Code of Massachusetts Regulations
225 CMR - DEPARTMENT OF ENERGY RESOURCES
Title 225 CMR 22.00 - Massachusetts Stretch Code and Specialized Code 213 For Low-rise Residential
Chapter 5 - [RE] EXISTING BUILDINGS
Section RC104 - MIXED-FUEL PATHWAY

Universal Citation: 225 CMR 22.00 MA Code of Regs RC104

Current through Register 1531, September 27, 2024

RC104 dd Section RC104 and Table RC104.2 as follows:

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. Passivehouse 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 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

aThe 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.

C104.3 Electric Readiness. Any installed gas, fuel oil or propane furnaces, boilers, water heaters, dryers, or cooking equipment shall comply with the requirements of Sections RC 104.3.1 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 three 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 three 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.

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 Passivehouse 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 no less than 4kW per dwelling unit.

Exception: 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.

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