Air conditioning (often referred to as aircon, AC or A/C) is the process of altering the properties of air (primarily temperature and humidity) to more favourable conditions, typically with the aim of distributing the conditioned air to an occupied space to improve comfort. In the most general sense, air conditioning can refer to any form of technology, heating, cooling, de-humidification, humidification, cleaning, ventilation, or air movement, that modifies the condition of air. In common use, an air conditioner is a device (most commonly a home appliance or automobile system) that lowers the air temperature. The cooling is typically done using a simple refrigeration cycle, but sometimes evaporation is used, commonly for comfort cooling in buildings and motor vehicles. In construction, a complete system of heating, ventilation and air conditioning is referred to as "HVAC". Air conditioning can also be provided by a simple process called free cooling which uses pumps to circulate a coo...