A Heat Recovery Ventilator (HRV) saves energy by transferring heat between the stale air exhausted to the outside and the fresh air that is brought inside. This makes sure that when the ventilator is bringing in outside air, the heat stays inside the house in the winter or outside the house in the summer. The Energy Recovery Ventilator (ERV) saves energy by transferring both heat and moisture. Both the HRV and the ERV are Honeywell Whole-House Ventilation Systems that provide the ventilation and allow you to save energy. Check with your local contractor to find out which one is right for you.