Refrigeration refers to any method of reducing heat (technically, moving heat from one place to another), for various purposes. One of the simplest methods involves fanning, to produce a breeze, which may be done with either bare hands (which is of very little effectiveness) or with simple tools designed for the purpose, made from any number of natural materials. This is most commonly used merely to keep an individual cool on a hot day, though simple fans eventually led to the invention of bellows, which are used most commonly in forges, by smiths, or by kilners.
For purposes of larger scope, particularly keeping food cold, two methods have been used since the time of Connor and Brigid. One method involved storing food in waterproof containers, which would be tethered and stored underwater, usually in a river. Also at some point in the first century, people began harvesting ice from mountaintops, which would be stored underground in yakhchals. The pits are well-insulated to prevent heat from entering, and are covered by buildings which may capture wind and/or water to further lower the temperature in the pit. (When the villages of the Northern Alliance were founded in the latter half of the ninth century, people there began harvesting ice in winter, without the need to climb mountains to obtain ice, as is necessary in other villages, which don't generally have true winters.)
These early methods of refrigeration have been increasingly replaced since the Coming of the Order, using spell devices called refrigerators, which were first created in LY 822. Prior to the Coming, such devices were essentially unknown outside of Sorret. However, since the end of the Coming, they have become more common in most homes, as well as being used by spirit-makers for the production of alcohol, and by the producers and distributors of various foods, particularly ice cream. A modified version of the spell device has also come to be used for air conditioning, to keep homes cool.
In 916, piston pumps are beginning to be used to compress carbon dioxide, to produce "dry ice," which may be used for transporting goods that must be kept cool, more effectively than with early methods of refrigeration, and without the need for magic.