Electrochromics. Glazing with optical properties that can be varied continuously from clear to dark with a low-voltage signal. Ions are reversibly injected or removed from an electrochromic material, causing the optical density to change.
Electromagnetic spectrum. Radiant energy over a broad range of wavelengths.
Emergency exit window. Fire escape window (egress window) large enough for a person to climb out. In U.S. building codes, each bedroom must be provided with an exit window. The exact width, area, and height from the floor are specified in the building codes.
Emittance. The ratio of the radiant flux emitted by a specimen to that emitted by a blackbody at the same temperature and under the same conditions.
Evacuated glazing. Insulating glazing composed of two glass layers, hermetically sealed at the edges, with a vacuum between to eliminate convection and conduction. A spacer system is needed to keep the panes from touching.
Exterior stop. The removable glazing bead that holds the glass or panel in place when it is on the exterior side of the light or panel, in contrast to an interior stop located on the interior side of the glass.
Extrusion. The process of producing vinyl or aluminum shapes by forcing heated material through an orifice in a die. Also, any item made by this process.
Eyebrow windows. Low, inward-opening windows with a bottom-hinged sash. These attic windows built into the top molding of the house are sometimes called "lie-on-your-stomach" or "slave" windows. Often found on Greek Revival and Italianate houses.