A Manhattan office building began freezing water at night; the stored ice now helps cool it during peak summer demand

Four floors below one of Manhattan's most iconic office buildings, something strange happens every night. Machines silently freeze half a million pounds of water into ice, roughly three city buses' worth. By morning, the ice has melted, and the chilled water cools the building throughout the day. CBS News reported in June 2025 that this is how Eleven Madison Avenue keeps itself air-conditioned, based on interviews with the company that installed the system. A study conducted by the National Energy Assistance Directors Association and published in May 2025 revealed that the average summer household cooling bill in the United States for June through September was estimated to be $784. The same CBS report cited this figure as the highest summer average in the 12-year history of the organization's records on cooling expenses.

Meet the "ice battery"

Manhattan's cooling system is called an ice battery, which accurately describes how it works. While a phone battery stores energy in the form of electricity, the ice battery stores "coolness." Holly Paeper, president of Trane Technologies' Commercial HVAC Americas business, which installed the Eleven Madison Avenue system, told CBS News the building freezes water at night, when electricity is cheap, and runs on that ice during the expensive afternoon hours.


"So, when everyone else is using their electricity in the middle of July to cool their building or to cool their homes, it's a big draw on the grid," Paeper said, according to the CBS report. "This building won't draw from that because it made its ice last night." Trane Technologies says the buildings with the system can save 40 percent on cooling, as stated in the company's own technical documentation.

The bigger grid problem this solves

The goal is to protect the power grid during periods of extreme heat. As of 2018, the most recent global figure publicly available, air conditioning accounted for 20 percent of total electricity consumption in residential and commercial properties globally, according to the International Energy Agency. But on the hottest days, that share can be more than 70 percent of electricity consumed during peak afternoon hours, a separate 2023 IEA report found. That spike is what concerns Dr. Patrick Shamberger, an associate professor of materials science and engineering at Texas A&M University. Building additional power plants, he explained, requires a lot of capital investment that rarely gets used. Ice batteries are a way to balance demand without adding capacity that sits idle most of the year.

Texas A&M is trying to make the tech even better

The freezing process itself actually requires a huge amount of energy, which is why Shamberger's team is trying to find materials that don't have to reach the temperature of freezing water but can still effectively retain their cooling potential. A Texas A&M feature on the team's research explains that scientists are combining water with other elements and molecules to hit target freezing points anywhere from 0 to 20 degrees Celsius. That range matters because the ideal storage temperature depends on local electricity pricing patterns and climate, not on the temperature the building itself is ultimately cooled to; what's cost-optimal to freeze in Texas isn't necessarily cost-optimal in Nevada or Wisconsin, Shamberger told CBS News. The team's findings are detailed in a paper published in The Journal of Physical Chemistry, which provides research support for the approach.

Why this should be on your radar

Ice battery systems are currently used in large commercial and government buildings. Trane told CBS News the company has installed around 4,000 systems worldwide, out of an estimated six million commercial buildings in the U.S., still a small fraction. For now, ice batteries are changing how some office towers and large buildings handle summer heat: frozen water, timed to reduce strain on the power grid and lower costs.