Clockwise in the summer, counter clockwise in winter. In the summer heat rises, so you run your fan clockwise to force hot air down to cool the room faster. Cold is drawn to heat, it is cooler at floor level. In winter it is warmer at floor level so you run your fan counter clockwise to draw hot air toward ceiling. But if you have central air and heat, with outlet grills in the ceiling this should be reversed. Heat and Cold will be coming from the grills in the ceiling. Then there is no need to run a fan at all if you have central air and heat. Air from the ceiling grills is drawn back to the unit. This is referred to as return air to unit, this keeps air circulating in each room.