A home’s airtightness is one of the most significant factors influencing its HERS Score. Air leakage increases heating and cooling loads, reduces comfort, and makes mechanical systems work harder—especially in New England’s cold climate.
Blower Door Testing quantifies this leakage and directly impacts the energy model used to determine your final HERS Rating.
How Air Leakage Affects Energy Efficiency
Uncontrolled air leakage leads to:
- Higher heating and cooling costs
- Drafts and uneven temperatures
- Moisture intrusion risks
- Reduced HVAC efficiency
- Poor indoor air quality
Explore details on blower door testing here:
What Is a Blower Door Test?
Airtightness in the HERS Model
The HERS Index uses Blower Door Test data (ACH50) to calculate:
- Envelope performance
- Heating/cooling loads
- Ventilation requirements
- Overall energy usage
Learn how the rating is determined:
Understanding Your HERS Score
Required Airtightness Levels in MA & RI
Massachusetts
- Base Code: ≤ 3 ACH50
- Stretch Code: ≤ 3 ACH50 (lower for high-performance homes)
Rhode Island
- RI IECC 2024: ≤ 3 ACH50
Learn more:
Blower Door Testing for Code Compliance
Improving Airtightness Before Testing
Energy Geeks may recommend:
- Sealing gaps around penetrations
- Weatherstripping exterior doors
- Sealing attic and basement bypasses
- Improving insulation installation
- Duct sealing (if applicable)
Learn how preparation works:
Test Preparation & What to Expect
