District heating/cooling have been used for the past 200 years, first appearance was in the 14th century in Chaudes-AiguesCantal in France where warm water from springs was distributed through wooden pipes to households. District Cooling is the centralized air conditioning method that uses chilled water that is transferred through underground pipelines to buildings to be used as a mean of cooling of the indoor air within a certain district (certain block within a city). The water that is used will be seawater. The cold water from the main District Cooling Unit (DCU) goes through heat exchanger within the smaller DCU to exchange heat between the cold water coming from the main DCU and the cold water within the smaller DCU. The water is then re-cooled for distribution to the buildings through a secondary pipeline.