Great Barrington, MA Energy Code Compliance — Stretch Code & HERS Requirements (2026)
Everything a builder, architect, or homeowner in Great Barrington needs to pass the current Massachusetts energy code — explained in plain English by a certified HERS rater.
Quick Facts for Great Barrington
- Great Barrington is on the Stretch Code (225 CMR 22.00 & 23.00).
- New homes must be third-party HERS-rated and hit the index targets below.
- A blower door test (≤3.0 ACH50) and duct leakage test are required to demonstrate compliance.
- All-electric construction is strongly favored and earns a more achievable HERS target.
What Energy Code Is Great Barrington On?
Great Barrington enforces the Stretch Code of the Massachusetts energy code (225 CMR 22.00 & 23.00). The Stretch Code raises energy performance well above the base code and requires every new home to earn a verified HERS Index score through third-party testing.
Compliance is demonstrated through the HERS (Home Energy Rating System) performance pathway — the code option nearly all Great Barrington builders use — which requires a certified rater to model the design, inspect during construction, and verify final performance with diagnostic testing.
HERS Index Targets in Great Barrington
The lower the HERS Index, the more efficient the home (a HERS 0 is net-zero). Your maximum allowable score depends on the project type and whether it is all-electric or mixed-fuel:
| Project type | Mixed-fuel HERS max | All-electric HERS max |
|---|---|---|
| New single-family home | 42 | 45 |
| New home w/ solar + pre-wiring pathway | 45 | 48 |
| Addition (>1,000 sq ft) | 65 | 70 |
| Accessory Dwelling Unit (ADU) | 52 | 55–58 |
All-Electric vs. Mixed-Fuel in Great Barrington
Under the Stretch Code, Great Barrington projects choose one of two compliance tracks. All-electric buildings get a more lenient HERS target because they carry no on-site fossil-fuel combustion; mixed-fuel buildings must hit a tighter HERS score and pre-wire for future electrification.
All-Electric Path ★
- Higher (easier) HERS ceiling
- Heat pumps for heating & hot water
- No gas line / combustion safety testing
- Best long-term value in Great Barrington
Mixed-Fuel Path
- Lower (stricter) HERS ceiling
- Must pre-wire for future heat pumps
- Solar-ready + EV-ready required
- Combustion safety testing needed
Required Diagnostic Testing
Two on-site tests verify the modeled performance is real. Both must be performed and documented by a certified rater before your Great Barrington building department will sign off:
| Test | Requirement | Why it matters |
|---|---|---|
| Blower door (air leakage) | ≤ 3.0 ACH50 | Verifies the building envelope is sealed tight |
| Duct leakage (CFM25) | ≤ 4 CFM25 per 100 sq ft | Confirms conditioned air isn’t lost to unconditioned space |
The Great Barrington Compliance Path, Step by Step
How We Help Great Barrington Builders & Homeowners
We are a certified Massachusetts HERS rating company serving Great Barrington and the surrounding area. We handle the full energy-code compliance process: HERS rating & energy modeling, blower door testing, and duct leakage testing — all documented for your building department.
Quick Answers — Great Barrington Energy Code
Building in Great Barrington? Get your energy-code plan today.
Talk to a certified HERS rater about your project — no obligation.
Call (617) 571-4368