Chilled water is a commodity often used to cool a building's air and equipment, especially in situations where many individual rooms must be controlled separately, such as a hotel. The chilled water can be supplied by a vendors, such as a public utility or created at the location of the building that will use it, which has been the norm.
Chilled water cooling is not very different from typical residential air conditioning where water is pumped from the chiller to the air handler unit to cool the air.
Regardless of who provides it, the chilled water (between 4° and 7°C (39-44 °F)) is pumped through an air handler, which captures the heat from the air, then disperses the air throughout the area to be cooled.
The condenser water absorbs heat from the refrigerant in the condenser barrel of the water chiller, and is then sent via return lines to a cooling tower, which is a heat exchange device used to transfer waste heat to the atmosphere. The extent to which the cooling tower decreases the temperature depends upon the outside temperature, the relative humidity and the atmospheric pressure. The water in the chilled water circuit will be lowered to the Wet-bulb temperature or dry-bulb temperature before proceeding to the water chiller, where it is cooled to between 4° and 7°C and pumped to the air handler, where the cycle is repeated. The equipment required includes chillers, cooling towers, pumps and electrical control equipment. The initial capital outlay for these is substantial and maintenance costs can fluctuate. Adequate space must be included in building design for the physical plant and access to equipment.