Window insulation refers to methods used to reduce heat loss or gain through windows, improving energy efficiency in buildings. This can be achieved through various techniques, such as using double or triple-glazed glass, which traps air or gas between panes to create a barrier against temperature changes. Another common approach is applying window film or using insulating curtains, which can help block drafts and reduce heat transfer. Proper insulation not only enhances comfort but also lowers energy bills by minimizing the need for heating and cooling systems to work harder.