The way window glass is divided into panes is often used as a sort of stylistic shorthand that determines what kind of windows a house gets. “Colonial” windows have removable dividers that architects like to call muntins and window suppliers call grilles. “Contemporary” windows have large, undivided panes. “Cottage” windows often have diamond muntin patterns, while “Arts and Crafts” windows have a racing stripe pattern, with muntins that follow the inside edge of the sash. These sorts of distinctions have their place, but they can mask the more utilitarian, nuts-and-bolts considerations that have an important bearing on the comfort and convenience of a home. Those considerations have to do with how windows operate, and despite the tremendous variety of windows we see
