Stretch Energy Code
Frequently Asked Questions
What is the stretch code?
The ‘Stretch code’ is a more energy efficient alternative to the base code. Buildings constructed to the Stretch Code use significantly less energy than buildings built to other current and previous building codes. In Massachusetts, over 90.8% of the population live in a city or town that has adopted the stretch code.
The Stretch Code was established in 2009 as part of implementing the Green Communities Act of 2008, which allows for municipalities to adopt an above-code energy option to comply with the Green Communities Program (criterion #5). The Stretch Code, which emphasizes energy performance, as opposed to prescriptive requirements, is designed to result in cost-effective construction that is more energy efficient than a home built to the "base" energy code.
Does Stretch Code Eliminate fossil fuels from our community?
NO. Fossil fuels are still allowed in the State of Massachusetts. The state of MA is moving towards electrification, with fossil fuels eliminated from residential construction no later than 2030 and perhaps sooner.
How many Towns have adopted and rescinded the Stretch Energy Code?
There are currently 301 MA municipalities enforcing a code above and beyond the base code. Presently 262 stretch AND 39 specialized code communities. In theory, all 301 of these towns are “stretch” code towns, covering ~92% of the population. 50 still remain base code. Source; https://www.mass.gov/doc/building-energy-code-adoption-by-municipality/download
Has Nantucket benefitted from the Stretch Code?
Yes. Besides establishing a clear compliance path for incorporating energy-efficiency and minimizing lifecycle costs in new construction, as well as very large additions and renovations, the Stretch Code has also allowed the Town of Nantucket to achieve “Green Communities” designation in 2020, and by doing so, has received $477,488 for energy efficiency improvements in municipal buildings to date.
Does Nantucket plan to pursue the adoption of the “specialized energy code”?
There is no current discussion by the Town of Nantucket to adopt the more-aggressive “Municipal Specialized Code.” The Specialized Code is not required for Nantucket to remain a Green Community or to continue receiving access to significant grant funding for facility upgrades.
What is the consequence of rescinding Stretch Code Adoption?
Nantucket would revert to enforcing the Base Code (IECC 2021). Nantucket would lose its Green Communities designation.
How do the base and Stretch codes differ?
The base energy code is currently based on amendments to the IECC 2018 national model code but will update to the IECC 2021 model code as part of a larger update to the building code as it moves from the 9th edition to the 10th edition. The base energy code in both the 9th and 10th editions provides two options residential builders may use to meet energy efficiency requirements:
Prescriptive Method, installing elements with specific energy efficiency levels (e.g., windows, or wall & roof insulation, furnace, etc.), or
Performance-based Method, building to ensure the home performs to a specific level of efficiency, typically measured through a HERS (Home Energy Rating System) or Passive House analysis, including both of the design plans and the actual built home once construction is completed. The builder can decide how to design the house to reach the performance target.
The Stretch code requires that builders use the performance-based method. Measuring the home in this way brings in a 3rd party energy expert who verifies it is designed and built to perform as expected, which is an important protection for the homeowner and for any future buyer. Some builders in non-Stretch code communities voluntarily choose to use the performance-based method required by the Stretch code because it can often provide greater flexibility.
What is the anticipated cost of building under the Stretch energy code?
Using the HERS Rating process allows the builder to value engineer the building, and often can SAVE money over the prescriptive Base Code. In addition, buildings designed and constructed in accordance to Stretch code standards, low-rise residential buildings built with all electric heating and cooling (via heat pumps) will typically cost less to build and operate than those built with fossil fuel heating. In addition, one reason for this is that heat pumps can be used for both heating and central air conditioning, whereas fossil fuel heated new homes typically require a separate air conditioning system.
DOER has commissioned studies to analyze the change in construction costs related to building to the Stretch code for several sizes and types of residences, and they generally indicate the construction and operating costs are lower under the Stretch code standards with fully electric heating and cooling via heat pumps. These case studies are available on DOER’s website here: https://www.mass.gov/doc/residential-Stretch-code-costs-and-benefits-case-studies/download
Is it true that only geothermal and ductless mini-splits will be usable under the Stretch Code?
No. With some adjustments to existing building practice, builders can continue to use dual fuel heat pumps supported by fossil fuel backup, or even high efficiency furnaces as primary heat sources. The value engineering built into the ERI/HERS process means you can offset a furnace with better windows, or increase exterior insulation and air sealing to offset the furnace and get to HERS 42 for a fossil fuel building. Highly efficient Energy Recovery Ventilators (ERVs) can pickup as many as 3 HERS points over ERVs from just a few years ago. The average HERS score in Massachusetts last year was 50, so HERS 45/42 is a 5-8% improvement in efficiency over the previous code cycle.
How does the Stretch code apply to historic buildings?
The rules for historic buildings are contained in IECC 2021 C501.5, and state that provisions relating to the repair, alteration, restoration and movement of structures, and change of occupancy are not mandatory for historic buildings provided a report has been submitted to the code official and signed by a registered design professional or representative of the State Historic Preservation Office of the historic preservation authority having jurisdiction, demonstrating that compliance with the provision would threaten, degrade, or destroy the historic form, fabric or function of the building.
What is a HERS rating?
HERS stands for ‘Home Energy Rating System,’ and is a national standard that uses information on the design of the energy systems in a home to calculate, via computer modeling, the average energy needs of that home and give it a rating score. The HERS Index was developed by the non-profit Residential Energy Services Network (RESNET) for the mortgage industry and is utilized by the Federal Internal Revenue Service (IRS) and the LEED for Homes program. On the HERS 2006 index scale smaller numbers are better, with 0 representing a net zero energy home, and 100 represents a home built to 2006 Standards (the 2004 IECC 2004 with 2005 amendments). A HERS rating of 52 means that the home uses about 48% less energy than the same size home built to the 2006 IECC code requirements.
How do I meet the residential Stretch code for new 1 and 2 family homes and townhouses?
For new residential homes including multi-family homes of 3 stories or less, builders can choose to either meet Home Energy Rating System (HERS) certification or Passive House certification. Starting January 1, 2023, the maximum allowed HERS Index Score for residential low-rise construction ranges from 52 (for residences heated with fossil fuels) to 58 (for all-electric residences with on-site solar PV). HERS Index scores will be reduced to 42 and 45 starting July 1, 2024.
The 2023 Stretch Code maintains differential HERS ratings among new construction heating with fossil fuels, all-electric, and/or including onsite solar; after a phase-in period until July 1, 2024, which will require HERS 45 for all-electric homes and HERS 42 for homes with any use of fossil fuels.
The 2023 Stretch Code also updates HERS requirements for extensive alterations, additions and change of use for existing homes. Builders wanting to achieve code compliance via Passive House certification will use the most recent Passive House Institute US (Phius) standards.
Existing buildings: Alterations, Additions and Changes of use:
The 2023 Stretch Code clarifies when alterations to existing homes trigger compliance with different requirements. The requirements are as follows:
- 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 (i.e., 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) or change of use exceeding 1,000 sf or exceeding 100% of the existing conditioned floor area, must meet the HERS requirements in Table 1 above. Level 1 and Level 2 alterations will continue to follow the Base Energy Code and can use Rescheck.
When is a HERS Rating required for an addition?
A HERS Rating is required where the total added conditioned floor area is greater than 1,000 square feet or the addition exceeds 100% of the existing dwelling unit conditioned floor area.
If multiple additions are made to the same dwelling unit and each is under 1,000 square feet, but the total adds up to more than 1,000 square feet, is a HERS Rating required?
Yes, the floor area of multiple additions should be treated cumulatively. When two or more additions add up to greater than 1,000 square feet, a HERS Rating is required.
Is the floor area trigger for when a HERS Rating is required for additions based on conditioned floor area?
Yes, only conditioned floor area is included when determining whether the addition requires a HERS Rating.
Can a HERS Rating be performed on an addition?
It depends. HERS Ratings may only be performed on dwelling units, so if the addition contains areas for living, sleeping, eating, cooking, and sanitation, a HERS Rating may be performed on the addition. If the addition is not a dwelling unit, the HERS Rating must be performed on the existing home plus the addition.
How does the push for more/all electrification work if one of the cables is down or one goes down in the future? Will increased electrification put more strain on the existing two cables?
Along with the push for electrification, there is the ongoing need and effort to reduce power consumption. One way to accomplish this is with increased energy efficiency in buildings.
Is there a current cable problem? Why did the second cable go down?
The cause is still unknown. Nantucket Current | One Of The Two Undersea Cables That Provide…