Air circulation can reduce mould and condensation problems in closets or in unused rooms; but it's not a way of solving serious moisture issues.
Excess moisture affects millions of homes, even modern ones. And the first step to control it, is to know where it comes from and how it moves into the living space or into the home's envelope (see Box below). Ventilation is just a way of minimizing moisture problems.
Structural moisture issues should be solved at their source: flashing defects, roof leaks, plumbing leaks, lack of proper surface and underground draining, cracks and holes in walls, and so on...
»» Indoor sources of moisture: cooking, showering, dishwashing, dryers venting indoors and people...
You should have exhaust fans in each bathroom and in your kitchen, and your clothes dryer should be vented to the outdoors.
»» Outdoor sources of moisture: rain and snow water, moist air, water vapor.
»» Outdoor (or indoor) moisture moves into the walls, floors and ceilings through leaks and flashing defects, cracks, holes and openings or by capillary suction. Structural moisture problems should be fixed at their source.
See: Home Moisture Control
Air circulation & Moisture
Air circulation may help prevent or eliminate minor moisture problems, in some rooms or parts of the house; natural and mechanical ventilation can help control mold and condensation in closets and unused rooms, or corners or patches on walls behind furniture.
In other words: don't cut off air circulation and heating supply to closed and unused rooms... Air circulation can eliminate mold and mildew growth.
Open the windows when the outside temperature allows it, and the outside air is dry; open drapes and curtains, and run the furnace fan...
During the summer use ventilation fans or dehumidifiers.
Dehumidifiers are typically ineffective during the winter, but they can be useful in the summer months in rooms – basements, crawlspaces - where ventilation is difficult to achieve.
For customer reviews and prices at Amazon see: Dehumidifiers.
Air Leaks and Tight Homes Ventilation
Air infiltration - through cracks, openings, holes... - is not a way of solving moisture problems or of getting fresh air.
Since it is uncontrolled, air infilration may over-ventilate the house during severe weather conditions, and is not a good source of fresh air; ultimately, air infiltration is responsible for higher energy costs and low indoor air quality (due to pollutants hidden in the walls, floors and foundations) and can help moisture to enter the walls, floors and ceilings.
Air leakage is never a good way of getting fresh air and ventilation; you will never be able to control it. Modern energy-efficient homes use an airtight approach...
See on these issues:
Air tight homes, leaky homes and energy efficiency
Air Sealing: Solving Moisture Problems