Due to the home ventilation system , Passive Houses are effortlessly clean, pollen-free, dust-free, and eliminates moisture and odors in places where they most occur. Normally, for you to achieve all of what is listed above, you would need to opened up your windows. By opening up the windows, it would result in heat losses which is “greater than the total energy demand.”
Thus, heat recovery from PHs are very essential for that exact reason. According to Active for more comfort: The Passive House, “heat recovery reduces ventilation heat losses considerably because inside the heat exchanger, heat from the warm exhaust air is passed on to the cold fresh air.” As a result, you’d get great temperature control, because often, it would bring incoming air almost up to room temperature with little energy used. However, note that both the air ducts and supply air ducts in the heat exchanger are leak-proof. Fresh air and exhaust air are never assorted.