Philadelphia high-rise uses ice storage to stay cool and reduce electricity costs

September 29, 2015

High operating costs are the bane of a business' bottom line, so it behooves any company to take a closer look at how buildings consume energy and identify areas for improvement. One commercial property, 1500 Walnut Street, a 22-story, 270,000-square foot commercial high-rise in Philadelphia, is a great example of how thermal energy storage can be used to reduce electricity costs as well as generate income.

Ice storage helps offset the rising cost of electricity
At 1500 Walnut, the building's owner was forced to deal with the challenge of updating the building's severely outdated HVAC system without compromising the comfort of the high-rise's tenants. Thermal energy storage, specifically CALMAC's IceBank® energy storage tanks, was chosen as a strategy to help solve the owner' problems. Aging 500- and 600-ton chillers were replaced by a mixture of two smaller 300-ton chillers and thermal energy storage tanks from CALMAC complimented the smaller chillers to add flexibility to time of use purchases. Notably, the combination of energy storage and chillers were installed at the same cost as the existing system.

HVAC installation avoids interruptions to building operations
Building management and tenants were pleased that the entire retrofit was performed while the building continued to operate. Additionally, the building operator was able to master the new system in a very short amount of time, minimizing any difficulties that might arise as a result of transitioning from one HVAC system to another. This efficient transition ensures that retrofits do not come at the cost of closed offices and lost revenue.

Quick payback highlights a promising ROI
Particularly noteworthy is the fact that 1500 Walnut Street was able to see a full return on its investment within two years of installation. 1500 Walnut has seen over $40,000 in savings per month during the warmest parts of the year. Building operators make ice at night, when power is less costly, and use that ice to help supplement the chillers and cool the building when electricity rates are at their highest.

Strategic storage creates new revenue streams at 1500 Walnut
Thermal energy storage even offered additional revenue opportunities for 1500 Walnut. Local utilities are desperate to meet electricity loads on a daily basis, and commercial customers capable of assisting in this regard are often rewarded for their efforts. The more a facility depends on stored energy during peak times, the less that building will draw on the grid.

Utilities sometimes treat these buildings as "virtual power plants," according to Contracting Business. The less electricity a facility consumes, the more resources can be redirected toward the grid's most demanding users, and the more likely a utility will be motivated to reward load-shifting facilities accordingly. Thermal energy storage makes this new revenue opportunity possible for 1500 Walnut. As a result an additional $10,000 is saved annually by operating the energy storage tanks as part of a demand response system. Software determines the duration and rate of use of charging and discharging ahead of time, anticipating the next day's energy prices on an hourly basis. The stored cooling is called upon to reduce the building's cooling load during demand response events.

Multiple benefits make this high rise a success
Overall, the new chillers and thermal energy storage tanks provided 1500 Walnut Street with a system that not only offered the best net present value and significantly cut energy costs but also helped the building prepare for future changes in energy. The end results are reduced congestion on the utility grid, optimized energy storage to in turn generate revenue, reduced costs and increased reliability.