What Is a HERS Score?
A HERS score (also called a HERS Index score) is a numerical rating that measures how energy efficient your home is. The HERS Index was developed by RESNET (Residential Energy Services Network) and is the national standard for measuring home energy performance. A lower HERS score means a more energy-efficient home.
How Is the HERS Score Calculated?
The HERS score is calculated by a certified HERS Rater using energy modeling software. The rater enters your home’s specifications — insulation levels, window performance, HVAC efficiency, air leakage rate, and more — into the software, which calculates a score relative to a standard reference home. A HERS score of 100 equals the energy performance of the 2006 IECC reference home. A score of 0 is a net-zero energy home.
| HERS Score | What It Means |
|---|---|
| 0 | Net Zero Energy Home |
| 1–42 | Near Net Zero / MA Opt-In Code |
| 43–55 | MA Stretch Code Compliant (excellent) |
| 56–70 | Good energy efficiency |
| 100 | 2006 IECC Reference Home |
| 130+ | Older, energy-inefficient home |
What HERS Score Do You Need in Massachusetts?
Under the MA Stretch Code 2021, new residential construction in Massachusetts must achieve a HERS score of 55 or less. Some municipalities have adopted the optional MA Specialized Opt-In Code, which requires a HERS score of 42 or less. Mass Save new construction rebates increase as your HERS score decreases.
How to Lower Your HERS Score in Massachusetts
To achieve a lower HERS score, focus on: high levels of continuous insulation (especially in attics and walls); high-performance triple-pane windows; airtight construction (targeting 1.5–2.0 ACH50 or better); high-efficiency HVAC (heat pumps are ideal); heat recovery ventilation (HRV or ERV); and high-efficiency water heating (heat pump water heater). Your HERS Rater can model different scenarios to find the most cost-effective path to a low HERS score.
Get Your HERS Rating in Massachusetts
HERS Rating Company is a RESNET-certified HERS Rater serving all of Massachusetts. We provide energy modeling early in the design process to help you hit your target HERS score cost-effectively. Contact us for a free consultation.
Related Services in Massachusetts
HERS Rating Company is a RESNET-certified, Mass Save-approved HERS Rater serving all 351 Massachusetts cities and towns.
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HERS Score Explained for Massachusetts New Construction
A HERS score measures home energy efficiency: 100 = reference home, lower is better. MA Stretch Code 2021 requires HERS 55 or below for single-family homes. The Specialized Stretch Code requires HERS 42 or below. Net-zero homes achieve HERS 0. HERS Rating Company performs all energy modeling and testing to determine your home’s HERS score.
How to Achieve a Low HERS Score in Massachusetts
Key factors: insulation levels (R-49 attic minimum), air sealing (target under 2.0 ACH50), efficient HVAC (heat pumps score well), tight duct systems (under 4% leakage), and high-performance windows. HERS Rating Company provides a pre-construction plan review to help optimize your HERS score before breaking ground. Call 617-584-1809.