Stretch Energy Code

Chapter 115 Appendix AA of the Massachusetts State Building Code (MSBC) is referred to as the Stretch Energy Code and was created by the Massachusetts Board of Building Regulations and Standards (BBRS) in 2008. The Stretch Code provides the option for cities and towns to adopt a more stringent energy code that requires greater energy efficiency in buildings than the mandatory statewide base code.

On December 21, 2009, the Cambridge City Council voted to adopt the Stretch Energy Code. The higher energy efficiency standards went into effect on July 1, 2010. Cambridge was one of the first municipalities in the state to adopt the Stretch Energy Code, which has been adopted by 207 municipalities as of September 17, 2017.

The most recent amendments made to Chapter 13, Chapter 51, and Chapter 115 Appendix AA of the MSBC 8th Edition went into effect on January 1, 2017. These amendments upgraded Chapters 13 and 51 to the latest currently reference the IECC 2018 and ASHRAE 90.1-2013 energy standards.


  • Large area buildings over 100,000 square feet, as well as new supermarkets, laboratories, and conditioned warehouses over 40,000 square feet, must now demonstrate energy use per square foot of at least 10% below the energy requirements of ANSI/ASHRAE/IESNA 90.1—2013 Appendix G Performance Rating Method on either a site or source energy basis.
  • All other buildings are required to follow either Chapter 13 or Chapter 51 of the MSBC as applicable based on the use and occupancy of the building. See the "Commercial Buildings FAQ" document below for more information.
  • For residential buildings, the Stretch Energy Code also requires building owners to perform an Energy Rating Index (ERI) analysis using one of the approved pathways. See the "Residential Buildings FAQ" document below for more information.

Additional Resources

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