A window insulation film functions as a barrier between your apartment and the windows. A window insulation film kit will generally include a plastic shrink film that should be applied on the inner side of the window using double-sided tape. Heat the plastic film using a hairdryer to remove wrinkles and shrink it.
While it doesn’t quite offer the elegance one would like to see, bubble wrap is an excellent way to insulate the windows in your apartment. Look for bubble wrap with larger bubbles because they provide better insulation compared to the smaller ones.
Spray a mist of water on the inner side of your window pane and press the wrap on to the window such that the bubbled side touches the moist window. Next, seal the edges using double-sided tape. Be careful, though. When you take the bubble wrap off, you might end up peeling off the color too.