- 6175841809
- hersratingcompany@gmail.com
- 12 Pond St Ashland, MA 01721 United States
- 573 Washington St Quincy, MA 02169 United States
Certified HERS Rater serving Lexington, Massachusetts — helping builders, developers & homeowners meet the Massachusetts Stretch Energy Code and qualify for Mass Save incentives.
Get a Free QuoteCall 617-584-1809Lexington 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 1/1/2011). 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. Lexington is also an all-electric town: it is one of only 10 Massachusetts municipalities in the state’s Fossil Fuel-Free Building Demonstration Program, so new construction and major renovations here generally cannot install gas, oil, or propane systems — heat pumps and electric equipment are the standard.
Related Lexington services: Blower Door Testing Lexington · Duct Leakage Testing Lexington · Stretch Code Compliance Lexington · 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.
Yes. Lexington follows the Municipal Opt-in Specialized Energy Code (effective 1/1/2024) on top of the Stretch Code it adopted in 1/1/2011. New dwellings need a certified HERS rating from a RESNET-accredited rater before the certificate of occupancy.
New homes in Lexington 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.
Lexington 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.
These are the official maximum HERS Index scores that apply to projects in Lexington 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.
Beyond the HERS maximums above, every new dwelling in Lexington 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:
Passive House alternative (R405): Phius or PHI certification satisfies the code in Lexington 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 Lexington.
Detail sourced from the 2025 Massachusetts Stretch & Specialized Codes Technical Guidance (DOER, Sept 2025), Table R406.5 and Appendix RC.
HERS Rating Company provides certified HERS Index ratings in Lexington, Massachusetts. Our RESNET-accredited raters deliver fast, accurate energy ratings to keep your project on schedule and in full compliance with Massachusetts energy codes.
Whether building new or renovating in Lexington, MA, our certified HERS raters provide all documentation needed for building permits and final inspections.
Famous as the birthplace of the American Revolution, Lexington is an affluent suburb with one of the most active teardown-and-rebuild markets in the region, where mid-century homes are routinely replaced by large new custom houses. Our RESNET-certified raters provide the energy modeling and verification these high-value new builds require under the Stretch Code.
The MA Stretch Energy Code requires all new residential construction to be verified by a certified HERS rater. Builders in Lexington must meet IECC 2021 requirements including air tightness tested by blower door and duct leakage verified by duct leakage testing. We provide all documentation required by the Lexington building department.
Ready to schedule your HERS rating in Lexington, MA? Get a fast, free quote today.
Schedule Your HERS RatingCall 617-584-1809HERS Rating costs in Lexington typically depend on home size, design complexity, and the number of required site visits. For an accurate quote tailored to your Lexington project, call our RESNET-certified team at 617-584-1809.
Yes. New residential construction in Lexington, MA must demonstrate energy-code compliance, and a HERS Rating is the standard path under the Massachusetts Stretch Code. Call 617-584-1809 to confirm requirements for your build.
A HERS Rating in Lexington generally involves plan review, a mid-construction inspection, and a final test with blower door and duct testing. Timing depends on your construction schedule. Reach us at 617-584-1809 to coordinate.
The Massachusetts Stretch Code sets maximum HERS index targets that vary by code version and home type, with lower scores indicating greater efficiency. Our Lexington raters help you hit the required score—call 617-584-1809.
At HERS Rating Company, we are committed to providing the highest quality energy consulting services to homebuilders, architects, and developers across Massachusetts.
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12 Pond St Ashland, MA 01721 United States
573 Washington St Quincy, MA 02169 United States
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