Installing a bathroom fan that vents to the outside provides a good option for bathroom ventilation. While some older homes use windows, they are less effective at reducing humidity and lower the heating efficiency of the room. A third option for reducing humidity is installing a portable dehumidifier, although this option does not eliminate unpleasant odors.
Most bathroom vent fans install through the ceiling where there is nearby electrical power available from the light. Some units combine a light and vent in a single unit. While do-it-yourself homeowners might be tempted to vent the bathroom into an unheated attic, this moves the moisture to the adjacent space where it causes mold to grow. Options for ducting the fan include through the roof or wall. Owners can install a direct vent fan in bathrooms that have an exterior wall, but this usually requires installing a separate electrical line.
If the bathroom has a window, opening it increases ventilation. However, windows are less effective than vents and condensation on the cold glass often increases moisture problems. If facing the decision between installing a fan or a window, the fan is generally the best choice.
In small bathrooms without ventilation, a portable dehumidifier helps to prevent the growth of mold. These units do not require electrical wiring or cutting through the roof.