Ventilation systems provide comfortable living spaces by supplying clean, fresh air from outside while exhausting stale, waste air from inside. Heat Recovery Ventilation (HRV) units are designed to enhance the amount of heat energy exchanged between these two air flows. In winter, the warm exhaust air preheats the supply air as it enters the building. In summer, the warm supply air will be cooled by the exhaust air.
Energy Recovery Ventilation (ERV) units also recover heat. However they also allow for moisture exchange between the supply and exhaust air flows. This allows for the regulation of humidity which can prevent or mitigate excessive dryness, particularly over the winter months. So Energy recovery is the combination of Heat recovery and Moisture recovery.