Swapping out old, single-glazed windows with high-performance dual- or triple-pane units is costly. Moreover, it is often not allowed in historic buildings. Architectural historians insist on maintaining the appearance and character of windows in classic old buildings, irrespective of their performance.
According to the U.S. Department of Energy, around 30 percent of the energy used to heat and cool our homes is lost through inefficient windows, even though windows often make up less than 10 percent of the surface area of a house.
A less costly possibility, rather than replacing inefficient windows, is to install an insulating window film. Glazing films have been around for more than 50 years, with high-performance films only in the past decade. They have evolved along with the great gains in window technologies. Coatings and films have become standard in high-quality windows. The large choice of offerings can yield greater or lesser heat gain, visual clarity, ultraviolet blocking, and insulating values, to name a few of the available options.