January 30, 2026

CT Construction Digest Friday January 30, 2026

Update of Hartford’s underground loop heating system on hold

John Moritz

A contentious plan to heat state office buildings in downtown Hartford with a new generation of gas-powered boilers is on hold due to potential interference from the planned reconstruction of Interstate 84, officials confirmed this week.

In an interview Wednesday, Department of Administrative Services Commissioner Michelle Gilman said her agency decided late last year to pause a planned renovation of the Capitol Area System — a network of 15 buildings connected by underground heating and cooling pipes known as the “loop” — following discussions with other state officials about need to utilize space around the loop for highway construction.

By agreeing to pause the project, Gilman said the state would avoid wasting money on new equipment that might later need to be removed to accommodate the highway. In addition, she said the pause will give officials more time to consider more climate-friendly alternatives to new gas investments that have been pushed by some advocates.

“We are going to need some time to understand what the options look like,” Gilman said. “We have not engaged in those next steps yet.”

In the meantime, Gilman said the state will focus on maintaining and making repairs to the existing system, which opened in 1988.

The loop is powered by the CAS thermal plant on Capitol Avenue, which utilizes natural gas boilers to provide heat and hot water for hundreds of state offices, as well as some private buildings such as the Bushnell Performing Arts Center. (The state Capitol building relies on a separate system to heat and cool the 146-year-old building.)

Last year, the state Department of Administrative Services — which oversees the CAS and many individual buildings along the loop — announced plans to replace the system’s existing boilers with a combination of heat pumps and newer natural gas boilers to provide hot water, air and steam to the buildings.

The so-called “hybrid” approach angered local community members and environmental advocates, who pushed the state to install an all-electric or geothermal heating and cooling system that would send fewer emissions into the surrounding air. Similar systems are under development at other state offices and at New Haven’s Union Station.

Alycia Jenkins, an organizer with the Sierra Club who helped lead efforts to oppose the state’s plans, said that while she was pleased with the decision to pause the project she wanted officials to commit to considering alternatives that don’t use fossil fuels.

“I just hope that we’re able to get the state to pivot,” Jenkins said. “They should build it once and build it right. It’s worth it to the people of Hartford, and it can be a beacon for the rest of the state.”

A study completed for the state in 2023 found that the use of electric heat pumps or a geothermal system would reduce carbon emissions by up to 80% compared to the hybrid model originally selected by DAS. However, the same report also found that those alternatives could potentially double the lifetime cost of building and operating a new gas system.

On Tuesday, Gilman sent an email to Jenkins and other members of the Sierra Club saying her agency did not plan on conducting any new studies in the next year, as officials seek more details about timeline of the I-84 project.

Gilman later told the Connecticut Mirror that the highway project may necessitate relocating the CAS plant to a new location. In addition, she said DAS would evaluate the possibility of closing the loop altogether and replacing it with several smaller HVAC systems — though she cautioned that such an option was unlikely given the costs.

Gilman declined to provide a timeline for when DAS would reach a final decision on the future of the CAS, saying that it would depend largely on the scope of the Department of Transportation’s work on the interstate. She also said the agency remained open to utilizing a geothermal system, if conditions permit one.

“We love that option for geothermal on projects where they can work and where various properties are sized to be able to include geothermal and where it makes fiscal sense to do so,” Gilman said.

Jenkins said her group plans to contact state lawmakers during the upcoming legislative session in order to discuss the future of CAS. On Wednesday, she and another organizer, Tenaya Taylor, read a poem at a rally held on the steps on the state Capitol to call for legislation holding large polluters financially accountable for the damages caused by fossil fuel emissions.

“We have the wind at our back,” Jenkins said. “I have confidence that we’re in it for the long-haul, we’re in it for the good fight.”