The ERV is an air to air heat exchanger that has separate duct systems that draw in outside air for ventilation and distributes fresh air throughout the house. It does this by exchanging cooler indoor air to warmer humid outside by capturing cooling energy, without mixing stale exhaust and supply air.
The Energy Recovery Ventilator unit offers an advantage over standard ventilation only systems, due to its dehumidification benefits in the summer. The value of the ERV system should not be determined by cost of the system, rather the controlled ventilation from a known source of air and the improved quality of the indoor environment must be considered.