This model ventilator may be the best choice if you have a larger home and live in a hot, humid summer climate. It will help transfer indoor heating or cooling energy to the incoming air so you can have fresh air even on extreme days. It's a far better fresh solution than opening a window and letting your energy dollars fly out.
If you have a large home and live in a colder winter climate with moderate or low summer humidity and would like to keep the air inside your house fresh, use an HRV. Its special crossflow core transfers indoor heat energy to the incoming air so you can have fresh air even on extreme, cold days.