Bathroom renovation is a great time to consider installing new exhaust fans to remove odors, moisture and mold spores. Many bathroom fans can only lead to the space between the ceiling joists, creating an environment that can damage the walls and ceiling for mold and moisture. Make sure your new fan is fully accessible to the outside of your home.

 
Unfortunately, even properly installed fans can push moist air out of doors. A smart solution to this problem is a heat exchange ventilator that uses output air to heat cold air. The unit costs about 250 RMB, twice as much as a standard fan. Whatever fan you have, avoid the switch; it's easy to forget to turn it off. Replace the fan unit with a timer switch or, better yet, purchase a new fan unit with a motion or humidity sensing switch.