First off, there is no such thing as a house that is to tight. That's a MYTH! the problem is that in a tight house you new to manage indoor air. Your winter humidity is too high. For health reasons, it's recommended to maintain a relative humidity between 40% - 60%. That's for health. In the winter, even a RH of 40% may result in condensation on the windows other colder places. I try to maintain my house @ 35%, and in extreme cold that can be difficult.
You need to manage you air by means of a air exchanger or even a central exhaust fan.