Most home weatherizing projects involve windows because they are largely responsible for the loss of home thermal energy. What makes windows energy-efficient is their ability to block air movement, creating dead air space between the inside and outside glass panes. Most windows today come with double or triple-pane insulated glass. Basically, insulated glass is two or three pieces of glass separated by a spacer bar and sealed on all four sides to create a dead air space between the panes. You can easily make single-pane, older windows more energy-efficient by creating dead air spaces using window weather-stripping materials, a good…