The cooling is often reached via a refrigeration cycle, but occasionally evaporation or free cooling is utilized. Air conditioning units can also be produced determined by desiccants (substances which clear away moisture in the air). Some AC devices reject or shop warmth in subterranean pipes.[2] Central cooling vegetation are utilized https://docs.google.com/spreadsheets/d/1sFkX-195bzbspltn6kI7pJAwHC_IWJIWy0giWMghe84