A chiller is a unit which remove heat from water and the chilled water is hereafter used for air conditioning in the entire building. Chillers are commonly seen in large-size buildings from commercial- over industrial- to institutional facilities. Chillers are typically located in the basement or on the roof top and can be either water- or air cooled. Water-cooled chillers will use cooling towers, whereas air-cooled versions will blow the hot air across its condenser to disperse the unwanted heat into the atmosphere or recovered for heating purposes. Water-cooled systems are considered as the more efficient solution.