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Home Energy Rating System (HERS Rating) & Stretch Energy Code

The Stretch Code (Massachusetts Stretch Energy Code – 780 CMR Appendix 120AA) mandates that homes larger than 3,000 square feet achieve a Home Energy Rating System (HERS) rating of 65 or less. HERS is designed so that houses built to the standard building code achieve a rating of about 100 (the base code in Massachusetts yields a bit below 100), so a 65 means that the home is about 35% more efficient than a similarly sized home built to base code levels. Homes smaller than 3,000 square feet must achieve a score of 70 or better.

For additions and major renovations, the requirement is a HERS 80 for buildings (or individual units in multi-unit buildings) bigger than 2,000 square feet, and 85 for those less than 2,000 square feet.

Complete HERS Rating including

  • Projected Rating – this is done from building plans and supplied material data to determine if the home/building will meet the Stretch Code, other applicable code requirements (IECC 2012) or energy efficiency goals.
  • Site Review – on-site visual inspection (pre-drywall) of all systems, material, installation quality of insulation as well as modify rating based on any changes made from original plan information.
  • Confirmed Rating – upon full completion of the home/addition a performance test is performed including Blower Door Pressure Test and Duct Air Leakage Testing. This test data is entered into the model and a Confirmed HERS Rating is provided to confirm the home/building did meet the Stretch Code, other applicable code requirements (IECC 2012) or energy efficiency goals.

Prescriptive Ratings are also available utilizing RESCheck software to help remodeling projects meet the code requirements.

What is the HERS Index

The HERS Index is a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2004 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home's score the more energy efficient it is in comparison to the HERS Reference Home.

Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 80 is 20% more energy efficient.

Stretch Energy Code Towns (Map)

Stretch Energy Code Summary

Stretch Energy Code Q & A

HERS Index Chart

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