1.   A heat recovery ventilator can bring in fresh air and warm it with the heat from the exhausted stale air.

2.   However, you will also have to install louvered openings at each end of the attic so that the exhausted air can escape easily to the outside.

3.   That is because modern houses do not have intake fans to replace exhausted air.

4.   The heat of the exhausted air is transferred to the incoming air, so there is less loss of heat, and the ventilation is constant.