Glossary · Programs & credentials
IECC (International Energy Conservation Code)
Also called: 2021 IECC · 2024 IECC
The model US energy code for new homes and additions, updated about every three years; states and cities adopt an edition, often with changes.
What it means
The International Code Council develops the IECC through a consensus process and typically publishes a new edition every three years, such as 2021 and 2024. It sets minimum insulation, window, airtightness, duct and equipment requirements, and its climate zone map is used across US building guidance. DOE estimated that the 2024 edition saves about 7.8% of site energy compared with the edition before it.
Why it matters in an audit
The edition your state or city has adopted sets the minimum insulation, airtightness and window levels for additions and major renovations.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| 2024 IECC (DOE determination, Dec 20, 2024) | About 7.8% site energy, 6.8% source energy and 6.6% energy cost savings vs. the previous edition | energycodes.gov ↗ |
| State review deadline for the 2024 IECC | States must certify their residential code review by Dec 30, 2026 | energycodes.gov ↗ |