COMMONWEALTH OF MASSACHUSETTS
EXECUTIVE OFFICE OF
ENERGY AND ENVIRONMENTAL AFFAIRS
DEPARTMENT OF ENERGY RESOURCES
100 CAMBRIDGE ST., SUITE 1020
BOSTON, MA 02114
Telephone: 617-626-7300
Facsimile: 617-727-0030
Charles D. Baker Kathleen A. Theoharides
Governor Secretary
Karyn E. Polito Patrick C. Woodcock
Lt. Governor Commissioner
VIA EMAIL
September 22, 2022
To: Clerk of the House of Representatives
CC: Chairs of the Joint Committee on Telecommunications, Utilities, and Energy
RE: Submission of amended Stretch Energy Code – 225 CMR 22.00 and 225 CMR 23.00 to
General Court
Dear Clerk:
Pursuant to M.G.L. Chapter 25A Section 12, please find enclosed:
225 CMR 22.00 and 23.00 – Stretch Energy Code Regulations
Summary of the amended Regulations in layperson's terms
In the development of 225 CMR 22.00 and 225 CMR 23.00, the pertinent provisions of Chapter
30A, except section five, have been complied with.
In addition to the requirements of Section 12, the Department of Energy Resources has made
additional information, including a red-line version of the regulations, available to the public.
That information is accessible through the Department’s website:
https://www.mass.gov/info-details/stretch-energy-code-development-2022
Please direct questions and comments on this regulation to:
Johannes Buchanan
Assistant Secretary for Government Affairs and Community Relations, Executive Office of
Energy and Environmental Affairs
Johannes.K.Buchanan2@mass.gov
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Sincerely,
s/Patrick C. Woodcock
Patrick C. Woodcock
Commissioner
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Summary of Proposed New 225 CMR 22.00 and 23.00 (Updated September 22, 2022)
2023 Stretch Energy Code Update and Municipal Opt-in Specialized Code
1. Background
The Stretch energy code (Stretch Code) regulations have since 2009 been published in MA
780CMR chapters 115.aa and previously 780 CMR 110.aa under the jurisdiction of the Board of
Building Regulations and Standards. The climate act of 2021 moved the authority for the Stretch
Code promulgation to the Department of Energy Resources (DOER) and at the same time
required the development of a new Municipal Opt-in Specialized energy code (Specialized
Code). These appear as new regulations in 225 CMR 22.00 and 225 CMR 23.00.
CMR 22.00 covers Residential low-rise construction and
CMR 23.00 covers Commercial and all other construction (including most multi-family).
This document provides an overview and explanation of these draft regulations. In the following
sections, this document summarizes:
Section 1: Background and Timeline.
Section 2: Structure.
Section 3: Stretch Code. The modifications to the Base Energy Code that form the
Stretch Code amendments in Residential Low Rise (Section 3.A) and Commercial and all
other buildings (Section 3.B).
Section 4: Specialized Opt-in Code. The modifications to the Stretch Code that form the
Specialized Code appendices in Residential Low Rise (Section 4.C) Commercial and all
other buildings (Section 4.D).
1.1 Timeline for Stretch and Specialized Code adoption
The Stretch code has been available since late 2009 and has already been widely adopted by
cities and towns in Massachusetts. As a result, the update to the Stretch code will not require an
additional bylaw vote in those existing Stretch code municipalities, some of whom are on their
3rd update already. The Specialized code is a new option and is adopted as a municipal opt-in
code similar to the Stretch code process. Cities and towns seeking to adopt will require an active
vote by City council or Town meeting to opt-in to the Specialized Code.
1.2 Energy code options
The current energy code options in Massachusetts are as follows:
Current Base Energy Code = IECC 2018 with MA amendments
Current Stretch Code = IECC 2018 with MA amendments + Stretch Code amendments
The current Base Energy Code is being updated along with the rest of the BBRS regulated
building codes to a 10th edition MA code that will be based on the International Code Council
(ICC) 2021 edition. Combined with the Stretch Code update and new Specialized Code
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contained in DOER’s proposed regulations, this results in a tiered set of 3 energy code options
for municipalities as follows:
Updated Base Energy Code = IECC 2021 with MA amendments
Updated Stretch Code = IECC 2021 with MA amendments + Stretch Code amendments
Specialized Code = IECC 2021 with MA amendments + Stretch Code amendments +
Specialized Code appendices
2. Structure
The updated Stretch Code as newly incorporated into DOER regulations (225 CMR) is divided
into 2 chapters, following the format of the IECC.
A. 225 CMR 22 - Residential Low-rise Construction Stretch Energy Code
B. 225 CMR 23 - Commercial (and all other) Construction Stretch Energy Code
The Specialized Code includes additional requirements that form an Appendix to each of the
chapters of the Stretch Code.
C. 225 CMR 22 Appendix RC – Residential Low-rise Construction Specialized Code
D. 225 CMR 23 Appendix CC – Commercial (and all other) Construction Specialized Code
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3. Stretch Code Summary
A. 225 CMR Chapter 22: Residential Low-Rise Construction Stretch Code
Code Compliance Pathways
The current Base Energy Code for residential low-rise construction allows 3 different pathways
for code compliance. The current Stretch Code requires code compliance through 2 of those
pathways:
A1. Home Energy Rating Scores (HERS) index certification
A2. Passive house certification
The updated Stretch Code maintains these 2 pathways for compliance, but amends certain
requirements in the HERS (Section R406) and Passive house (Section R405)1 pathways.
A1. HERS Pathway (Section R406)
The updated Stretch Code lowers the maximum allowable HERS ratings to reflect improvements
in energy efficiency as shown in Table 1 below.
TABLE 1: CHANGES TO MAXIMUM HERS INDEX (SEE TABLE R406.5)
Maximum HERS Index score (before renewable energy credit)
Alterations, Additions and
New construction Change of use
Updated Updated Current Stretch Updated Current Stretch
Stretch Stretch Code Code Stretch Code
On-site Clean
Code July 1, (Same as Code
Energy
2024 base code)
Application
None (Fossil 52 55 52 65
fuels) 42
Solar 55 60 55 70
All-Electric 55 60 55 70
Solar & All- 45
58 65 58 75
Electric
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1Key sections of the Stretch Code and Specialized Code are referenced in parentheses based on their IECC section
number. For example: Updated HERS ratings (Section R406).
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As shown in Table 1, the current Stretch Code allows a 5-point higher HERS rating for homes
using heat pumps for space and water heating compared to homes using fossil fuels (natural gas,
propane or heating oil) for space heating.
The updated Stretch Code maintains differential HERS ratings, and after a phase-in period until
July 1, 2024 requiring HERS 45 for all-electric homes and HERS 42 for homes with any use of
fossil fuels (Section R406.5). The updated Stretch Code is simplified and emphasizes energy
efficiency and electrification by dropping the 5 HERS point credit for rooftop solar and 2 HERS
point credit for solar thermal in the current Stretch Code.
The updated Stretch Code also updates HERS requirements for alterations, additions and change
of use for existing homes. Additional detail on alterations, additions and change of use can be
found in A5 below (Section R503.1.5).
A2. Passive House Pathway (Section R405)
Passive House certification is an optional code compliance pathway in the Base Energy Code
and the current Stretch Code. The current Base Energy Code and current Stretch Code allow
certification through the Passive House Institute US (Phius) Phius+ 2018 standard or the Passive
House International (PHI) standard. The updated Base Energy Code and updated Stretch Code
will align with the most recent Phius standards, allowing the Phius CORE 2021 standard
(efficiency) or the Phius ZERO 2021 standard (efficiency and renewables). The PHI standard
remains unchanged as an option.
New Residential Stretch Code Requirements
A3. Energy or heat recovery ventilation (Section R403.6.1)
The updated Stretch Code adds ventilation requirements through either heat recovery or energy
recovery to the HERS Pathway. There is no change to the Passive house Pathway because heat
or energy recovery is already required.
A4. Wiring for Electric Vehicle (EV) charging (Section R404.4)
The proposed updated Base Energy Code requires at least 1 space per home or a minimum of
10% of spaces in a new multi-family parking lot be provided with electric wiring to allow for
future EV charging. The updated Stretch Code requires the same 1 space per home and increases
the requirement to a minimum of 20% of spaces in a new multi-family parking lot.
A5. Existing buildings: Alterations, Additions and Changes of use (Section R503.1.5)
The updated Stretch Code clarifies when alterations to existing homes trigger compliance with
different requirements. The requirements are as follows:
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Additions over 1,000 square feet (sf) must follow the HERS Pathway and meet the HERS
requirements for Additions in Table 1 above. Additions under 1,000 square feet will
continue to follow Base Energy Code.
Additions that exceed 100% of the conditioned floor area of the existing dwelling unit
(ie. more than double the size of the house) must follow the HERS Pathway and meet the
HERS requirements for Additions in Table 1 above.
Level 3 Alterations (over 50% of the home is renovated and reconfigured) as defined in
the International Existing Building Code (IEBC 2021) must meet the HERS requirements
in Table 1 above. Level 1 and Level 2 alterations will continue to follow the Base Energy
Code.
B. 225 CMR chapter 23: Commercial (all other) Stretch Code amendments
Code Compliance Pathways
The current Base Code for commercial construction has multiple code compliance pathways
from the IECC as well as the ASHRAE 90.1 standard. The current Stretch Code requires a 10%
improvement over the ASHRAE 90.1 Appendix G pathway for buildings over 100,000-sf (limit
is 40,000-sf for labs, hospitals, supermarkets, refrigerated warehouses and data centers) but
allows smaller commercial buildings to choose from the other Base Code IECC pathways.
The updated Stretch Code includes 5 code pathways for new construction. These new
requirements will go into effect on the following schedule:
1. All non-residential commercial buildings: any building applying for permit on or after
July 1, 2023 subject to updated stretch code provisions
2. Multi-family commercial buildings follow schedule below:
Updated Stretch Code Updated Stretch Code
July 1, 2023 through Beginning July 1, 2024
June 30, 2024
Targeted Performance Optional Optional
HERS Optional HERS 52/55 Optional HERS 42/45
Passive House Optional Optional
Relative Performance Optional Not allowed
Allowable use of each pathway is based on the type of building, with 4 major categories of
buildings:
B1. TEDI Pathway: Offices, residential, and schools over 20,000-sf are required to use a new
Thermal Energy Demand Intensity (TEDI) Pathway. The updated Stretch Code sets forth
specific TEDI limits by building type. This uses the same energy software tools as the current
ASHRAE 90.1 Appendix G pathway but with significantly more focus on heating, cooling and
the building envelope. Building uses adjacent to office and residential use, such as post offices,
town hall, and other similar buildings are also covered under this pathway.
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B2. 10% better than ASHRAE Appendix G: High ventilation buildings such as labs and
hospitals can continue to use a 10% better than ASHRAE appendix G pathway or opt to use the
TEDI pathway. Multi-family buildings may follow the ASHRAE appendix G pathway until July
1, 2024. The updated Base Code and updated Stretch Code change the underlying ASHRAE
standard 90.1 to the more recent 2019 edition.
B3. Prescriptive pathway: Small commercial buildings (any building use except multi-family)
under 20,000-sf will be able to continue to comply through an updated prescriptive pathway, or
can opt to use the TEDI pathway. The prescriptive pathway is being updated in the Base Energy
Code, and the updated Stretch Code includes additional amendments to improve efficiency
beyond Base Energy Code for small buildings.
B4. HERS and Passive House: Multi-family buildings larger than those covered by the
residential low-rise code can choose between HERS and Passive House pathways that contain
the same energy efficiency requirements as the updated Residential low-rise Stretch Code. The
Passive House certification options remain available as an option for all building types.
Mixed-use buildings can use a combination of code pathways as appropriate for different
portions of the building, or choose a whole-building approach through the TEDI or Passive
House pathways.
Additional Commercial energy efficiency requirements:
B5. Efficient electrification (Section C401.4)
The updated Stretch Code mandates partial electrification of space heating for highly ventilated
buildings which follow the ASHRAE Appendix G compliance pathway. The updated Stretch
Code mandates full electrification of space heating for buildings not following the ASHRAE
pathway which choose to utilize the less stringent curtainwall envelope UA2 performance option
(See B6 below).
B6. Mandatory envelope “Area-weighted U value2 (Section C402.1.5) (btu/hr-sf-F) of an
envelope section
The proposed Base Code and updated Stretch Code updates and simplifies the existing
mandatory envelope UA provisions that are currently in the MA Base Code and Stretch Code.
Mandatory area-weighted U value provisions replace UA provisions and are simplified and
strengthened compared to existing provisions for all buildings not using curtain wall. Mandatory
area-weighted U value provisions remain at the same stringency as existing provisions for
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2‘Area-weighted U value’ designates the average effective insulation level measured by the ‘U’ value across an
exterior area ‘A’ of multiple elements (walls, windows, doors, etc).
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curtain wall buildings. However, buildings which opt for the curtainwall U value limit are
required to have full efficient electrification of space heating (see B5 above).
B7. Air leakage (Section C402.5)
The updated Stretch Code strengthens the air leakage limit compared to the updated Base Energy
Code. Code language of this section adopts proposed IECC 2024 language which clarifies
requirements.
B8. Thermal bridges (Section C402.7)
Thermal bridge accounting is added to the updated Stretch Code to more accurately represent the
insulation performance of a fully constructed wall or building envelope. Prescriptive and tailored
accounting approaches are available.
B9. Economizers (Section 403.5)
Economizer requirements (which permit the use of outside air for free night-time cooling) are
expanded in the updated Stretch Code compared to the updated Base Energy Code.
B10. Ventilation energy recovery (Section C403.7)
Ventilation energy recovery requirements are strengthened in the updated Stretch Code
compared to the updated Base Energy Code. New provisions are also added to better
accommodate high ventilation buildings and toxic exhaust requirements.
B11. Wiring for Electric Vehicle (EV) charging (Section C405.13)
The updated Base code requires wiring for future EV charging to 10% of new parking spaces.
The updated Stretch Code raises the minimum number of spaces requiring EV wiring to 20% in
Group R and B occupancies3, with 10% for all other occupancies. EV charging can be met with
either dedicated electric branch circuits, or with an automatic load management service (ALMS)
that allows multiple spaces to be served by a higher amperage circuit, thus improving overall
charging capacity at a lower installed cost.
B12. Additional efficiency requirement (Section C406)
Section C406 in the base code mandates certain additional efficiency measures, allowing
designers to choose from a number o