Why should I use an air to air heat exchanger (VAM) in a central AC system?

The use of air to air heat exchangers (VAM) for heat recovery concerning heating and cooling, reduces the required capacity of air conditioning units, as the incoming air(fresh) in the unit is pre-air-conditioned and so low cost operation can be achieved. By installing an air to air heat exchanger (VAM) in a central AC system we cut down on the energy consumption as much as 75%, depending on the environment conditions and the quality of the heat exchangers (VAM).