Don’t use

DIY window insulation kits:

on aluminium joinery because condensation will form on the frame, and the film won’t stick properly; where children or pets are likely to damage the film; if maintaining a crystal clear view is important; if wooden frames are in poor condition, leak, are damp, or have flaking paint;

if the distance between the internal surface of the window frame and the glass pane is less than 5mm.