California ECC Program 2026: Energy Code Compliance Guide

The California ECC (Energy Code Compliance) program replacing HERS field verification in 2026: what it is, who it applies to, the FV&DT tests, and how the January 1, 2026 transition works.

What the ECC Program Is: ECC stands for Energy Code Compliance: the California Energy Commission's renamed and restructured framework for the field verification and diagnostic testing that used to live under the HERS (Home Energy Rating System) program. The name HERS caused persistent confusion because i

Who It Applies To, and When: ECC applies to projects permitted under the 2025 Energy Code, that is, projects with a building permit application dated on or after January 1, 2026. It covers the same residential and applicable nonresidential work that previously required HERS field verification: new constructi