How   It Works The principle of air conditioning always comes down to the same: absorb energy in one place and release it in another place The process requires an indoor unit, an outdoor unit and copper piping to connect both. Through the piping the refrigerant flows from one unit to another. It is the refrigerant that absorbs the energy in one unit and releases it in the other. 1) Indoor unit A fan blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs the heat from the air and cooled air is blown into the room. 2) Copper piping The refrigerant circulates through the units and the piping and takes the heat from the indoor unit to the outdoor unit. 3) Outdoor unit Through compression, the refrigerant gas is heated and its boiling point increases. In the outdoor unit the obtained heat through compression is released to the outdoor air by means of a fan which blows the outdoor air over a heat exchanging coil. 4) Refrigerant The liquid refrigerant flows back to the indoor unit. 5) Indoor unit Back in the indoor unit, the refrigerant is decompressed and thus enabled to extract heat from the indoor air. Heat Pump Technology Heat flows naturally from a higher to a lower temperature. Heat pumps, however, are able to force the heat flow in the other direction, using relatively little power. Thus heat pumps can transfer heat from the air into a building. They can also be used for cooling, transferring heat in the opposite direction away from a building to surroundings at a higher temperature. Air conditioning units simply remove heat from the air via copper piping filled with refrigerant – very similar to a refrigerator.