Editing Energy storage (section)

=== Air conditioning ===
{{Main|Ice storage air conditioning}}

[[Thermal energy storage]] (TES) can be used for [[air conditioning]].<ref name="Calmac" /> It is most widely used for cooling single large buildings and/or groups of smaller buildings. Commercial air conditioning systems are the biggest contributors to peak electrical loads. In 2009, thermal storage was used in over 3,300 buildings in over 35 countries. It works by chilling material at night and using the chilled material for cooling during the hotter daytime periods.<ref name="NYTimes-2014.04.21" />

The most popular technique is [[Thermal energy storage#Air conditioning|ice storage]], which requires less space than water and is cheaper than fuel cells or flywheels. In this application, a standard chiller runs at night to produce an ice pile. Water circulates through the pile during the day to chill water that would normally be the chiller's daytime output.

A partial storage system minimizes capital investment by running the chillers nearly 24 hours a day. At night, they produce ice for storage and during the day they chill water. Water circulating through the melting ice augments the production of chilled water. Such a system makes ice for 16 to 18 hours a day and melts ice for six hours a day. Capital expenditures are reduced because the chillers can be just 40% – 50% of the size needed for a conventional, no-storage design. Storage sufficient to store half a day's available heat is usually adequate.

A full storage system shuts off the chillers during peak load hours. Capital costs are higher, as such a system requires larger chillers and a larger ice storage system.

This ice is produced when electrical utility rates are lower.<ref name="DistributedEnergy.com" /> Off-peak cooling systems can lower energy costs. The U.S. [[Green Building Council]] has developed the [[Leadership in Energy and Environmental Design]] (LEED) program to encourage the design of reduced-environmental impact buildings. Off-peak cooling may help toward LEED Certification.<ref>Air-Conditioning, Heating and Refrigeration Institute, Fundamentals of HVAC/R, Page 1263</ref>

Thermal storage for heating is less common than for cooling. An example of thermal storage is storing solar heat to be used for heating at night.

Latent heat can also be stored in technical [[Phase-change material|phase change materials]] (PCMs). These can be encapsulated in wall and ceiling panels, to moderate room temperatures.