Energy recovery ventilation is a system that helps your home stay warm in the winter and cool in the summer. It does this by taking the warm or cold air from inside your home and exchanging it with the outside air. In the winter, the warm air from inside your home is sent outside and the cold air from outside is brought in to keep your home warm. In the summer, the opposite happens - the hot air from outside is sent out and the cool air from inside is brought in to keep your home cool. This makes your house more comfortable and can also save you money on your energy bills.