Exterior Doors can contribute to the majority of the air leakage in your home. Especially if the door is not properly installed, sealed, or very old.
When selecting the right type of door it is important to consider their Energy Efficiency Ratings. You will also want to make sure you have a professional install the doors, since most of them are now pre-hung and require the frame of your existing door to be removed.
When removing the frame, a proper amount of foam caulking to seal the new door frame should be done. This will help prevent air from leaking in through the opening.