Photo: Window insulation kit The film is fixed to the window frame using double sided tape. This traps an insulating layer of air between the glass and the film which...
Some types of glazing film stick directly onto the glass with no insulating air layer and they are effective in summer when bright sunlight is a problem but they dont prevent condensation on single glazed windows in winter because the film is at the same temperature as the glass....
(every 1 ml of condensation removes 2200 Joules of heat energy from the air in the room)