Air conditioning of commercial buildings during summer daytime hours is the largest single contributor to electrical peak demand. As more air conditioning is needed to maintain comfortable temperatures, the increased demand for electricity adds to the load already created by many other sources. This requires the electric suppliers to bring additional, more costly generating equipment on line to handle this increased demand. Commercial uses are charged more for this “On Peak” energy, either in the form of higher energy charge (kWh) or “Demand Charge” which is based on their highest on-peak demand (kW) for electricity. An effective way to combat these “On Peak” energy charges is to utilize, “Off Peak Cooling” (OPC).
The electric supplier’s generating capacity is typically under-utilized at night, and consequently, its rates are lowest then. A Thermal Energy Storage (TES) system takes advantage of low cost, off peak electricity, produced more efficiently throughout the night, to create and store cooling energy for use when rates are higher, typically during the day.
Ice Storage systems utilize a packaged chiller to produce ice during the night and store it in modular tanks. This stored ice provides cooling the following day to meet the building’s air conditioning load requirement. These systems not only dramatically reduce the use of peak period, high-cost energy, but they can also reduce total energy usage by 10%.
An Ice Storage system reduces the size of the building’s air conditioning equipment which can include chillers, cooling towers, pumps, and electrical service. For instance, with an Ice Storage system, a 100-ton chiller is able to do the job of a 200 ton chiller in a conventional system, which can add up to significant savings. The building occupants don’t notice any temperature difference, while building owner saves both money and energy.
So what type of building can benefit most from Thermal Energy Storage? Offices, schools, hospitals, supermarkets, restaurants, and hotels are just a few examples. When these buildings incorporate the system during the design stage, thermal energy storage has initial costs comparable to traditional HVAC systems. Many installations achieve a net initial cost savings when compared to other choices. If Ice Storage is incorporated during an expansion or retrofit, the upfront costs for the tanks are rapidly offset by the savings in purchasing energy at the lowest possible rates. Most organizations see full payback in two to five years.
Giving “ice a try” can not only benefit the building owner, but also the energy providers, and the environment. Building Owners will see reduced energy and maintenance costs while seeing an increase in property value. Energy Providers will reduce peak electrical demands allowing them to produce more electricity at increased efficiencies while saving precious natural resources. Reduced fuel usage means less polluting emissions are released into the atmosphere, which is also a great benefit for our planet.
Ice storage is being used throughout the United States in large buildings such as libraries, universities, and office buildings. The Google office in New York City has recently transitioned to Thermal Energy Storage, as well as the Rockefeller Center. Here in North Carolina, Brady has installed Thermal Energy Storage systems in several buildings in Greensboro, including the J. Douglas Galyon Depot, Centenary United Methodist Church, Lawndale Baptist Church, and the Green Valley Office Park Business Center. Brady also installed systems in Johnston County Schools in Johnston County, North Carolina. Currently, thermal energy storage is used in the cooling systems of over 4,000 commercial buildings in more than 35 countries.
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