Inspect the area surrounding the dryer vent pipe for cold air. Check the exterior wall hole containing the pipe. Apply a generous layer of caulk around the dryer vent hole to seal any air leaks.
Check the vent pipe for any kinks preventing airflow. Eliminate excess 90-degree bends in the vent pipe. Apply heating and cooling duct tape to the vent pipe seams.
Wrap insulation around the dryer vent pipe. Apply duct tape as needed to secure. Make sure the entire vent pipe is covered with none of the pipe metal exposed.