Not sure which energy code requirements apply to your project? Find out!

Energy Codes in Massachusetts

With over 30+ years of experience in the industry, our team of 9 RESNET Certified HERS Raters and 4 Rating Field Inspectors has the knowledge and expertise you need to ensure that your project complies with all energy codes. Click here to learn more about our energy code compliance services.



Massachusetts has a base energy code that all new buildings in the state must follow. It is based on the most current version of the International Energy Conservation Code (IECC) which establishes a baseline for energy efficiency by setting performance standards for the building envelope. Provided the mandatory requirements are met, the rest of the code can be met by either following the prescriptive or performance path.

Performance Path Compliance:

The performance path requires energy modeling to demonstrate that the building as a whole uses equal or less energy than a home built to the prescriptive path. Even though the performance path is slightly more involved, it allows flexibility to trade off many of the high-cost assemblies required in the prescriptive path resulting in substantial savings.

To comply with the Performance Path, you will need either a simulated energy performance analysis or an Energy Rating Index (ERI) analysis. The ERI path, specifically a certified RESNET HERS Rating, is the performance path most often used to achieve energy code compliance in base energy code communities.

We highly recommend following the Performance Path utilizing a HERS Rating.  A HERS Rating is the most realistic compliance option that offers documented energy savings while giving you more flexibility and “trade offs”.

Prescriptive Path Compliance:

The prescriptive path requires that each component is built to a specified R-value or U-value found in the prescriptive table. While the prescriptive path is a traditional approach and can be achieved without the aid of any software, it does not have much flexibility and therefore does not allow trade-offs to lower assembly cost.

To comply with the Prescriptive Path, you will need:

  • A REScheck certificate
  • Performance Testing – blower door test, duct testing, and ventilation testing
  • To meet insulation specifications
  • To meet window performance specifications

**This path is not eligible for Mass Save incentives**

IECC/HERS Compliance Specialist

As a certified IECC/HERS Compliance Specialist, Home Energy Raters can now help code officials save time, energy and resources by assisting with code jurisdiction and energy code compliance.  To learn more, click here.




In 2009, Massachusetts became the first state to adopt an above-code appendix to the base building energy code known as 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 mandatory state-wide IECC base code.

Stretch Code Compliance:

In order to meet the requirements of the Stretch Code, builders must hire a certified HERS Rater, like Home Energy Raters, to perform a series of tests (HERS Rating) to determine if the home meets energy code compliance. The Stretch Energy Code (2021 IECC w/ MA Amendments) has changed as of January 1, 2023, for residential buildings 3 stories or less. For 4+ story residential buildings, the 2023 Multifamily & Commercial Code went into effect on 7/1/23.

On 7/1/24, substantial changes to the Massachusetts building code went into effect for municipalities that have adopted the Stretch Energy Code. There is an overall push to remove fossil fuels from new buildings and higher HERS Ratings will be allowed for all-electric buildings.




Residential New Construction Projects:

  • HERS 42 for buildings with any mixed-fuel buildings
  • HERS 42 for buildings with any mixed-fuel buildings with solar electric generation
  • HERS 45 for all-electric buildings
  • HERS 45 for all-electric buildings with solar electric generation

Renovation/Addition Projects:

  • HERS 52 for buildings with any mixed-fuel buildings
  • HERS 55 for buildings with any mixed-fuel buildings with solar electric generation
  • HERS 55 for all-electric buildings
  • HERS 58 for all-electric buildings with solar electric generation

– 1 EV-Ready space and wiring per house required (EV-Ready also required for multi-family projects but requirements vary)
– ERV or HRV will now be required. Bath fans no longer meet the requirement for whole- house mechanical ventilation. There are some models we recommend using (with lower wattage) that help the HERS Rating, but you can use any brand you would like. You will still need to meet the required CFM of ventilation.
– HVAC duct leakage testing is now required for all systems, even if all ducts are within the conditioned envelope
– HERS Ratings will be required for additions over 1,000 sq ft and/or over 50% of the original structure (Level 3 Alteration per IEBC)




Most municipalities in Massachusetts have adopted the Stretch Code – take a look at the map below to see if the town/city you are building in has adopted this new energy code. For more information about about the Stretch Code, check out out our “Stretch Energy Code & Municipal OPt-In Specialized Building Code FAQs” article.


Map of current energy code adoption in each municipality in MA




Starting July 1, 2023, municipalities can vote to approve the “Specialized Stretch Code” which will require Net Zero/Zero Energy, solar, and lower HERS Ratings. Municipalities that opt-in to this are likely to provide a 6-9 month grace period.

The following municipalities have adopted this new specialized Stretch Code:

Effective 7/1/23: Brookline, Cambridge, Somerville, Watertown
Effective 1/1/24: Action, Aquinnah, Arlington, Boston, Concord, Lexington, Lincoln, Maynard, Newton, Northampton, Sherborn, Stow, Truro, Wellesley, Wellfleet, Worcester
Effective 7/1/24: Amherst, Bedford, Carlisle, Chelmsford, Medford, Melrose, Needham, Norwood, Salem, Swampscott, Wakefield, Weston, Worcester
Effective 1/1/25: Ashfield, Ashland, Belmont, Dedham, Eastham, Easthampton, Hopkinton, Milton, Sharon, Wayland, West Tisbury
Effective 1/1/25:
Natick, Newburyport

Specialized Energy Code Compliance:


Our team is here to help you meet these new code requirements. Please call our office at 508-833-3100 or send us an email to to schedule a time to review your upcoming  projects. We will work with you to help value-engineer your projects and maximize any available incentives.