Refrigerant based systems are the most energy efficient air conditioning systems and generally operate using split or multi-split air conditioning units. This means that there will be a unit mounted in the room to be cooled, usually a fan coil, and an external unit, a condensing unit or heat pump unit mounted outside the building. Refrigerant is pumped round connecting pipework from the compressor in the condensing unit to the room unit where it expands causing a refrigeration effect. The room air is blown across the coil causing it to cool. The refrigerant carrying the rejected room heat is pumped back to the external unit where it is condensed, giving off the heat to the outside air via a dry coil and fan. The refrigerant is compressed again into liquid by a compressor and the cycle goes on.
