After more than 18 months of working with the Updated Stretch Energy Code and the newly created Municipal Opt-in Specialized Code, the Massachusetts Department of Energy Resources (DOER) proposed a series of updates to these codes based on feedback from the Home Builders and Remodelers Association of Massachusetts and other stakeholders. After a public hearing and adjustments based on additional feedback, the updates went into effect on February 14, 2025, See 225 CMR 22.00.
Below is a summary of the more significant changes for residential construction.
New Construction
Embodied Carbon Credit – A new home can earn a 3-point HERS credit for embodied carbon savings earned through the use of either low embodied carbon concrete or insulation products. This 3-point credit means that the maximum HERS score for a mixed-fuel building would be 45 rather than 42, and 48 rather than 45 for an all-electric building.
ADUs get a relaxed HERS target – Accessory Dwelling Units (ADUs) will retain a HERS 52-58 range (rather than the 42-48 range for all other residential applications) in order to not hamper the development of smaller ADUs.
Ceiling Insulation minimum R-Value reduced – The minimum requirement of R-60 for ceiling insulation has been reduced to R-49.
Alterations and Additions
Finished basements and attics – Additions that add existing basement or attic spaces to the conditioned floor area of an existing dwelling unit due to changing the thermal boundary, but not changing the building footprint or roofline, do not require a HERS rating.
Historic Buildings – For large changes to historic buildings, the HERS rating requirement is removed, allowing the project to follow a modified prescriptive compliance path.
Another clarification makes clear that projects meeting the definition of Extensive Alterations or Level 3 Alterations must also exceed 1,000 sq. ft. in order to trigger a HERS rating requirement for the entire dwelling unit.
Major Alterations and Large Additions also get a relaxed HERS target – For Major Alteration and Large Additions (greater than 1,000 sq. ft.) and change of use projects that require a HERS rating, there is an increase (loosen) to the HERS rating requirement, now with the range of HERS scores moving from 52-58 to 65-75.
The adoption of these more realistic and achievable HERS targets was an important achievement for the association, especially as they relate to remodeling projects and the construction of ADUs.
