Building Energy Code

Summary of State Building Energy Codes including the Stretch Code

Table of Contents

Energy Efficiency Provisions of the State Building Code

As part of the Green Communities Act of 2008, Massachusetts is required to update its building code every three years to be consistent with the most recent version of the International Energy Conservation Code (IECC). This ensures that new buildings are designed and constructed with energy efficiency in mind. In 2009, Massachusetts became the first state to adopt an above-code appendix to the "base" building energy code-the "Stretch Code". The Stretch Code, which emphasizes energy performance, as opposed to prescriptive requirements, is designed to result in cost-effective construction that is more energy efficient than that built to the "base" energy code. The Stretch Code is typically updated every few years, with the most recent update to take effect in 2023.

The Stretch Energy Code (Stretch Code) regulations have since 2009 been published in MA 780CMR chapters 115.aa and previously 780 CMR 110.aa under the jurisdiction of the Board of Building Regulations and Standards. The Climate Act of 2021 moved the authority for the Stretch Code promulgation to the Department of Energy Resources (DOER) and at the same time required the development of a new Municipal Opt-in Specialized energy code (Specialized Code). The statute requires that the Specialized Code is formulated to ensure new construction that is consistent with Massachusetts greenhouse gas limits and sub-limits set every five years from 2025 to 2050. The updated Stretch Code is divided into two chapters, following the format of the IECC and appear as new regulations in 225 CMR 22.00 and 225 CMR 23.00. 

The Specialized Code includes additional requirements that form an Appendix to each of the chapters of the Stretch Code.

• CMR 22.00 covers Residential low-rise construction, Appendix RC includes provisions for the Specialized Code in residential construction,  and

• CMR 23.00 covers Commercial and all other construction (including most multi-family), Appendix CC includes provisions for the Specialized Code for commercial construction.

Therefore, current energy code options are as follows:

•    Current Base Energy Code = IECC 2018 with MA amendments (to be updated in 2023)

•    Updated Stretch Code = IECC 2021 with MA amendments + Stretch Code amendments

Graphic showing details of Base Code (IECC 2021) - Stretch Code (2023 Update) - Specialized Code ("Net-Zero")
Current Energy Code Options

•    Specialized Code = IECC 2021 with MA amendments + Stretch Code amendments + Specialized Code appendices

Additional Resources

Building Energy Code Adoption by Municipality

Building Energy Code Adoption by Municipality

Current building energy code options are as follows:  
Current Base Energy Code = IECC 2018 with MA amendments (to be updated in 2023)
•    Updated Stretch Code = IECC 2021 with MA amendments + Stretch Code amendments (225 CMR 22.00 and 225 CMR 23.00)
•    Specialized Code = IECC 2021 with MA amendments + Stretch Code amendments + Specialized Code appendices amendments (225 CMR 22.00 (appx. RC) and 225 CMR 23.00 (appx. CC))

Municipalities may choose to adopt the Stretch Code in lieu of the Base Energy Code. Stretch code adoption is mandatory for designation as a Green Community under the Green Communities Act passed by the Legislature and signed into law in 2008. 

Stretch Code “Residential Cash Flow Analysis”

DOER hired an independent building energy consulting firm to look at the cost-benefit equation of building a representative set on new single-family and multi-family homes to the updated 2023 Stretch Code and the Specialized Code.

Additional Resources

Massachusetts Energy Code Training

The Mass Save statewide energy efficiency program in coordination with the Board of Building Regulation and Standards (BBRS) and DOER is continuing to sponsor training on the building energy code, including the Stretch Code and Specialized Code, at various locations around the state. The training is open to all,and developed to serve both building officials and other building professionals (e.g., builders & architects). Training is free for building officials and counts toward the new BBRS requirement that building officials be trained in energy efficiency. Other building professionals pay a nominal fee for the training and may receive continuing education units (CEU's) for attending. 

To get information on energy code training and events, click here.

Additional Resources

Contact   for Building Energy Code


100 Cambridge Street, 9th Floor, Boston, MA 02116

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