ANSI/RESNET/ICC 301-2025 Standard for the Calculation and Labeling of the Energy Performance of Dwelling and Sleeping Units Using an Energy Rating Index

The RESNET/ICC 301 American National Standard establishes the nationally recognized methodology for calculating, rating and labeling the energy performance of dwelling and sleeping units using the Energy Rating Index (ERI). Developed through ANSI-approved consensus procedures and sponsored by RESNET and the International Code Council, this fourth edition provides the authoritative framework for consistent, credible and uniform residential energy ratings across housing types.

This standard defines how a home’s energy performance is measured relative to a reference home aligned with the 2006 International Energy Conservation Code (IECC), by producing a clear numerical index: 100 represents the reference home, and 0 represents a home that achieves zero net purchased energy. The 2025 edition continues the evolution of the standard by incorporating updated technical requirements, expanded scope and enhanced carbon emissions metrics.

Used by rating providers, certified raters, builders, program administrators and code officials, ANSI/RESNET/ICC 301–2025 ensures transparency, comparability and technical rigor in residential energy analysis. It establishes the calculations, verification protocols and documentation requirements necessary to produce projected and confirmed ratings that support compliance pathways, performance programs and market transformation.

This Book Includes:

• Energy Rating Index (ERI) calculation methodology
• CO₂e Rating Index and operational carbon emissions metrics
• Energy rating reference home specifications and minimum rated features and inspection requirements
• Calculation procedures for software rating tools
• Infiltration, ventilation and distribution system efficiency modeling and HVAC system performance metrics and testing requirements
• On-site power production and battery storage treatment
• Retrofit savings calculations for existing homes and cost-effectiveness analysis of energy improvements
• Labeling and documentation requirements for certified ratings
• Procedures for averaging ratings in multifamily buildings