Lots of houses/apartments in places like Boston, etc. have old, drafty windows that landlords don’t bother to improve. Lots of hardware stores here sell kits containing double-sided tape and sheets of a special type of plastic. You surround the window with tape, place the plastic over it, then use a hot hair dryer to shrink the plastic until it’s snug. You can hardly see the plastic if you do it right, and it does a great job of dealing with drafts.