2025 Massachusetts Building Energy Codes

Massachusetts has three levels of building energy codes, each designed to improve energy efficiency across residential and commercial buildings. Below, we break down the different codes and provide links to the latest documents for reference.

Massachusetts Building Energy Codes

The Massachusetts building energy codes are based on the International Energy Conservation Code (IECC) 2021 with state-specific amendments. There are three levels:

1. Base Code (Standard Statewide Code)

The Base Code is the default energy code applied across Massachusetts. It follows:

• Residential: IECC 2021 with Massachusetts amendments (780 CMR Chapter 11R)
• Commercial: IECC 2021 with Massachusetts amendments (780 CMR Chapter 13)

The 780 CMR 10th Edition is the official building code currently enforced in Massachusetts.

2. Opt-in Stretch Code

Municipalities can adopt the Stretch Code, which goes beyond the Base Code for better energy efficiency. It includes:

• Residential: IECC 2021 with Massachusetts amendments (225 CMR Chapter 22)
• Commercial: IECC 2021 with Massachusetts amendments (225 CMR Chapter 23)

3. Opt-in Specialized Code

For even stricter energy standards, some municipalities may adopt the Specialized Code, which includes additional energy performance requirements:

• Residential: IECC 2021 with Massachusetts amendments (225 CMR Chapter 22 + Appendix RC)
• Commercial: IECC 2021 with Massachusetts amendments (225 CMR Chapter 23 + Appendix CC)

Municipality Code Adoption

Different municipalities across Massachusetts may follow different energy codes based on their energy efficiency goals. The map below provides an overview of which level of code is adopted by each municipality.

Latest Massachusetts Energy Code Documents (2025 Update)

As of February 14, 2025, the most up-to-date energy code documents are:

• IECC 2021
• Stretch & Specialized Code – Residential
• Stretch & Specialized Code – Commercial
• 780 CMR 10th Edition (Massachusetts Building Code)

Conclusion

Understanding the Massachusetts building energy codes is crucial for architects, builders, and homeowners looking to ensure compliance and improve energy efficiency. With the Base, Stretch, and Specialized Codes in place, municipalities can choose the level of efficiency that best aligns with their sustainability goals.