Bubble wrap is a great packing material but, it is also a great insulator. If you have windows that are letting in too much cold you can use bubble wrap to stop it.
Best if Detachable
To get the best results and most flexibility you should build frames to fit inside the window frames. The frames can either be used to support the bubble wrap against the window or they can have the bubble wrap attached. The attached bubble wrap and the frame is effectively a detachable insulation panel. Because it covers the window, it helps to cut the drafts coming in around the window.
If you are only interested in window insulation for the glass elements of the window, fitting bubble wrap is very simple.
Cut the bubble wrap to the size of the windowpane.
Spray the glass lightly with water and apply the bubble wrap's smooth side to the glass.
Smooth it over and squeeze out as much of the water as you can.
As the water dries the bubble wrap clings tighter to the glass and will stay in place for months.
To remove it, simply peel the bubble wrap off the windowpane.