http://www.adencn.com/energy-r....ecovery-ventilation/
High volume energy recovery ventilation systemn (ERV) is the process of energy recovery in big residential and commercial HVAC systems, by exchanging energy from the exhausted air of a building or space, to process ventilated air entering the room. In the hot season, the system precools and dehumidifies the fresh air, humidify and preheat in the cold season.