Heat Recovery Ventilators (HRV) exchanges air from inside your home with that of the air outside. While doing this it pulls the exhaust air to condition the air coming in, saving energy. In an air sealed home the HRV allows you to control where the air you breathe in your home comes from and filter it if you so desire.
Continuous Fan Installation
When a home is air sealed to a certain degree, sometimes a continuous exhaust fan is required to ensure healthy air inside the home. Continuous fans also help with moisture issues. They act like an HRV but they don't filter air nor do they recovery the energy invested in the conditioned air inside your home.