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Philadelphia, PA, High-rise HVAC System Renovated with Thermal-energy Storage Tanks

Integration assists in saving the 84-year-old building up to $40,000 a month in energy costs and generating $10,000 of annual revenue through utility incentive programs.

A 22-story, 270,000-sq-ft high-rise commercial building located in Philadelphia, PA, recently installed thermal-energy storage tanks. Facing a failing HVAC system and declining tenant satisfaction, building owners decided to install the tanks and two 300-ton chillers.

The new CALMAC IceBank tanks are assisting in saving 1500 Walnut St. $40,000 in energy costs per month during the warmer months and generating an additional $10,000 of revenue per year. The upgrades have helped turn the building into a “virtual power plant,” prepared it for the smart grid and were installed at the same cost of the existing outdated system.

“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 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, 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 significantly reduced operating costs. The thermal-energy storage tanks were also paired with Viridity Energy’s VP Power software to provide additional 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 utilizes 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, Vice President, Northeast Region and Strategic Accounts at 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.”

“1500 Walnut has turned into a ‘virtual power plant,’” said Mark MacCracken, CEO of CALMAC. “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.”

When referring to the additional revenue, O’Donnell added, “We don’t need one square foot of space in this building to make this money, and the tenants in this building see no change at all."

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