With standard exterior doors and skylights, the only way to reduce condensation is to lower the relative humidity of the air. The result is a dry environment that can produce annoying static electricity, dry throats and sinuses, and other irritants. If the humidity level is increased, there is the risk of excess condensation, which can lead to structural deterioration, as well as the growth of potentially harmful mould and bacteria.
High performance units are more resistant to condensation so the relative humidity inside the home can be higher without causing condensation. The air is much healthier to breathe and static electricity is greatly reduced.