Brine is used as a secondary fluid in large refrigeration installations for the transport of thermal energy from place to place. Most commonly used brines are based on inexpensive calcium chloride and sodium chloride. It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine is at the concentration of 23.3% NaCl by weight. This is called the eutectic point.