Frequently Asked Questions about the Specialized Stretch Energy Code

Frequently Asked Questions about the Specialized Stretch Energy Code

The table below describes how the Specialized Stretch Energy Code impacts residential buildings.[1]

Building Type	Energy Source	Specialized Stretch Energy Code requirement
Less than 4000 sq ft	All electric	No new requirements
	Mixed Fuel	+ Solar PV (min 4kW)* + wiring for electrification
>= 4000 sq ft	All electric	No new requirements
	Mixed Fuel	+ Solar PV (to be net zero energy)* + wiring for electrification
Multi-family >12,000 sq ft	All electric	Passive House standards
	Mixed Fuel	Passive House standards + wiring for electrification
Home additions and alterations	Any	No new requirements

*Solar is required for new, mixed-fuel buildings when there is a solar roof zone >=300 sq ft AND at the right orientation (tree removal is not required).

 

FREQUENTLY ASKED QUESTIONS:

1. Why adopt the Specialized Stretch Energy Code?

• • It will unlock more grant funding to improve town buildings.

• • It requires pre-wiring for electrification, avoiding costly retrofits in the future.

• • It reduces operational expenses for new homeowners in Groton.

2. Does the Specialized Stretch Energy Code apply to existing structures?

• • No. Improvements to existing structures will continue to be regulated by the current Stretch energy code enforced in Groton.

3. Is it possible to install an oil boiler, propane cooktop or water heater in a newly constructed home under the Specialized Stretch energy code?

• • Yes. This is permitted under the Mixed Fuel pathways.

4. Can a fossil fuel back-up generator be installed in an all-electric home?

• • Yes.   Under the Specialized Stretch energy code, an all-electric home with a fossil fuel backup generator does not require the extra requirements for multi-fuel homes.

5. Has the Specialized Stretch energy code reduced housing production in those communities that have adopted it?

• • No. A recent study showed that communities that have adopted the Specialized Stretch energy code do not have lower rates of housing production than communities without the Specialized Stretch energy code.[2]

6. Does it cost more to build an all-electric home than a mixed-fuel home?

1. • No. Three studies conducted between 2022 and 2024 concluded that building an all-electric home in Massachusetts was within +/-1% the cost of building a mixed-fuel home.[3] Moreover, local HVAC installers agreed that the cost of installing a heat pump to heat and cool a new all-electric home is the same or less than the cost of installing fossil fuel furnace/boiler + air-conditioning systems (multi-fuel) in the same new home.How will the Specialized Stretch Energy Code impact the regional grid.

7. How will the Specialized Stretch Energy Code impact the regional grid 

• • The energy efficiency of new buildings constructed under the Specialized Stretch energy code is considered one of the many tools needed to reduce growing peak demand expected from electrification and data centers.[4] Higher peak demand drives higher ratepayer costs.

8. Can a heat pump heat a new home in New England?

• • Yes. Modern cold-climate heat pumps can provide heat when outside temperatures are even below -10F.[5] In addition, due to the high energy efficiency required of new buildings from Groton’s current Stretch Energy code, the energy required to heat and cool new homes is much lower than older homes. The poor energy efficiency of older existing homes makes it more difficult for heat pumps to supply all of the energy required to heat older, inefficient homes. The Specialized Stretch energy code only applies to NEW buildings.

9. How does electrification reduce greenhouse gas (GHG) emissions if some of our electricity is generated by burning fossil fuels at power plants?

• • A new all-electric home heated with heat pumps emits ~50% less greenhouse gas emissions than a home heated with fossil fuels TODAY. As the electric grid reduces fossil fuel generation sources over time, GHG from all-electric homes will decrease even more.

10. How does a well-insulated, well air-sealed (i.e. energy efficient) building “breathe?”

• • All new homes require mechanical ventilation systems[6]

[1] To learn about Specialized Stretch energy code requirements for commercial buildings visit: Learn about the Specialized Stretch Code – Sustainable Groton

[2] https://phmass.org/2025/12/30/codes-and-housing-supply/

[3] https://rmi.org/insight/the-economics-of-electrifying-buildings-residential-new-construction/;

https://hbrama.com/wp-content/uploads/2023/05/Public-Policy-for-Net-Zero-Homes-and-Affordability-Final-6-14-23.pdf

BEplus_MA_is_Going_Net_Zero.04.30.24.pdf

[4] https://www.mass.gov/doc/doer-peak-potential-report-and-policy-recommendations/download

[5] https://www.consumerreports.org/heat-pumps/can-heat-pumps-actually-work-in-cold-climates-a4929629430/; https://rmi.org/heat-pumps-a-practical-solution-for-cold-climates

[6] 225 CMR 22