How to Make Your House Warmer by Adjusting the Storm Door Sweep: Slow drafts with a one-minute door sweep adjustment. Stop drafts and save energy by adjusting the bottom sweep on your exterior doors. It usually takes less than five minutes. Cut drafts by adjusting the door sweep
Soundprofing door. Most obvious fix is to ~$35 add door sweep, If gap to ground >0.75" need to build out bottom of door. In addition to this, could consider (1) replacing door with thicker exterior door, and/or (2) adding rubber gasket at door-door interface.