HERS Rating in Westport, MA — Stretch Code HERS 42/45
RESNET-certified HERS Ratings for new construction, renovations, Mass Save programs, and MA Stretch Code compliance in Westport, MA.
2026 Massachusetts Energy Code Facts — Westport
Westport enforces the Massachusetts Stretch Energy Code (225 CMR 22), adopted effective 7/1/2018. Under the 2025 code update (current for 2026 permits), new homes in Westport 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: Stretch Code (effective 7/1/2018) — 1 of 242 MA municipalities (as of the June 2026 Mass.gov adoption list).
- 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 Westport services: Blower Door Testing Westport · Duct Leakage Testing Westport · Stretch Code Compliance Westport · 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 Westport Energy Code
Is a HERS rating required in Westport, MA?
Yes. Westport has enforced the Massachusetts Stretch Energy Code since 7/1/2018, so new dwellings need a certified HERS rating from a RESNET-accredited rater — with blower door and duct leakage testing — before the certificate of occupancy.
What HERS index do new homes in Westport need to hit?
Homes permitted in Westport today must score HERS 42 or lower (mixed-fuel) or HERS 45 or lower (all-electric), up to 48 with qualifying credits. ADUs fall in the HERS 52–58 range and major alterations/additions in the 65–75 range, depending on fuel type and on-site solar.
What building energy code is Westport on right now?
Westport is one of 242 of Massachusetts’ 351 municipalities enforcing the Stretch Energy Code (225 CMR 22) per the June 2026 Mass.gov adoption list; 60 towns have gone further to the Specialized Code and 49 remain on the Base Code.
Official Maximum HERS Index Scores (Table R406.5)
These are the official maximum HERS Index scores that apply to projects in Westport 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 Westport
Beyond the HERS maximums above, every new dwelling in Westport 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 Westport 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 Westport.
Detail sourced from the 2025 Massachusetts Stretch & Specialized Codes Technical Guidance (DOER, Sept 2025), Table R406.5 and Appendix RC.
Professional HERS Rating Services in Westport, Massachusetts
RESNET-certified HERS Ratings for new construction, renovations, Mass Save programs, and MA Stretch Code compliance in Westport, MA. Our RESNET-certified raters serve Westport and all 351 Massachusetts cities and towns.
New homes in Westport must achieve a HERS score of 55 or below under the MA Stretch Code. HERS Rating Company manages the complete compliance process — from initial energy modeling through on-site testing and certified report delivery.
Our HERS Rating Process in Westport
- Free Quote: Contact us for a transparent, no-surprise quote for your project in Westport.
- Plans Review: We review building plans and create an energy model before construction begins.
- Site Inspection: Our RESNET-certified rater visits your Westport property and performs all required tests.
- 24-Hour Report: Receive your certified HERS Rating report within 24 hours — ready for permit submission and Mass Save applications.
Related Services in Westport
Blower Door Testing in Westport
Required air tightness test — included with every HERS Rating.
Learn More →Duct Leakage Testing in Westport
Required duct blaster test for forced-air HVAC systems.
Learn More →MA Stretch Code in Westport
Full IECC 2021 Stretch Code compliance from plan review to certification.
Learn More →Frequently Asked Questions — HERS Rating in Westport
How much does a HERS Rating cost in Westport, MA?
HERS Rating pricing in Westport depends on project type: Single-family homes $1,850–$2,500 · Multifamily (per unit) $650–$1,200 · ADUs $1,600–$1,850. Contact us for a free, no-obligation quote for your specific project.
Is a HERS Rating required for new construction in Westport?
Yes. Westport has adopted the MA Stretch Code, which requires all new residential construction to achieve a HERS score of 55 or below. A RESNET-certified HERS Rating is required to document compliance.
How long does a HERS Rating take in Westport?
The on-site inspection in Westport typically takes 2–4 hours. We deliver your certified HERS report within 24 hours of the site visit.
What is the HERS score requirement for MA Stretch Code?
New construction in MA Stretch Code municipalities like Westport must achieve a HERS score of 55 or below. The Specialized Stretch Code (adopted in some towns) requires HERS 45 or below for homes over 3,000 sq ft.
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