The cheapest way to heat a building might be the ground under it. Networked geothermal, the practice of linking many buildings to a shared underground loop instead of a furnace per address, is moving from science project to construction project in 2026. Utilities are the ones picking up the shovel, and that changes the math.
The clearest signal came out of Massachusetts. The U.S. Department of Energy awarded Eversource, the City of Framingham, and the nonprofit HEET a $7.8 million grant to build a second geothermal loop and tie it into the pilot network already running there. Eversource wants the new loop installed in 2026. A regulated gas utility digging bore fields instead of laying pipe is the part worth noticing.
Why thermal energy networks pencil out
The engineering isn’t new. Ground-source heat pumps post coefficients of performance between 3.0 and 4.5, meaning three to four and a half units of heat moved per unit of electricity, and they can cut heating and cooling energy use by up to roughly 65% against conventional systems. What’s new is the network. Connect a loop across a street or a campus and the buildings start trading heat with each other. A data closet dumping heat helps warm the apartments next door.
That sharing is what trims peak demand on the electric grid, which matters when the same grid is straining under data center load and new transmission can’t get built fast enough. Heat that stays local doesn’t need a new power line.
Where the geothermal buildout is happening
Campuses are early movers because they own both the land and the buildings. Central Washington University’s open-loop ground-source plant is built to heat and cool about half a million square feet across its campus. Institutional owners with long horizons and tight carbon targets pencil these systems out more easily than a developer flipping a building in five years.
Policy is the swing factor, and it cuts both ways. Massachusetts regulators handed networked-geothermal advocates a setback this cycle, even as a proposed geothermal service rate moves through gas planning that would let utilities recover the cost of thermal networks the way they recover pipe. The federal tax credit helps too, starting at a 6% base before it steps down after 2032. The economics aren’t universal yet. For owners chasing LEED v5 and hard carbon targets, though, the case is getting easier to make.
Watch the utility rate cases, not the ribbon cuttings. Whether networked geothermal scales past pilots depends less on the drilling and more on whether regulators let utilities treat underground loops as the infrastructure they are.