HERS Rating in Marion, MA — Requirements, Index Targets & RESNET Process (2026)
What a HERS rating is, when Marion requires one, the Index score you must hit, and exactly how the rating is performed — from a certified RESNET HERS rater.
A Home Energy Rating System (HERS) rating measures a home’s energy efficiency on a scale where a standard new home scores 100 and a net-zero home scores 0 — lower is better. Marion, MA uses a certified HERS rating to verify energy-code compliance for new construction and major renovations, and to qualify for Mass Save® incentives under the Massachusetts base energy code.
Required HERS scores in Marion: new mixed-fuel (gas) homes must reach HERS 42 or lower; new all-electric homes HERS 45 or lower; additions & major renovations 65 (mixed-fuel) / 70 (all-electric); ADUs 52 / 55.
HERS Rating Quick Facts — Marion
- A HERS Index scores a home’s energy performance: lower is better, 0 = net-zero, 100 = a 2006-code reference home.
- In Marion a third-party HERS rating is required by code.
- The rating is performed by a certified RESNET HERS rater — not the builder or code official.
- It involves energy modeling, at least one rough inspection, and final diagnostic testing (blower door + duct leakage).
What Is a HERS Rating?
The Home Energy Rating System (HERS) Index is the national standard, administered by RESNET, for measuring a home’s energy efficiency. A certified rater builds an energy model of the home, verifies insulation and air-sealing during construction, and performs diagnostic tests at completion. The result is a single number — the HERS Index — that Marion building officials, lenders, and incentive programs use to confirm performance.
HERS Index Targets for Marion
Because Marion has adopted the Stretch Code, new homes must be HERS-rated and meet these maximum Index scores:
| Project type | HERS Index target | Notes |
|---|---|---|
| New single-family home (mixed-fuel) | ≤ 42 | Verified by RESNET rater |
| New single-family home (all-electric) | ≤ 45 | More achievable target |
| Addition > 1,000 sq ft | ≤ 65–70 | Performance path |
| Accessory Dwelling Unit | ≤ 52–58 | By ADU type |
The RESNET Rating Process, Step by Step
Every Marion HERS rating we perform follows the same RESNET-accredited workflow:
1. Design & Modeling
- Review plans & specs
- Build the energy model
- Confirm the design hits target
2. Rough Inspection
- Insulation & air-barrier check
- Before drywall
- Photo documentation
3. Final & Testing
- Blower door test
- Duct leakage test
- Registered HERS certificate
Sampling & When a Rating Is Required in Marion
A HERS rating is triggered for new residential construction, additions over 1,000 sq ft, and many ADUs under the Stretch Code. For multi-unit and production projects, RESNET sampling protocols can allow one rated home to represent a set — we’ll advise whether your Marion project qualifies.
Documentation You Receive
At completion we register the rating with RESNET and provide the signed HERS certificate, the rating report, and the diagnostic test results your Marion building department and incentive programs require. Need the tests on their own? See our Marion blower door testing and duct leakage testing, or the full Marion energy code overview.
Quick Answers — Marion HERS Rating
Need a HERS rating in Marion?
Talk to a certified Massachusetts HERS rater and get a free, no-obligation quote.
Call (617) 571-4368 Get a Free Quote