MA Stretch Code Compliance in Boston, MA
Complete MA Stretch Code 2021 (IECC 2021) compliance services for new residential construction in Boston, MA — from plan review through HERS certification.
2026 Massachusetts Energy Code Facts — Boston
Boston enforces the Municipal Opt-in Specialized Energy Code (225 CMR 23), effective 1/1/2024 — one of only 60 Massachusetts municipalities to adopt it (a Stretch Code community since 7/1/2011). For 2026 permits, new homes must reach a maximum HERS Index of 42 (mixed-fuel) or 45 (all-electric) — up to 48 with qualifying credits — verified by a RESNET-certified HERS rater. ADUs must meet HERS 52–58, and major alterations, additions or change-of-use projects HERS 65–75, depending on fuel type and on-site solar.
- Energy code status: Specialized Opt-in Code (adopted 1/1/2024) — 1 of 60 MA municipalities (as of the June 2026 Mass.gov adoption list).
- Specialized Code requirements in Boston: new multifamily buildings over 12,000 sq ft must be Passive House certified; all-electric homes must use heat pumps for heating and hot water; homes that keep fossil fuels need electrification pre-wiring and rooftop solar, and fossil-fuel homes over 4,000 sq ft must certify net-zero (HERS 0).
- Required testing & verification: blower door (air infiltration) testing, duct leakage testing, balanced mechanical ventilation (ERV/HRV), plus EV-ready and solar-ready provisions on the HERS compliance path.
- Mass Save® 2026 new-construction incentives: up to $25,000 per all-electric single-family home (Passive House tier; $7,500 base tier, $15,000 ENERGY STAR® NextGen tier — HERS ≤45), up to $40,000 for a 4-unit building, up to $3,750/unit for 5+ unit multifamily, and up to $30,000 for major all-electric renovations. Every tier requires enrollment and verification by an approved HERS rating company.
Related Boston services: HERS Rating Boston · Blower Door Testing Boston · Duct Leakage Testing Boston · MA Energy Codes Guide — or get a free quote from our RESNET-certified team (617-584-1809).
Sources: 2025 DOER Massachusetts Stretch & Specialized Codes Technical Guidance (Sept 2025); Mass.gov Building Energy Code Adoption by Municipality (June 2026); Mass Save 2026 Residential New Construction program.
Common Questions About the Boston Energy Code
Does Boston require a HERS rating in 2026?
Yes. Boston follows the Municipal Opt-in Specialized Energy Code (effective 1/1/2024) on top of the Stretch Code it adopted in 7/1/2011. New dwellings need a certified HERS rating from a RESNET-accredited rater before the certificate of occupancy.
What HERS score is required in Boston?
New homes in Boston must score HERS 42 or lower (mixed-fuel) or HERS 45 or lower (all-electric) — up to 48 with qualifying credits. Fossil-fuel homes over 4,000 sq ft must certify net-zero (HERS 0), and multifamily over 12,000 sq ft needs Passive House certification.
Which energy code does Boston follow in 2026?
Boston is one of only 60 of Massachusetts’ 351 municipalities on the Specialized Opt-in Code (225 CMR 23) per the June 2026 Mass.gov adoption list — the state’s most stringent energy code tier.
Official Maximum HERS Index Scores (Table R406.5)
These are the official maximum HERS Index scores that apply to projects in Boston under Table R406.5 of the current code (2025 DOER Technical Guidance):
| Building type | New construction (permits after 7/1/2024) | New construction w/ embodied-carbon credit (R406.5.2) | Accessory Dwelling Units | Major alterations, additions, change of use |
|---|---|---|---|---|
| Mixed-fuel building | 42 | 45 | 52 | 65 |
| Mixed-fuel + solar electric | 42 | 45 | 55 | 70 |
| All-electric building | 45 | 48 | 55 | 70 |
| All-electric + solar electric | 45 | 48 | 58 | 75 |
Scores are measured before counting on-site renewable generation (per R406.5). Historic buildings may opt out for alterations under R503.1.1. Embodied-carbon credits (+3 points) come from low-GWP concrete and insulation EPDs per Table R406.5.3/R406.5.4.
Complete Stretch Code Compliance Requirements in Boston
Beyond the HERS maximums above, every new dwelling in Boston on the HERS pathway must satisfy four code sections — R403.6 (Ventilation), R404.4 (EV Ready), R406 (HERS) and Appendix RB (Solar Ready) — per the 2025 DOER Technical Guidance:
- Balanced mechanical ventilation (R403.6): an ERV or HRV system meeting minimum system airflow, heat/energy-recovery efficiency, fan sound ratings and regulated air-inlet and exhaust locations — verified by field testing.
- EV-Ready parking (R404.4): pre-wiring with a connection point and dedicated electrical panel capacity for future vehicle charging.
- Solar-Ready roof (Appendix RB): a dedicated solar zone with structural-load verification, an electrical interconnection pathway and reserved panel space — unless the project installs solar directly.
- Air-tightness & duct sealing: blower door result of 3.0 ACH50 or lower (Climate Zone 5) and duct leakage within 4 CFM25 per 100 sq ft.
Passive House alternative (R405): Phius or PHI certification satisfies the code in Boston in place of a HERS score — with a Certified Passive House Consultant for design and a Phius Certified Verifier/Rater during construction — and still requires EV-Ready and Solar-Ready compliance. Prescriptive path: allowed only for buildings without individually separate dwelling units, additions, and alterations — and a whole-building prescriptive project must implement 2 of the 3 additional-efficiency packages in R408 (enhanced envelope, higher-efficiency HVAC, or reduced water-heating energy). Additions of 1,000 sq ft or more (or exceeding 100% of the existing floor area) must meet both R502.3 prescriptive and the R406.5 HERS limits. Level III alterations (work area over 50% of the home and over 1,000 sq ft) also trigger HERS compliance; historic buildings are exempt under R501.6. Note that ENERGY STAR® is no longer a compliance path — HERS and Passive House are the two certification routes in Boston.
Boston’s Specialized Code: Three Ways to Comply (Appendix RC)
- Zero Energy Pathway (RC102): certify HERS 0 or lower — the home produces as much energy as it uses. Before counting on-site solar, the design must still score ≤45 (all-electric) or ≤42 (mixed-fuel) and meet IECC 2021 envelope U-factors. Alternative: Passive House plus a Phius ZERO design certification — the only Specialized option that can credit off-site renewable energy.
- All-Electric Pathway (RC103) — the most common route in Boston: comply with the R408.2 HVAC and water-heating efficiency packages (electric-resistance primary heating is excluded — heat pumps required), meet EV-Ready and Solar-Ready, then either achieve a final certified HERS of 45 or less without on-site power (with ERV/HRV, R406.2 lighting, and base-code U-factors) or pre-certify to Phius CORE / PHI. With load-management design, most all-electric homes run on a standard 200-amp panel.
- Mixed-Fuel Pathway (RC104) — only for dwellings under 4,000 sq ft: score HERS 42 or less without on-site power, plus electric-readiness (RC104.3), on-site renewables (RC104.4/RC105) and EV-Ready — or pre-certify Passive House with electric readiness. Electric readiness in Boston means a 250-volt/40-amp outlet within 3 feet of any gas or propane range, a 250-volt/30-amp outlet within 3 feet of the clothes dryer, a reserved branch circuit for a future heat-pump heating system, and a heat-pump water-heater location with 7-foot clearance.
Detail sourced from the 2025 Massachusetts Stretch & Specialized Codes Technical Guidance (DOER, Sept 2025), Table R406.5 and Appendix RC.
MA Stretch Code 2021 Compliance Services in Boston, Massachusetts
Complete MA Stretch Code 2021 compliance services for new construction in Boston, MA. We manage the entire process — plan review, energy modeling, blower door testing, duct leakage testing, and final HERS certification — so your project meets all requirements.
Boston has adopted the MA Stretch Code, requiring new residential buildings to achieve: HERS score 55 or below · blower door 3.0 ACH50 or less · total duct leakage 4% or less. All requirements must be verified by a RESNET-certified rater.
Our MA Stretch Code Compliance Process in Boston
- Plan Review & Quote: Submit your building plans. We review them, model them to a HERS score, and provide a compliance roadmap and quote.
- Pre-Construction Modeling: We model your plans to a HERS score before construction begins — identifying compliance risks cost-effectively.
- Construction Phase Testing: Intermediate blower door and duct tests verify compliance during construction.
- Final Certification: Final HERS Rating, RESNET-certified compliance report, and documentation for your building department.
Related Services in Boston
HERS Rating in Boston
HERS score 55 or below required for MA Stretch Code.
Learn More →Blower Door Testing in Boston
3.0 ACH50 or less required under MA Stretch Code.
Learn More →Duct Leakage Testing in Boston
4% or less total duct leakage required for forced-air systems.
Learn More →Frequently Asked Questions — MA Stretch Code Compliance in Boston
How much does MA Stretch Code compliance cost in Boston?
MA Stretch Code compliance package pricing in Boston: Single-family homes $1,850–$2,500 · Multifamily (per unit) $650–$1,200 · ADUs $1,600–$1,850. Full package includes HERS Rating, blower door testing, and duct leakage testing. Contact us for a free, project-specific quote.
Does Boston require the MA Stretch Code?
Yes. Boston has adopted the MA Stretch Code, requiring new residential construction to achieve: HERS score 55 or below · blower door 3.0 ACH50 or less · total duct leakage 4% or less — all verified by a RESNET-certified rater.
How do I prove MA Stretch Code compliance in Boston?
Compliance is documented through a RESNET-certified HERS Rating report. Our reports are accepted by the Boston building department and all Massachusetts municipalities as proof of MA Stretch Code compliance.
What is included in the full MA Stretch Code compliance package?
Our full compliance package for Boston includes: energy modeling from building plans · blower door air leakage test · duct leakage test · final HERS Rating · RESNET-certified compliance report for the building department.
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Get MA Stretch Code Compliance in Boston
Contact HERS Rating Company for a free quote on MA Stretch Code 2021 compliance in Boston, MA. Full package: HERS Rating, blower door, and duct leakage testing.
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