Thermal Energy Networks (TENs) for CT
About TEN4CT
PACE created TEN4CT in this summer to promote the development of community-led Thermal Energy Networks (TENs) in Connecticut. This was prompted by the establishment of a TEN grant and loan program by the CT General Assembly.
We have a sense of urgency when it comes to decarbonizing the heating and cooling of buildings, which accounts for about 35% of all greenhouse gas emissions in the U.S. Electrifying buildings one-by-one with air source (ASHP) or ground source heat pumps (GSHP) is slow and often inefficient, though they have an essential role where building density can not support a TEN. TENs can decarbonize whole neighborhoods, interconnecting buildings through underground pipes that circulate ambient-temperature water. Each building draws or returns heat to the shared loop depending on the season using its own water-source heat pump—significantly reducing electricity use and strain on grid infrastructure.
However, TENs require upfront capital, multi-party coordination, and a shared vision. Feasibility studies, funded by a state grant program, led by municipal or community-based entities, and supported by experienced engineering firms are the key to determining project viability, fostering stakeholder collaboration, and unlocking next-stage funding
TEN4CT:
- Convenes monthly to discuss how local TENs might be formed by CT communities.
- Gathers useful resources in a web-based repository.
- Invites a variety of people to talk about their experience with community-led TENs.
- Advocates for funding the CT TEN grant and loan program.
To get on the TEN4CT email list and receive invitations to monthly meetings, please email Peter Millman at peter.millman7@gmail.com. All are welcome; no experience or knowledge of TENS is required.
Meeting Recordings
What is a TEN (Thermal Energy Network)?
Thermal energy systems use the natural heat stored in the ground, water, or air to provide clean and efficient heating and cooling. Unlike fossil-fueled boilers or electric resistance heaters, thermal networks (also known as geothermal district systems or ambient loop systems) move heat, instead of generating it, reducing greenhouse gas emissions and lowering energy bills. By moving heat between buildings, efficiency is increased. At times some buildings (like a grocery store that needs to refrigerate its products) shed heat and this heat can be moved into the thermal loop and serve another building in that loop that needs heat.
These systems can serve entire neighborhoods, schools, affordable housing developments, campuses, and even towns — and are essential to achieving a clean energy future in Connecticut.
CT’s TEN Grant and Loan Program
The new TEN Grant and Loan Program, created in 2025 under Section 32 of SB 4 (p. 80), establishes a state-run initiative within the Department of Energy and Environmental Protection (DEEP) to advance community-scale geothermal and thermal networks. The program provides grants and loans to a wide range of eligible recipients—including municipalities, regional councils of government, tribes, utilities, nonprofits, academic institutions, private developers, and energy improvement districts—to support the development of thermal energy networks on the customer side of the meter.
Funding can be used for planning and feasibility studies, design and engineering services, infrastructure costs, and as non-federal cost share to leverage other grant or loan programs. Recipients must comply with prevailing wage requirements, and each funded project must submit annual progress reports for three years to PURA, the Office of Consumer Counsel, DEEP, and the legislature’s Energy and Technology Committee. By opening eligibility broadly and covering projects from conception through construction, the program is designed to accelerate deployment of utility-scale distribution networks that deliver non-combustion heating and cooling to buildings as part of the state’s decarbonization strategy.
A prime goal of TEN4CT is to have the 2026 CT General Assembly fund this essential program, so that DEEP can begin providing grants to successful applicants.
Why It Matters in Connecticut
Connecticut relies heavily on fossil fuels for heating — oil, propane, and natural gas. This dependency drives up emissions, energy costs, and economic insecurity.
- Thermal energy networks offer a reliable, local alternative.
- They support climate justice, reducing energy burdens in low-income communities.
- They create local jobs in drilling, construction, and building trades.
- They help towns meet decarbonization and resilience goals.
Thermal energy is already in use — now we must scale it up.
How to Fund Thermal Energy Networks
Thermal networks can be funded through a combination of:
- Projected revenue from building owners and occupants for thermal services.
- State clean energy financing (via CT Green Bank, DEEP grants, or ratepayer funds)
- Municipal bonds for energy infrastructure
- Public-private partnerships
- Anchor institution commitments (schools, hospitals, housing authorities)
- Utility involvement (thermal as regulated utility service)
We advocate for expanded state support and enabling legislation to unlock large-scale deployment./sho
Resources
The Basics
- A 2-minute video that explains geothermal networks or Thermal Energy Networks. From HEET, a Massachusetts group that has been one of the principal proponents of this approach to electrifying building heating and cooling.
- A 4-minute video tour of Eversource’s Framingham, MA network geothermal pilot project.
- A Volts podcast episode with Audrey Schulman and Zeyneb Magavi on how to replace natural gas with renewable heat.
Case Studies
- Eversource’s Framingham, MA network geothermal pilot project
- Union Station Area Thermal Energy Network, New Haven
- Science Hill Development, Yale University
- The ‘Heaven and Earth’ plan that will loop most of downtown Salem, MA into a thermal energy network
- Can Solar and Geothermal Energy Help a Church and Its Neighbors Wean Off Fossil Fuels?
- A video presentation by Rev Nathan Ives, who developed the ‘Heaven and Earth’ plan. (Start at 6:45 in the video)
- A video presentation by Chris Till, Facilities Project Manager for the Town of Manchester, concerning their new Net Zero Energy library that may serve as the anchor for a geothermal network. (Start at 28:30 in the video)
- Five Ownership Case Studies from the Building Decarbonization Coalition
Feasibility Study Grant Programs in Other States
- Massachusetts launched the Kickstart Program through HEET and MassCEC in 2022, allocating $450,000 for 14 community-led feasibility studies of geothermal networks. The Kickstart website shares detailed proposals and stakeholder engagement tools.
- Colorado established the Geothermal Energy Grant Program (GEGP) in 2022 to fund planning and construction of district-scale, ambient-temperature TENs. GEGP supports local governments, schools, tribes, and nonprofits, with active projects now in development. The state frames TENs as a cornerstone of decarbonization and grid resilience.
Learn More
- HEET (Home Energy Efficiency Team)
- From (BDC) Building Decarbonization Coalition