranteed compliance with any energy code provision. Please consult with local authorities before finalizing your installation plans.

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