Window Insulation Kits, like double glazing.
Shrink Film 157 cm x 182 cm with window tape 10.1 metres.
Block drafts, insulate mercifully during winter and let heaters heat properly. No experience during hot summers. Can't wait for seasonal warming. Install or remove . Hard to see if you do it well. still warms even if put up rough and desperately like I did on one or two unimportant to see places.