Why NYC’s Subway Heat Is a Problem

New York City subway stations can become painfully hot during the summer. Now, city and state officials are studying whether that unwanted heat can be captured and reused instead of simply being released into the air.

The proposed system could cool subway platforms while supplying heat to nearby municipal buildings during colder months.

The average temperature inside Brooklyn Bridge-City Hall subway station reached 96 degrees Fahrenheit last summer. Mayor Zohran Mamdani described the stations as places that can feel like “underground saunas” during August.

Mamdani made the comments Monday at Chambers Street station, where he joined New York Gov. Kathy Hochul and other officials to announce the study.

The city and state are examining a thermal energy network, or TEN. The system uses water pipes and heat pumps to move thermal energy between buildings and other sources of excess heat.

TENs can collect heat from places such as buildings, wastewater systems and underground transit stations. That energy can then support heating and cooling needs elsewhere.

An $800,000 Feasibility Study

Instagram | nycmayor | Mayor Zohran Mamdani joined state leaders to launch a study repurposing excess subway heat for heating and cooling.

New York plans to spend $800,000 on a study to determine whether subway heat can be captured and stored for later use.

The study will focus on Chambers Street and Brooklyn Bridge-City Hall stations. Researchers will examine how much cooling the system could provide on subway platforms and how much the city could potentially save in energy costs.

The proposed setup would move excess heat through pipes to geothermal boreholes. The underground storage system could hold the heat until colder months, when it could help warm nearby municipal buildings.

The contract is expected to be awarded this fall. If the study finds that geothermal storage is practical, design work could begin in early 2027.

Metropolitan Transportation Authority Chair and CEO Janno Lieber called the idea a potential “win-win.” Cooler subway stations could improve conditions for riders, while the city could reduce energy costs.

A Broader Energy Plan

The project is tied to a major renovation of Chambers Street station, one of the oldest stations in New York City’s subway system.

Funding for the renovation comes from revenue generated by New York City’s congestion pricing program. That creates an opportunity to include new energy infrastructure as part of the station work.

Hochul said the project shows what cooperation between city and state governments can achieve. She also said the approach could provide benefits for millions of subway riders.

Thermal energy networks are not new to New York City. Lieber noted that similar systems are already operating at St. Patrick’s Cathedral and the New York Botanical Garden.

Instagram | news12bk | NYC is scaling its proven thermal energy concept to subways, creating a potential model for global transit system.

The subway project could take the concept into a much larger public transit setting. If successful, the model could also interest other cities with extensive underground transit systems.

Johanna Partin, founding principal of Transformative Strategies Consulting, said cities can use waste heat as an overlooked energy resource. She is also working with the city of Boston on research into thermal energy from waterways, data centers, transit systems and wastewater treatment facilities.

Partin said the approach could turn a common problem, such as an overheated subway platform, into a useful energy source.

What Happens Next

The feasibility study will determine whether the proposed system can work technically and financially. It will also help officials understand how much subway cooling and building heating the system could provide.

If the results support geothermal storage, design work could start in 2027. The project could then offer New York a practical way to connect transit infrastructure with cleaner heating and cooling systems.

The plan offers a different way to think about extreme subway heat. Instead of treating summer heat only as a problem, New York is examining whether it can be captured, stored and used when temperatures fall.

The upcoming study will show whether that idea can work on a larger scale. If it does, subway stations could play a new role in the city’s energy system while helping create cooler platforms and more efficient municipal buildings.