Specialized Energy Code

What is the Specialized Energy Code?

The Specialized Energy Code is an initiative by the Commonwealth of Massachusetts to encourage stronger building efficiency standards for new building construction (NOT renovations or additions). This code pushes development towards high-performance standards, incentivizing (but not requiring) all-electric heating and cooling systems to improve energy efficiency..

At Annual Town Meeting in 2025, the Westford Select Board sponsored Article 20, which called for the adoption of the Specialized Energy Code. The motion to adopt the new code failed by a vote of 165 to 137. Westford currently requires the Stretch Code, which was most recently updated in 2023.  Adopting the Stretch Code is a requirement for participation in the Green Communities program, which Westford joined in 2013.

What Does the Specialized Energy Code Require?

The Specialized Energy Code only applies to new buildings, not renovations or additions. The Code is found as an appendix to both the Residential Low-Rise Stretch Energy Code (225 CMR 22.00 - see Appendix RC) and the Commercial Stretch Energy Code (225 CMR 23.00 - see Appendix CC).

For New Residential Buildings

  • All-electric buildings: No requirements beyond the existing building code already in effect in Westford.
  • Mixed-fuel buildings: Buildings that include fossil fuels (for heating, cooking, hot water or clothes drying) are allowed, but they must:
    • Be pre-wired for future electrification of relevant appliances; and
    • Homes smaller than 4,000 sq. ft must include rooftop solar panels (with exceptions for shaded sites) or meet the energy efficient Passive House standard; 
    • Homes 4,000 sq. ft. or larger must fully offset fossil fuel use with on-site renewable energy (solar panels).

For New Commercial and Municipal Buildings (including schools)

  • Similar requirements as residential buildings: no additional code requirements for all-electric buildings, and pre-wiring and rooftop solar requirements for mixed-fuel buildings. Municipal buildings include new school buildings.

For Large Apartment or Condominium Buildings (12,000 square feet or larger)

How Will This Benefit Westford?

  • The Specialized Energy Code will significantly help Westford meet the goals outlined in its Climate Road Map by reducing carbon emissions from new buildings. This move aligns with the town’s ongoing efforts to combat climate change and promote sustainability.
  • The Specialized Energy Code is grid friendly, increasing energy efficiency and the use of renewable energy. The Passive House standard for multifamily can reduce heating demands by 90% and overall energy demand by 60%
  • Adopting the Specialized Energy Code is a critical step for Westford to qualify as a Climate Leader Community, an advanced version of the Green Communities program. As a Climate Leader, Westford would be eligible for additional state funding for sustainability projects, including building energy efficiency improvements, electric vehicles, and solar panel installations. In November 2024, the State of Massachusetts announced $60 million in new grant funding for Climate Leader Communities. Some additional work is needed to make Westford eligible for Climate Leader status.

Frequently Asked Questions

Where can I read more about the updated Stretch Code and Specialized Code?

The Stretch and Specialized codes are 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).

How is the Specialized Code different from the Stretch Code?

The Specialized Energy Code goes beyond the base and stretch energy codes by requiring homes to either be all-electric, or if built with fossil fuel appliances, to be wired for easy and inexpensive future electrification. It also mandates rooftop solar installations on new homes unless the home is smaller than 4,000 square feet of conditioned area and the site is shaded.

What building types does the Stretch Code and Specialized Code apply to?

The Stretch Code applies to both residential and commercial new construction, as well as certain renovations and additions. The Specialized Code applies only to residential and commercial new construction.

Can buildings still have gas cooktops, water heaters or other appliances along with all-electric heating and cooling under the Specialized Code? 

Yes, but this will make the building a “mixed-fuel” building, requiring pre-wiring for future electrification and on-site renewable energy offsets. 

Are emergency generators allowed?

Yes, fossil fuel powered emergency generators are allowed for all building sizes and types. 

Why is there a pre-wiring requirement?

The Specialized Code was developed to be consistent with the Commonwealth’s net-zero by 2050 goals. Wiring for electrification is easy and low cost at the time of construction but becomes expensive and time-consuming after construction. The pre-wiring requirement protects against high consumer costs for future retrofits, which will be necessary to meet the Commonwealth’s climate goals.

How much solar is required for residential buildings using fossil fuels?

One- and two- family dwellings and townhouses that use fossil fuels must install at least 4kW of solar per dwelling unit, except when the potential solar zone area (refer to code for definition) is less than 300 square feet. Other low-rise residential buildings that use fossil fuels must install on-site solar PV system with a rated capacity of not less than 0.75 W/ft of the gross conditioned living area, except when the Potential Solar Zone Area (refer to code for definition) is less than 300 square feet or when the building has a permanently installed domestic solar water heating system with a minimum solar savings fraction of 0.5.

My residence is surrounded by trees – do I have to cut down trees to meet the onsite solar requirements?

No. There are exceptions to the onsite solar requirements:

  • Roof area oriented between 110 degrees and 270 degrees of true north of new one-and two family homes and townhouses is under 600 square feet.
  • Roof area is in full or partial shade for more than 70 percent of daylight hours annually.

How much solar is required for commercial buildings using fossil fuels?

New buildings that fall under the commercial code and use fossil fuels must install on-site renewable energy with a rated capacity of at least 1.5 W/ft of the gross conditioned floor area of the three largest floors. Where the building site cannot meet the requirement in full with an on-site system, the building site shall install a partial system sized to at least 75% of the Potential Solar Zone Area (refer to code for definition).

Will the Specialized Code discourage the creation of affordable housing?

No, because financial incentives through MassSave and competitive incentives from the Department of Housing and Community Development make development of affordable housing attractive including incentives to meet the Specialized Code. All-electric buildings result in little, if any, additional construction costs. And third party power purchase agreements can provide solar energy with no upfront cost. 

Are there additional EV charging requirements in the Specialized Code?

No, there are no additional EV charging requirements beyond the Stretch Code requirements.

Additional Background


Benefits of the Specialized Energy Code


Lower Operating Costs
All-electric homes and buildings often have lower operating costs compared to those that use fossil fuels. This is because electric systems are generally more efficient, and the costs of renewable energy, like solar power, are continuing to decrease.

Healthier Living Environments
The Specialized Energy Code promotes healthier indoor air quality by reducing or eliminating on-site fossil fuel combustion, which can produce harmful pollutants. All-electric homes have no combustion appliances, leading to cleaner, safer air inside.

Climate Resilience
By promoting electrification and renewable energy, the Specialized Energy Code helps communities prepare for a future where fossil fuels may be more expensive or less available. This also contributes to the reduction of greenhouse gas emissions, helping Winchester meet its climate goals.

Increased Property Value
Homes built to higher energy efficiency standards typically have increased property values. Buyers are increasingly looking for homes that are energy-efficient, sustainable, and cost-effective to operate.

State and Federal Incentives
Buildings that comply with the Specialized Energy Code may qualify for various state and federal incentives, such as rebates, grants, and tax credits. These incentives can offset the initial costs of energy-efficient construction and renewable energy installations.

There are three levels of building energy codes in Massachusetts: 


  • The Base Code
  • The Stretch Code
  • The Specialized Code

The Base Code is the International Energy Conservation Code (IECC) with Massachusetts-specific amendments. 

In 2009, Massachusetts became the first state to adopt an above-code appendix to the “base” building energy code. The Stretch Code emphasizes energy performance and was designed to result in cost-effective construction that is more energy efficient than that built to the Base Code. The Stretch Code is typically updated every few years, with the most recent update taking effect in 2023. Adopting the Stretch Code is a requirement for participation in the Green Communities program.

The Specialized Code was developed in 2022, following direction from the Commonwealth’s Climate Act of 2021 to develop a municipal opt-in code that advanced net-zero building performance. The Specialized Code builds on the efficiency and clean energy standards in the updated Stretch Code and pushes new construction towards deep energy efficiency, reduced heating loads, consumer protection, and efficient electrification. Learn more about the development of the updated Stretch Code and the Specialized Code. 

The Specialized Code builds off the Stretch Code and only adds requirements to new construction. The Specialized Code is found as an appendix to both the Residential Low-Rise Stretch Energy Code (225 CMR 22.00) and the Commercial Stretch Energy Code (225 CMR 23.00). The Specialized Code can be summarized as follows:

  1. No additional requirements beyond the Stretch Code for additions, alterations, or renovations.
  2. No additional requirements beyond the Stretch Code for all-electric new construction, except for multifamily housing over 12,000 square feet.
    1. Provide pre-wiring for future appliance and HVAC electrification 
    2. Install a minimum amount of solar (with some exceptions for shading) 
    3. Homes over 4,000 square feet must install enough solar or other renewables to offset ALL of the home’s energy use
  3. Any new multifamily housing over 12,000 square feet will need to meet Passive House standards