Philadelphia skyscraper cools with ice tanks

This 22-story building in Philadelphia is using Calmac’s IceBank tanks to cool the high-rise structure during peak energy times. Calmac says the building has become a “virtual power plant.” 

A 22-story, 270,000-square-foot high-rise building on Walnut Street in Philadelphia has successfully housed tenants for 84 years.

However, the building’s aging HVAC system was starting to fail and make some of them uncomfortable.

Calmac, a manufacturer of energy-storage systems, was brought in to solve the problem. The company installed one of its IceBank tanks and two 300-ton chillers. Calmac officials report that new tanks will assist in saving the building $40,000 in energy costs per month during the warmer months and generate $10,000 of revenue per year.

“The system we had in place was an energy hog that was affecting bottom-line revenue for the owner,” said Gene O’Donnell, the building’s manager. “There was no question we needed a new system, but we also couldn’t burden the tenants while we installed it.”

The new thermal energy storage system, which was installed at the recommendation of Tozour Energy Services for the same cost of the existing outdated system, allows ice to be created at night, when power is less expensive and generated more efficiently. It is then used the next day to cool the building during peak demand hours, which has reduced operating costs. The thermal energy storage tanks were also paired with Viridity Energy’s VP Power software to provide flexibility.

With this upgrade to the building controls, Calmac’s tanks are able to function as a part of a real-time demand-response system that uses data from the utility company.

“Viridity Energy can forecast where prices due to congestion will be for the next day on an hour-by-hour basis and provide a schedule to the building operator through the building-automation system, which the ice system is tied into to make ice or burn ice,” said H.G. Chissell, regional vice president for Viridity Energy. “When they are using ice they are not using their chillers and their load drops. We can then make sure that the grid operator knows that this load is dropping during these hours and they don’t have to go to a power plant. The grid operator diverts the income or the money to the building.”

Mark MacCracken, CEO of Calmac, said the Philadelphia high-rise has become a “virtual power plant.”

 “If the utility company can pay a building to reduce their load at a cheaper price than it costs them to generate the extra electricity, they would much rather do that. It becomes a win-win for the building and the utility company,” he said.