A friend of mine is about to pull the trigger on a device called an Ez-Breathe. its basically a squirrel cage fan in a box that sits on your basement floor and ventilates cool damp air from the floor to the outside.It claims there is no need for a fresh air intake. It relies on cracks around windows and doors(not very scientific) Worst part is it cost about $1500. A lot for a $50 fan in a box. It does have a humidistat in it so it turns off if tha air reaches a certain humidity. I think a better move would be to invest a few more dollars in a good air recovery system that also extracts the heat or cold from exiting air and provides a dedicated fresh air intake.