As outside air enters the ERV, it is also filtered by the heat exchange material rated as a MERV 12 filter to capture contaminants. After passing through the patented dual purpose heat exchanger, the warmed fresh air is distributed through-out the building. Up to 99% of the heat energy from the outbound stale air is transferred to the incoming air flow. This creates incoming air temperature closer to the temperature already inside the home, therefore requiring less energy to condition (warm or cool) the new air. This patented filtration material is why the UltimateAir ERV is less expensive to own and operate.