225 CMR 22 MA Residential low-rise Front end amend Clean 12-8-22 — File 22-0084

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 1 | P a g e Massachusetts Stretch Code and Specialized Code for Low-Rise Residential (Note: please see 225 CMR 23 for Commercial, Multi-family and all other construction) The Massachusetts Stretch energy code (Stretch Code) first became available for municipal adoption in 2009 as Appendix 110.aa and then 115.aa as part of the building code in 780 CMR. In 2021 the Massachusetts legislature passed new legislation moving authority for updates to the Stretch Code to the Department of Energy Resources and 225 CMR. This code takes effect on January 1, 2023 and is designed to align with the forthcoming MA 10th edition building code promulgated under 780 CMR. Building permit applications for projects received on or after Jan. 1, 2023 in Stretch Code communities shall comply with this code. As with the 10th edition building code, this energy code is based on modified versions of the 2021 code books as published by the International Code Council (ICC). Specifically, the 2021 International Energy Conservation Code (IECC 2021) as amended. This section (225 CMR 22) covers low-rise residential buildings. All other buildings are covered by 225 CMR 23. 225 CMR 22 and 23 in combination form the Stretch Code – and must be adopted together and not in part. Municipalities may also elect to adopt the combination of Appendix RC of 225 CMR 22 (Low rise residential) and Appendix CC of 225 CMR 23 (all other buildings) which together form the Municipal Opt-in Specialized code (Specialized Code). For communities that have adopted the Stretch Code, the following 225 CMR 22 amendments to the IECC 2021 apply together with 225 CMR 23 for all other buildings. For communities that adopt the Specialized Code, the following 225 CMR 23 amendments apply in combination with Appendix RC, along with 225 CMR 23 and Appendix CC for all other buildings. In both the Stretch Code and the Specialized Code these amendments to the IECC 2021 replace Chapter 13 – Energy Efficiency of 780 CMR in the Base energy code. Please remember that the Massachusetts amendments posted online are unofficial versions that are made available for convenience. Official versions of the Massachusetts amendments may be purchased from the State House Bookstore at www.sec.state.ma.us/spr/ and the IECC 2021 can be purchased from the ICC at www.iccsafe.org

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 2 | P a g e 225 CMR 22: MASSACHUSETTS FRONT-END AMENDMENTS TO THE INTERNATIONAL ENERGY CONSERVATION CODE 2021 MASSACHUSETTS STRETCH ENERGY CODE – 2023 Residential low-rise amendments to IECC2021 IECC 2021 and IRC 2021 CHAPTER 11: ENERGY EFFICIENCY CHAPTER 1 [RE] SCOPE AND ADMINISTRATION SECTION R103 CONSTRUCTION DOCUMENTS R103.2 Insert after Subsection R103.2(9) the following: 10. EV Ready Space locations per R404.4. 11. Solar-Ready Zone in accordance with Appendix RB, or Solar Zone Area when complying with Appendix RC for mixed-fuel buildings. CHAPTER 2 [RE] DEFINITIONS R202 GENERAL DEFINITIONS R202 Add the following definitions: ALL-ELECTRIC BUILDING. A building with no on-site combustion equipment for fossil fuel use or capacity including fossil fuel use in space heating, water heating, cooking, or drying appliances. CLEAN BIOMASS HEATING SYSTEM. Wood-pellet fired central boilers and furnaces where the equipment has a thermal efficiency rating of 85% (higher heating value) or greater; and a particulate matter emissions rating of no more than 0.08 lb. PM2.5/MMBtu heat output. COMBUSTION EQUIPMENT. Any equipment or appliance used for space heating, service water heating, cooking, clothes drying and/or lighting that can use fuel gas, fuel oil or solid fuel and that is not a clean biomass heating system. ELECTRIC VEHICLE. An automotive-type vehicle for on-road use, such as passenger automobiles, buses, trucks, vans, neighborhood electric vehicles, electric motorcycles, and the like, primarily powered by an electric motor that draws current from a rechargeable storage battery, fuel cell, photovoltaic array, or other source of electric current. Informational Note: defined as in 527 CMR 12.00: Massachusetts Electrical Code (Amendments) section 625.2.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 3 | P a g e ELECTRIC VEHICLE SUPPLY EQUIPMENT (EVSE). The conductors, including the ungrounded, grounded, and equipment grounding conductors, and the Electric Vehicle connectors, attachment plugs, and all other fittings, devices, power outlets, or apparatus installed specifically for the purpose of transferring energy between the premises wiring and the Electric Vehicle. Informational Note: defined as in 527 CMR 12.00: Massachusetts Electrical Code (Amendments) section 625.2. ELECTRIC VEHICLE READY PARKING SPACE (“EV Ready Space”). A designated parking space which is provided with wiring and electrical service sufficient to provide 240 volt AC level II or equivalent EV charging, as defined by Standard SAE J1772 for EVSE servicing light duty Electric Vehicles. ENTHALPY RECOVERY RATIO. Change in the enthalpy of the outdoor air supply divided by the difference between the outdoor air and entering exhaust air enthalpy, expressed as a percentage. HIGH-EFFICACY LAMPS. Light-emitting diode (LED) lamps with an efficacy of not less than the following: 1. 60 lumens per watt for lamps over 40 watts. 2. 50 lumens per watt for lamps over 15 watts to 40 watts. 3. 45 lumens per watt for lamps 15 watts or less. MIXED-FUEL BUILDING. A building that contains combustion equipment or includes piping for such equipment. POTENTIAL SOLAR ZONE AREA. The combined area of any flat roofs, or low-sloped roofs and any steep-sloped roofs oriented between 90 degrees and 300 degrees of true north where the annual solar access is 70 percent or greater. Annual solar access is the ratio of “annual solar insolation with shade” to the “annual solar insolation without shade”. Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access. CHAPTER 3 [RE] GENERAL REQUIREMENTS SECTION R301 CLIMATE ZONES R301 Replace Section R301 as follows: R301.1 General. Massachusetts is in climate zone 5A CHAPTER 4 [RE] RESIDENTIAL ENERGY EFFICIENCY

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 4 | P a g e SECTION R401 GENERAL R401 Replace Section R401.1 and R401.2 as follows: R401.1 Scope. This chapter applies to residential buildings. Municipalities which have adopted the Stretch Energy Code shall use the energy efficiency requirements of this chapter, or Chapter 51 where applicable for existing buildings. Municipalities which have adopted the Municipal Opt-in Specialized Stretch energy code shall comply with R401.2.4 including both the requirements of Appendix RC and this chapter. R401.2 Application. Residential buildings shall comply with Section R401.2.5 and either Sections R401.2.2, R401.2.3 or R401.2.4. R-use buildings without individually separate dwelling units (such as single-room occupancy buildings) may comply with Section R401.2.1. The option selected for compliance shall be identified in the certificate required by Section R401.3. Exception: Additions under 1,000 sf, level 1 and level 2 alterations, and repairs to existing buildings complying with Chapter 5 [RE]. R401.2.1 Prescriptive Compliance Option. The Prescriptive Compliance Option requires compliance with Sections R401 through R404, R408 and Appendix RB. R401.2.2 Passive House Building Certification Option. The Passive House Building Certification Option requires compliance with Section R405, R404.4 and Appendix RB. R401.2.3 Energy Rating Index Option. The Energy Rating Index (ERI) Option requires compliance with Section R406, R403.6, R404.4 and Appendix RB. R401.2.4 Appendix RC. Residential Buildings and dwelling units covered by this chapter may elect to comply with the requirements of Appendix RC and R404 as amended. R401.2.5 Additional energy efficiency. This section establishes additional requirements applicable to all compliance approaches to achieve additional energy efficiency. 1. For buildings complying with Section R401.2.1, two of the additional efficiency package options shall be installed according to Section R408.2. 2. For buildings electing to be all-electric buildings, both R408.2.2 and R408.2.3 shall apply for primary space heating and domestic hot water supply. R402.1.5.1 Add Subsection R402.1.5.1 as follows: R402.1.5.1 Approved software for Total UA alternative: The following software is approved for demonstrating Total UA compliance: REScheck-Web for IECC2021 Massachusetts stretch code available at http://www.energycodes.gov/rescheck

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 5 | P a g e R402.4.1.1 Modify Table R402.4.1.1 to amend the Insulation Installation Criteria as follows: TABLE R402.4.1.1 AIR BARRIER AND INSULATION INSTALLATION COMPONENT AIR BARRIER CRITERIA INSULATION INSTALLATION CRITERIA General requirements A continuous air barrier shall be installed in the building envelope. Breaks or joints in the air barrier shall be sealed. All insulation shall be installed at Grade I quality in accordance with ICC/RESNET 301. Air-permeable insulation shall not be used as a sealing material. R403.3.5 Insert the following to the end of Subsection R403.3.5: Postconstruction or rough-in testing and verification shall be done by a HERS Rater, HERS Rating Field Inspector, or an applicable BPI Certified Professional. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. R403.6 Replace Section R403.6 as follows: R403.6 Mechanical ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating. Each dwelling unit of a residential building shall be provided with a continuously operating mechanical balanced ventilation system that has been site verified to meet a minimum airflow per either: 1. RESNET HERS Index in accordance with RESNET/ICC Standard 301, or 2. ASHRAE Standard 62.2-2019 or 62.2-2022, or 3. the following formula for one- and two-family dwellings and townhouses of three or less stories above grade plane: Q = .03 x CFA + 7.5 x (Nbr +1) - 0.052 x Q50 x S x WSF Where: CFA is the conditioned floor area in sq ft Nbr is the number of bedrooms Q50 is the verified blower door air leakage rate in cfm measured at 50 Pascals S is the building height factor determined by this table: stories above grade plane 1 2 3 S 1.00 1.32 1.55 WSF is the shielded weather factor as determined by this table:

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 6 | P a g e County WSF Barnstable 0.60 Berkshire 0.52 Bristol 0.54 Dukes 0.59 Essex 0.58 Franklin 0.52 Hampden 0.49 Hampshire 0.59 Middlesex 0.55 Nantucket 0.61 Norfolk 0.52 Plymouth 0.53 Suffolk 0.66 Worcester 0.59 R403.6.1 Replace Subsection R403.6.1 and Subsections R403.6.1.1 and R403.6.1.2 as follows: R403.6.1 Heat or Energy Recovery Ventilation. Heat or energy recovery balanced ventilation systems shall be provided for dwelling units as specified in either Section R403.6.1.1 or R403.6.1.2, as applicable. R403.6.1.1 Large Systems. Systems with a rated airflow exceeding 300 cfm shall have an enthalpy recovery ratio of not less than 50 percent at cooling design condition and not less than 60 percent at heating design condition, determined in accordance with AHRI 1060 at an airflow not less than the design airflow. R403.6.1.2 Other Systems. Systems with a rated airflow of 300 cfm or less shall have a sensible recovery efficiency (SRE) of not less than 65 percent at 32°F (0°C) at an airflow not less than the design airflow. SRE shall be determined in accordance with CAN/CSA-C439 and shall be listed. Linear interpolation of listed values for SRE shall be permitted. R403.6.3 Replace R403.6.3 as follows: R403.6.3 Testing and Verification. Installed performance of the mechanical ventilation system shall be tested and verified by a HERS Rater, HERS Rating Field Inspector, or an applicable BPI Certified Professional, and measured using a flow hood, flow grid, Residential IAQ Fault Indicator Display certified to the California Energy Commission, or other airflow measuring device in accordance with either RESNET Standard 380 or ACCA Standard 5. R403.6.4 – R403.6.7 Add Subsections R403.6.4 – R403.6.7 as follows:

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 7 | P a g e R403.6.4 Air-moving equipment, selection and installation. As referenced in ASHRAE Standard 62.2, Section 7.1, ventilation devices and equipment shall be tested and certified in accordance with HVI 920 (Home Ventilating Institute), or equivalent, and the certification label shall be found on the product. Installation of systems or equipment shall be carried out in accordance with manufacturers’ design requirements and installation instructions. Where multiple duct sizes and/or exterior hoods are standard options, the minimum size shall not be used. R403.6.5 Sound Rating. Sound ratings for fans used for whole building ventilation shall be rated at a maximum of 1.0 sone. Exception: HVAC air handlers and remote-mounted fans need not meet sound requirements. There must be at least 4ft of ductwork between the remote-mounted fan and intake grille. R403.6.6 Documentation. The owner and the occupant of the dwelling unit shall be provided with information on the ventilation design and systems installed, as well as instructions on the proper operation and maintenance of the ventilation systems. Ventilation controls shall be labeled with regard to their function, unless the function is obvious or unless the function is communicated through a digital user interface provided with the control. R403.6.7 Air Inlets and Exhausts. All ventilation air inlets shall be located a minimum of 10ft from vent openings for plumbing drainage systems, appliance vent outlets, exhaust hood outlets, vehicle exhaust, or other known contamination sources; and shall not be obstructed by snow, plantings, or any other material. Outdoor forced air inlets shall be covered with rodent screens having mesh openings not greater than ½ inch. A whole house mechanical ventilation system shall not extract air from an unconditioned basement unless approved by a registered design professional. Where wall inlet or exhaust vents are less than seven (7) feet above finished grade in the area of the venting, including but not limited to decks and porches, a metal or plastic identification plate shall be permanently mounted to the exterior of the building at a minimum height of eight (8) feet above grade directly in line with the vent terminal. The sign shall read, in print size no less than one-half (1/2) inch in size, "MECH. VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS". Exceptions: 1. Ventilation air inlets in the wall ≥ 3 ft. from dryer exhausts and contamination sources exiting through the roof. 2. No minimum separation distance shall be required between local exhaust outlets in kitchens/bathrooms and windows. 3. Vent terminations that meet the requirements of the National Fuel Gas Code (NFPA 54/ ANSI Z223.1) or equivalent. R404.4 Add Section R404.4 and Table R404.4 as follows:

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 8 | P a g e R404.4 Wiring for Electric Vehicle Ready Parking Spaces (“EV Ready Spaces”). EV Ready Spaces shall be provided in accordance with Table R404.4. The dedicated branch circuit shall be identified as “EV READY” in the service panel or subpanel directory, and the termination location shall be marked as “EV READY”. The circuit shall terminate in a NEMA receptacle or a Society of Automotive Engineers (SAE) Standard SAE J1772 electrical connector for EVSE servicing Electric Vehicles, located within 6 feet (1828 mm) of each EV ready space. Conductors and outlets for EVSE shall be sized and installed in accordance with the MA electrical code. TABLE R404.4 EV READY PARKING SPACE REQUIREMENTS Type of Building Number of parking spaces 1 & 2 family dwellings and town homes At least 1 50-amp branch circuit per dwelling unit to provide for AC Level II charging All other R-use buildings At least 20% of spaces served with a 40-amp, 208/240-volt circuit with a minimum capacity of 9.6 kVA. Exceptions: 1. In no case shall the number of required EV Ready Spaces be greater than the number of parking spaces installed. 2. This requirement will be considered met if all spaces which are not EV Ready are separated from the premises by a public right-of-way. 3. R-2 multi-family properties may elect to comply with Commercial EV ready requirements in C405.13. 4. One or more SAE Level II spaces may be substituted with multiple SAE Level I spaces provided with wiring for a minimum 20amp, 120 volt EVSE, with a ratio of at least 3 Level I spaces for each Level II space required. R405. Replace Section R405 in its entirety as follows: Section R405 Passive House Building Certification Option. R405.1 Compliance. Projects may document compliance with either Phius certification in accordance with R405.2 or PHI certification in accordance with R405.3. Projects pre-certified as meeting the Phius CORE 2021 or Phius ZERO 2021 Passive Building Standard – North America, or newer, demonstrated using approved software by Phius, where Phius design-certification is demonstrated by Phius and a Certified Passive House Consultant (CPHC); or, Projects pre-certified as meeting the Certified Passive House standard using the current software and program criteria by the Passive House Institute (PHI), where PHI certification is demonstrated by a Certified Passive House Designer and a Certified Passive House Certifier.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 9 | P a g e R405.2 Phius Documentation. When using WUFI Passive or other Phius approved software: 1. Prior to the issuance of a building permit, the following items must be provided to the Building Official: a. A Phius 2021 (or newer) Verification Report which demonstrates project compliance with Phius 2021 (or newer) performance requirements. b. A statement from the CPHC that the verification report results accurately reflect the plans submitted. c. Evidence of project registration from Phius. OR a. A Design Certification Letter from Phius. 2. Prior to the issuance of a certificate of occupancy, the following items must be provided to the building official: a. Design Certification Letter from Phius. b. An updated Verification Report by the CPHC which reflects “as-built” conditions and test results that demonstrate project compliance with Phius (blower door and ventilation results). c. A statement from the CPHC that the envelope meets the Phius hygrothermal requirements found in Appendix B of the Phius 2021 Certification guidebook d. A statement from the Phius Certified Verifier or Rater that the project test results and other Phius verification requirements are met. e. A copy of the Phius workbook listing all testing results and as-built conditions. OR a. A Project Certificate demonstrating final certification awarded by Phius. AND f. A statement from the Phius Verifier or Rater of compliance with R404.4: EV ready, and Appendix RB: Solar Ready Provisions. R405.3 Passive House International (PHI) Documentation. 1. If using PHI Passive House software, prior to the issuance of a building permit, the following items must be provided to the Building Official: a. A PHPP compliance report which demonstrates project compliance with current PHI performance requirements; b. A statement from the Certified Passive House Consultant/Designer (CPHC/D) that the PHPP results and compliance report accurately reflect the plans submitted; c. Evidence of project registration from a Certified Passive House Certifier. OR a. A Design Certification Letter from a Certified Passive House Certifier. 2. Prior to the issuance of a certificate of occupancy, the following item(s) must be provided to the building official: a. A Design Certification Letter from a Certified Passive House Certifier.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 10 | P a g e b. An updated PHPP compliance report which reflects “as-built” conditions and test results (blower door and ventilation results) that demonstrate project compliance with PHI performance requirements; c. A statement from the CPHD that the project test results meet the model performance requirements, all the mandatory limits and any other mandatory requirements. d. A copy of the Passive House Verifier’s or Rater’s test results; OR a. A Final Certification Letter from a Certified Passive House Certifier AND e. A statement from the Passive House Verifier or Rater of compliance with R404.4: EV ready, and Appendix RB: Solar Ready Provisions. R406.2 Revise TABLE R406.2 as follows: TABLE R406.2 REQUIREMENTS FOR ENERGY RATING INDEX SECTIONa TITLE R401.2.5 Additional efficiency packages R403.6.1 Heat or Energy Recovery Ventilation Electrical Power and Lighting Systems R404.1 Lighting equipment R404.2 Interior lighting controls R404.4 Wiring for Electric Vehicle Charging Spaces R406.3 Building thermal envelope a. Reference to a code section includes all of the relevant subsections except as indicated in the table. R406.3 Reserve this section: R406.3 Building thermal envelope. Reserved. R406.4 Replace Section R406.4 with the following: R406.4 Energy Rating Index. The Energy Rating Index (ERI) shall be the RESNET certified HERS index determined in accordance with RESNET/ICC 301. Energy used to recharge or refuel a vehicle used for transportation on roads that are not on the building site shall not be included in the ERI reference design or the rated design. R406.5 Replace Section R406.5 and Table R406.5 with the following: R406.5 ERI-based compliance. Compliance based on an ERI analysis requires that the rated proposed design and confirmed built dwelling be shown to have an HERS index rating less than or equal to the appropriate value indicated in Table R406.5 when compared to the HERS index reference design for each dwelling unit prior to credit for onsite renewable electric generation.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 11 | P a g e TABLE R406.5 MAXIMUM ENERGY RATING INDEX Clean Energy Application Maximum HERS Index scorea, b New construction until June 30, 2024 New construction permits after July 1, 2024 Major alterations, additions, or Change of usec Mixed-Fuel Building 52 42 52 Solar Electric Generation 55 42 55 All-Electric Building 55 45 55 Solar Electric & All- Electric Building 58 45 58 a Maximum HERS rating prior to onsite renewable electric generation in accordance with Section R406.5 b The building shall meet the mandatory requirements of Section R406.2, and the building thermal envelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or Table R402.1.4 of the 2015 International Energy Conservation Code. c Alterations, Additions or Change of use covered by Section R502.1.1 or R503.1.5 are subject to this maximum HERS rating. R406.5.1 Add Subsection R406.5.1, as follows: R406.5.1 Trade-off for Clean energy systems. New construction following Section R406 or existing buildings and additions following IECC chapter 5[RE] may use clean energy trade-offs to increase the maximum allowable HERS rating for each unit separately served by any combination of the following: 1. Solar Electric Generation: Solar photovoltaic array rated at 4kW or higher shall offset 3 HERS points for Level 3 alterations, Change of use to Residential R-use categories or for fully attached additions. 2. All-Electric Buildings shall offset 3 HERS points for each dwelling unit in new construction, Level 3 alterations, change of use to Residential R-use categories and fully attached additions. R406.6 Revise Section R406.6 by replacing the reference to Section R406.6 in the first sentence with reference to Section R406.5. R407 Reserve this Section: SECTION R407 Reserved. R408.2.1 Revise the first sentence of Subsection R408.2.1 by replacing 95 percent with 90 percent to read as follows: R408.2.1 Enhanced envelope performance option. The total building thermal envelope UA, the sum of U-factor times assembly area, shall be less than or equal to 90 percent of the total UA resulting from multiplying the U-factors in Table R402.1.2 by the same assembly area as in the proposed building. The UA calculation shall be performed in accordance with Section R402.1.5. The area-

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 12 | P a g e weighted average SHGC of all glazed fenestration shall be less than or equal to 95 percent of the maximum glazed fenestration SHGC in Table R402.1.2. R408.2.2 Delete option 1. of Subsection R408.2.2 and renumber option 2. As option 1., and option 3 as option 2. R408.2.2 More efficient HVAC equipment performance option. Heating and cooling equipment shall meet one of the following efficiencies: 1. Greater than or equal to 10 HSPF/16 SEER air source heat pump. 2. Greater than or equal to 3.5 COP ground source heat pump. For multiple cooling systems, all systems shall meet or exceed the minimum efficiency requirements in this section and shall be sized to serve 100 percent of the cooling design load. For multiple heating systems, all systems shall meet or exceed the minimum efficiency requirements in this section and shall be sized to serve 100 percent of the heating design load. R408.2.3 Delete option 1. of Subsection R408.2.3 and renumber option 2. As option 1., and option 3 as option 2. R408.2.3 Reduced energy use in service water-heating option. The hot water system shall meet one of the following efficiencies: 1. Greater than or equal to 2.0 UEF electric service water-heating system. 2. Greater than or equal to 0.4 solar fraction solar water-heating system. CHAPTER 5 [RE] EXISTING BUILDINGS SECTION R502 ADDITIONS. R502.1 Revise Subsection R502.2 by replacing the third and fourth sentence as follows: An addition shall be deemed to comply with this code where the addition alone complies, where the existing building and addition comply with this code as a single building, or where the building with the addition achieves a certified HERS rating in accordance with Table R406.5. Additions shall be in accordance with Section R502.1.1, R502.2 or R502.3. R502.1.1 Add Subsection R502.1.1 as follows: R502.1.1 Large additions. Additions to a dwelling unit exceeding 1,000 sq ft or exceeding 100% of the existing conditioned floor area, shall require the dwelling unit to comply with the maximum HERS ratings for alterations, additions or change of use shown in TABLE R406.5.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 13 | P a g e R502.2 Delete the Exceptions in Subsection R502.2. R502.3.1 Replace the Exception in Subsection R502.3.1 as follows: Exception: New envelope assemblies in additions of less than 1,000 sq ft are exempt from the requirements of Section R402.4.1.2. R503.1.5 Add new subsection as follows: R503.1.5 Level 3 Alterations, or Change of Use. Alterations that meet the IEBC definition for Level 3 Alteration or the IRC definition for Extensive Alteration, exceeding 1,000 sq ft or exceeding 100% of the existing conditioned floor area, shall require the dwelling unit to comply with the maximum HERS ratings for alterations, additions or change of use shown in Table R406.5. R505.1 Delete the Exception in Section R505.1.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 14 | P a g e Appendix RB revise the Appendix RB title as follows: Appendix RB: Solar-ready Provisions – Detached One- and Two-family Dwellings, Low-rise Residential buildings and Townhouses (Adopted as amended) RB101.1 Replace Section RB101.1 as follows: RB101.1 General. These provisions shall be applicable for new construction, except additions under 1,000 sq ft. Exception: Buildings and dwelling units complying with Appendix RC Sections RC102 or RC105 RB103.1 Replace Section RB103.1 as follows: RB103.1 General. New R-use buildings including, but not limited to, detached one- and two- family dwellings, and townhouses with not less than 600 square feet (55.74 m2) of roof area oriented between 110 degrees and 270 degrees of true north shall comply with Sections RB103.2 through RB103.8. Exceptions: 1. New residential buildings with a permanently installed on-site renewable energy system. 2. A building with a solar-ready zone that is shaded for more than 70 percent of daylight hours annually. RB103.3 Replace International Fire Code with Massachusetts Fire Code in Section RB103.3:

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 15 | P a g e Appendix RC revise the Appendix RC title and notes as follows: APPENDIX RC MASSACHUSETTS MUNICIPAL OPT-IN SPECIALIZED STRETCH CODE 2023 RESIDENTIAL LOW-RISE BUILDING PROVISIONS The provisions contained in this appendix together with referenced sections from the Stretch energy code constitute the Specialized opt-in code for residential low-rise buildings, and may be adopted by a city or town together with the Commercial Specialized code Appendix CC as their stretch energy code. When adopted by the local municipality, the provisions in this appendix are mandatory in combination with the IECC2021 with Massachusetts Stretch code amendments. User Note: About this appendix: This appendix provides requirements for residential buildings. Where adopted by ordinance as a requirement, Section RC101 language is intended to replace Section R401.2. SECTION RC101 COMPLIANCE RC101 Revise Section RC101 as follows: RC101.1 Compliance. Existing residential buildings shall comply with Chapter 5 of the stretch energy code. New residential buildings shall be Net Zero Buildings and comply with Section R404.4 (EV wiring) and either Section R405 (Passive House) or Section R406 (HERS) in accordance with RC101.2, as well as one of the following Specialized code pathways: 1. Section RC102 Zero Energy pathway 2. Section RC103 All-Electric pathway 3. Sections RC104 and RC105 Mixed-Fuel pathway. RC101.2 Application. New dwelling units over 4,000 square feet in conditioned floor area shall comply with either RC101.1 option 1. Zero Energy pathway or option 2. All-Electric pathway, and follow either Section RC102 or Section RC103.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 16 | P a g e R-use buildings with total conditioned floor area greater than 12,000 square feet shall comply with the provisions of Section R405 Passive House Building Certification Option, and any of the pathways in Section RC101.1. RC101.3 Definitions. NET ZERO BUILDING. A building which is consistent with achievement of MA 2050 net zero emissions, through a combination of highly energy efficient design together with being either a Zero Energy Building, or an All-Electric Building, or where fossil fuels are utilized, a building fully pre-wired for future electrification and that generates solar power on-site from the available Potential Solar Zone Area. ZERO ENERGY BUILDING. A building which through a combination of highly energy efficiency design and onsite renewable energy generation is designed to result in net zero energy consumption over the course of a year as measured in MMBtus or KWheq, on a site energy basis, excluding energy use for charging vehicles. RC102 Replace Section RC102 and Table RC102.2 as follows: SECTION RC102 ZERO ENERGY PATHWAY RC102.1 General. New zero energy buildings shall comply with Section RC102.2 and demonstrate a certified HERS rating of 0 or less and comply with Section R406, or complete Design Certification to the Phius ZERO standard and comply with Section R405. RC102.2 Energy Rating Index Zero Energy Score. Compliance with this section requires that the final HERS rated design be shown to have a score less than or equal to the values in Table RC102.2 when compared to the HERS reference design determined in accordance with RESNET/ICC 301 for both of the following: 1. HERS value not including on-site power production (OPP) calculated in accordance with RESNET/ICC 301. 2. HERS value including on-site power production calculated in accordance with RESNET/ICC 301 with the OPP in Equation 4.1.2 of RESNET/ICC 301. TABLE RC102.2 MAXIMUM HERS RATING INDEXa FUEL USAGE HERS RATING INDEX NOT INCLUDING OPP HERS RATING INDEX INCLUDING OPP All Electric 45 0 Mixed-Fuel 42 0 a. The building shall meet the requirements of Table R406.2, and the building thermal envelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or R402.1.3.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 17 | P a g e RC103 Add Section RC103 and Table RC103.2 as follows: SECTION RC103 ALL ELECTRIC PATHWAY RC103.1 General. New all electric buildings shall comply with Section R401.2.5 and either Section RC103.2 to demonstrate a certified final HERS rating of 45 or less, or Section R405 and be pre-certified to the PHI or Phius CORE standard. All new buildings shall comply with Appendix RB solar ready provisions and Section R404.4 Wiring for Electric Vehicle Charging Spaces RC103.2 All Electric HERS Rating Index score. Compliance with this section requires that the rated design be shown to have a certified HERS Index score less than or equal to the values in Table RC103.2 when compared to the HERS reference design determined in accordance with RESNET/ICC 301 and the following: 1. HERS value not including on-site power production (OPP) calculated in accordance with RESNET/ICC 301. TABLE RC103.2 MAXIMUM HERS RATING INDEXa FUEL USAGE HERS RATING INDEX NOT INCLUDING OPP All Electric 45 a. The building shall meet the requirements of Table R406.2, and the building thermal envelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or R402.1.3. RC104 Add Section RC104 and Table RC104.2 as follows: SECTION RC104 MIXED-FUEL PATHWAY RC104.1 General. This section establishes requirements for new residential mixed-fuel buildings with any space heating systems, water heating systems or appliances capable of using fossil fuels such as natural gas, heating oil or propane fuel. All buildings shall comply with either: 1. HERS certification: Sections RC104.2 through RC104.5 and RC105 2. Passive House pre-certification: Section R405 and Section RC104.3 RC104.1.1 Biomass heating. New residential buildings using clean biomass heating systems may comply with this section. Biomass heating that does not meet the performance standards of clean biomass heating systems shall not be permitted as a primary heating system. RC104.2 HERS Rating Index score. Compliance with this section requires that the rated

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 18 | P a g e design be shown to have a HERS Index score less than or equal to the values in Table RC103.2 when compared to the HERS reference design determined in accordance with RESNET/ICC 301 for both of the following: 1. HERS value not including on-site power production (OPP) calculated in accordance with RESNET/ICC 301. TABLE RC104.2 MAXIMUM HERS RATING INDEXa FUEL USAGE HERS RATING INDEX NOT INCLUDING OPP Mixed-Fuel building 42 a. The building shall meet the requirements of Table R406.2, and the building thermal envelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or R402.1.3. RC104.3 Electric Readiness. Any installed gas, fuel oil or propane furnaces, boilers, water heaters, dryers, or cooking equipment shall comply with the requirements of Sections RC104.3.1 through RC104.3.4. Capacity for the future electric circuits required in this section shall be included in the load calculations of the original installation of electric service to the building and each dwelling unit. RC104.3.1 Space Heating. The building and each dwelling unit shall be provided with a designated exterior location(s) in accordance with the following: 1. Natural drainage for condensate from cooling equipment operation or a condensate drain located within 3 feet (914 mm), and 2. A dedicated branch circuit in compliance with IRC Section E3702.11 based on heat pump space heating equipment sized in accordance with R403.7 and terminating within 3 feet (914 mm) of the location with no obstructions. Both ends of the branch circuit shall be labeled “For Future Heat Pump Space Heater.” Exception: Where an electrical circuit in compliance with IRC Section E3702.11 exists for space cooling equipment based on heat pump space heating equipment sized in accordance with R403.7. RC104.3.2 Household Ranges and Cooking Appliances. An individual branch circuit outlet with a minimum rating of 250-volts, 40-amperes shall be installed within three feet of each gas or propane range or permanently installed cooking appliance. RC104.3.3 Household Clothes Dryers and Water Heaters. An individual branch circuit outlet with a minimum rating of 250-volts, 30-amperes shall be installed within three feet of each gas or propane household clothes dryer and water heater.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 19 | P a g e RC104.3.4 Water Heating Space. Any permanently installed domestic hot water heating equipment shall be installed in an indoor space: A) with a minimum volume of 700 cubic feet (20,000 L) or the equivalent of one 16-inch (406 mm) by 24-inch (610 mm) grill to a heated space and one 8-inch (203 mm) duct of no more than 10 feet (3048 mm) in length for cool exhaust air. B) that is at least 3 feet (914 mm) by 3 feet (914 mm) by 7 feet (2134 mm) high surrounding or within 3 feet (914 mm) of the installed water heater. RC104.4 On-site Renewable Energy New buildings shall comply with either RC104.4.1 or RC104.4.2. Buildings following HERS certification shall comply with the requirements of RC105 solar-roof zone. Buildings following the Passive House pre-certification shall comply with Appendix RB solar ready provisions. RC104.4.1 One- and two- family dwellings and townhouses. One- and two- family dwellings and townhouses shall install an on-site renewable energy system with a nameplate DC power rating measured under standard test conditions, of not less than 4kW per dwelling unit. Exception: 1. A building where the potential solar zone area is less than 300 square feet. RC104.4.2 Other Group R Occupancies. Buildings in Group R-2, R-3 and R-4 shall install an on-site renewable energy system with a rated capacity of not less than 0.75 W/ft2 multiplied by the gross conditioned floor area. Exceptions: 1. A building with a permanently installed domestic solar water heating system with a minimum solar savings fraction of 0.5. 2. A building where the potential solar zone area is less than 300 square feet. RC104.5 Electric Vehicle Readiness. All buildings shall comply with Section R404.4 Wiring for Electric Vehicle Charging Spaces. RC105 Add Section RC105 as follows: SECTION RC105 SOLAR-ROOF ZONE RC105.1 General. New detached one- and two-family dwellings, and townhouses with not less than 600 square feet (55.74 m2) of roof area oriented between 110 degrees and 270 degrees of true north shall comply with Sections RC105.2 through RC105.10. Exceptions: 1. A building where all areas of the roof that would otherwise meet the requirements of Section RC105 are in full or partial shade for more than 70 percent of daylight hours annually.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 20 | P a g e RC105.2 Construction document requirements for solar- zone. Construction documents shall indicate the solar zone. RC105.3 Solar zone area. The total solar zone area shall be not less than 300 square feet (27.87 m2) exclusive of mandatory access or setback areas as required by the MA Fire Code. New townhouses three stories or less in height above grade plane and with a total floor area less than or equal to 2,000 square feet (185.8 m2) per dwelling unit shall have a solar zone area of not less than 150 square feet (13.94 m2). The solar zone shall be composed of areas not less than 5 feet (1524 mm) in width and not less than 80 square feet (7.44 m2) exclusive of access or setback areas as required by the MA Fire Code. RC105.4 Obstructions. Solar zones shall be free from obstructions, including but not limited to vents, chimneys, and roof-mounted equipment. RC105.5 Shading. The solar zone shall be set back from any existing or new permanently affixed object on the building or site that is located south, east or west of the solar zone a distance not less than two times the object’s height above the nearest point on the roof surface. Such objects include, but are not limited to, taller portions of the building itself, parapets, chimneys, antennas, signage, rooftop equipment, trees and roof plantings. RC105.6 Capped roof penetration sleeve. A capped roof penetration sleeve shall be provided adjacent to a solar zone located on a roof slope of not greater than 1 unit vertical in 12 units horizontal (8-percent slope). The capped roof penetration sleeve shall be sized to accommodate photovoltaic system conduit and shall have an inside diameter of not less than 11/4 inches (32 mm). RC105.7 Roof load documentation. The structural design loads for roof dead load and roof live load shall be clearly indicated on the construction documents. RC105.8 Interconnection pathway. Construction documents shall indicate pathways for routing of conduit or plumbing from the solar-ready zone to the electrical service panel or service hot water system. RC105.9 Electrical service reserved space. The main electrical service panel shall have space to allow installation of a dual pole circuit breaker for solar electric installation. RC105.10 Construction documentation certificate. A permanent certificate, indicating the solar PV system size in AC and DC KW and or solar thermal size in KW equivalent and other requirements of this section, shall be posted near the electrical distribution panel, water heater or other conspicuous location by the builder or registered design professional.

225 CMR 22: MASSACHUSETTS RESIDENTIAL STRETCH ENERGY CODE AND MUNICIPAL OPT-IN SPECIALIZED CODE 2023 21 | P a g e CHAPTER 6 [RE] REFERENCED STANDARDS REFERENCED STANDARDS Add the following Referenced Standards: AHRI Air-Conditioning, Heating & Refrigeration Institute 2311 Wilson Blvd., Suite 400, Arlington, VA 22201 1060-2018. Performance Rating of Air-To-Air Exchangers for Energy Recovery Ventilation Equipment. CSA CSA Group 8501 East Pleasant Valley Road, Cleveland, OH 44131 CAN/CSA-C439-18. Laboratory methods of test for rating the performance of heat/energy-recovery ventilators. REGULATORY AUTHORITY: M.G.L. Ch. 25A, Sec. 6; St. 2021, Ch. 8.