Space cooling represents a significant use of energy in buildings nationwide. Requirements for cooling systems depend on the size of the spaces that need to be cooled. The simplest form of renewable cooling relies on pumping water from a cold reservoir or chilling water by pumping it through underground pipes. Other renewable thermal technologies can cool spaces using a technology called absorption refrigeration—a type of air conditioning that uses a refrigerant chemical to produce cold air from hot water. In both cases, solar thermal sources might be able to cover the entire load, or they can provide partial coverage and save money and energy as a supplement to traditional electric or thermal energy sources.