Heat recovery ventilation is an energy recovery ventilation system, using equipment known as a heat recovery ventilator, heat exchanger, air exchanger or air-to-air exchanger, that employs a counter-flow heat exchanger between the inbound and outbound air flow. HRV provide fresh air and improved climate control, while also saving energy by reducing the heating requirements. Energy recovery ventilators are closely related, however ERVs also transfer the humidity level of the exhaust air to the intake air.