New York Construction Report staff writer
New York City, New York state and the Metropolitan Transportation Authority (MTA) are studying a thermal energy network that could cool some of the city’s hottest subway platforms while capturing excess heat for use in nearby municipal buildings.
Mayor Mamdani, Gov. Kathy Hochul and the MTA announced the partnership Friday, saying the proposed system would be the first thermal energy network installed in a U.S. transit system.
The feasibility study will focus on the Brooklyn Bridge-City Hall 4/5/6 and Chambers Street J/Z station complex. The initiative comes days after Hochul and the MTA announced plans for a major renewal of the Chambers Street station, one of the oldest in the subway system.
Brooklyn Bridge-City Hall is among the hottest stations in the system, with average summer temperatures reaching 96 F in 2025. The MTA has prioritized getting riders onto air-conditioned trains more quickly, but officials say the study could identify longer-term ways to reduce platform temperatures and heat-related service problems.
“There are few feelings worse than escaping the extreme summer heat only to find yourself on a subway platform that is even hotter,” Mamdani said. “We now have an opportunity to do more than rebuild Chambers Street top to bottom. We can make our subway platforms cooler and more comfortable while putting wasted heat to work during the winter.”
The proposed system would use radiant cooling to absorb heat from the Brooklyn Bridge-City Hall platforms, and potentially Chambers Street as well. The heat would be transferred through pipes to geothermal boreholes beneath an abandoned centre platform at Chambers Street.
Heat could then be stored underground and redirected during colder months to heat nearby municipal buildings.
The abandoned centre platform at Chambers Street makes the station particularly suited to the study because it could allow testing of the technology without disrupting passenger areas.
“Working with Mayor Mamdani and the MTA, we are harnessing cutting-edge climate technology for a truly cool purpose: making our subway stations tolerable during the summer and heating critical city buildings during the winter,” Hochul said.
The Chambers Street station renewal project will rebuild structures, replace tiles, upgrade stairways and restore the station. The work is being funded through congestion pricing and provides an opportunity to examine thermal energy infrastructure as part of the broader station improvements.
Thermal energy networks are already used at some hospitals and universities. The systems move heat between buildings and can reduce reliance on fossil fuels.
The MTA and city will assess whether geothermal infrastructure can absorb, store and transport excess heat from the subway to nearby municipal buildings. The initial feasibility study will determine how much cooling could be achieved and the potential energy cost savings.
Radiant cooling can be 25 to 35 per cent more energy efficient than traditional air conditioning, according to the city. The technology circulates chilled water through panels on walls and ceilings or through tubing embedded in floors, allowing cool surfaces to absorb heat directly.
“Bringing down the temperature is a real challenge in a century-old system with open entrances and vents everywhere,” said MTA Chair and CEO Janno Lieber. “Together with Governor Hochul and Mayor Mamdani, we’re exploring solutions — previously untested in transit — to make stations more comfortable while helping to reduce energy costs.”
Brooklyn Bridge-City Hall also experiences significant heat from trains dwelling at the 6 line terminal.
The study will be conducted by the MTA in partnership with the New York City Department of Citywide Administrative Services, the Mayor’s Office of Climate and Environmental Justice and the Office of the Deputy Mayor for Operations.
The contract for the feasibility study is expected to be awarded this fall. If geothermal feasibility is confirmed, design work is expected to begin in early 2027.
Officials said the initiative is part of broader efforts to prepare New York’s transit system for the growing effects of extreme heat and climate change.
