IECC – Energy Conservation Code Book (2021 Edition)

2021 IECC Energy Conservation Code Book

The 2021 International Energy Conservation Code (IECC), developed by the International Code Council (ICC), serves as a model code establishing minimum energy efficiency requirements for new residential and commercial buildings.

It addresses key elements such as insulation, windows, lighting, water heating, and appliance efficiency. That year’s update introduced several significant improvements, emphasizing reduced energy costs, clearer guidelines for verifying construction quality—particularly regarding air sealing and insulation—and greater alignment between standards for homes and commercial structures. These revisions are intended to reduce overall energy consumption and support environmental sustainability.