Thermal Energy Storage

The air conditioning system is the largest single contributor to a building’s energy cost during summer on-peak hours (weekdays, between Noon and 6 PM). In a typical system, the largest energy-using components are the chillers or compressors, which reject heat and provide cooled water or refrigerant to the system. Thermal energy storage (TES) systems utilize water chillers or ice-making machines to produce and store cooling capacity (thermal energy) for later use. Cooling capacity (energy) is produced and stored during the hours when electric energy demands and charges are lower, and the stored energy is used to cool the building when electric energy demands and charges are higher. Shifting cooling-related electricity consumption from on-peak to off-peak periods can result in significant energy cost savings, in addition to other benefits. Mature thermal energy storage technologies include ice storage, chilled water storage, and eutectic salts.

- Large concrete TES tanks serving multiple buildings. Crom International


  • Technology Overview: Thermal Energy Storage (TES)
    October 17, 2013
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    Thermal Energy Storage (TES) refers to the storage of cooling capacity in order to shift electrical demand to off-peak hours. Typical thermal energy storage systems work in conjunction with air distribution systems and rely on water chillers or ice-making machines to produce cooling capacity.

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  • Technology Overview: Chilled Water TES Systems
    October 16, 2013
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    Chilled Water systems are one of the most popular options for thermal energy storage (TES). Chilled water systems are appealing for many applications because they are less complex and have lower operating costs than alternative technologies, but require more physical space as they offer lower storage density than other options.

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  • Technology Overview: Ice Storage TES Systems
    October 16, 2013
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    Ice storage thermal energy storage (TES) systems rely on ice instead of chilled water as a storage medium. Ice storage systems are less often used than chilled water systems due to being more complex and less efficient, but offer the densest storage capacity. Ice storage tanks are about 75% smaller than chilled water tanks.

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  • Technology Overview: Rooftop Unit TES Systems
    October 16, 2013
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    Thermal energy storage (TES) systems can be used with commercial and residential packaged rooftop units (RTUs), to shift energy use to off-peak periods.  RTU-TES systems can be designed for new construction or retrofit applications.

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  • Technology Overview: Eutectic Salts TES Systems
    October 14, 2013
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    Eutectic salts Thermal Energy Storage (TES) systems use a phase change medium instead of ice. Eutectic salts have a higher freezing point temperature than water. The phase change material is encapsulated in plastic containers that are stacked in the storage tank as water is circulated around them.

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  • Design Brief: Central DHW Systems in Multifamily Buildings
    January 5, 2010
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    Domestic water heating (DHW) accounts for a significant share of multifamily building energy use, especially in California's coastal towns. While each new construction project will have a different ratio of energy end uses, one can look at the existing building stock to get an idea of how much is attributable to DHW systems. According to the Department of Energy's Residential Energy Consumption Survey (RECS), DHW accounted for around 32% of overall energy use for existing multifamily units in the late 1990's.

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  • Design Guidelines: CoolTools Chilled Water Plant
    December 28, 2009
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    Many large buildings, campuses, and other facilities have plants that make chilled water and distribute it to air handling units and other cooling equipment. The design operation and maintenance of these chilled water plants has a very large impact on building energy use and energy operating cost.

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  • e-News #67: Cool Thermal Energy Storage
    October 9, 2009
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    In California, electrical  power demand reaches its peak during the hottest summer days, mostly due to air  conditioning loads, which account for almost 28% of California's peak electrical demand. A cool storage  thermal energy storage system (TES) provides a means for shifting all or part  of a facility's cooling energy use to off-peak hours, when energy costs are  lower and cooling systems can potentially run more efficiently. A TES system  uses cooling equipment at night to remove heat from a thermal reservoir of  chilled water or ice, which can then be used for space cooling throughout the day.

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  • e-News #65: Saving Lives, Saving Energy
    June 25, 2009
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    Ongoing construction and major retrofitting of hospitals in California, driven by aging facilities and the demand for new medical technologies, offers an unprecedented opportunity to dramatically improve the energy performance of healthcare facilities for decades to come.

     

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  • Case Studies: Tahoe Center for Environmental Sciences
    June 12, 2009
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    The Tahoe Center for Environmental Sciences (TCES) is a three-story, 45,000 ft2 building on Sierra Nevada College's Lake Campus that demonstrates how an ambitious project team can successfully reduce energy usage by implementing a variety of innovative mechanical designs at minimal additional first cost.

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  • e-News #57: Designing Office Buildings to Perform Better Than Title 24
    December 1, 2006
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    As designers and developers of new office buildings in California know, designing a building to meet the state's Energy Efficiency Building Standards isn't a goal-it's the law.

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