It is quite simple to ventilate a room that has multiple windows, particularly if the windows are located on opposite walls. Just open the windows on a breezy day, and let the breeze circulate new air into the room to replace the stale air or musty odors. There are several methods to use when a room only has one window; these methods also work to pull hot air out of a room and replace it with cooler air from outdoors.
Open doors and windows
Open both the door and the single window in the room. Also open other doors and windows in the house to create additional air flow.
Turn on ceiling fans
Turn on any ceiling fans in the house to increase air flow throughout the house. While ceiling fans do not actually create cross ventilation, they do increase the movement of air in a room.
Use window fans
Place a window fan blowing into the interior of a room to pull cooler air into the house. Cooler air from the home's interior can be blown into the room with a fan in the doorway.
Install an attic fan or whole house fan
These powerful fans pull air through the windows of a house and expel interior air out through the top of the house.