Egress window: Is a window large enough that is required in specific locations in a dwelling and is intended to provide an emergency exit.  Windows must meet specific building codes, size and requirements

E-Value: the reflective value of a window to help prevent heat from escaping and reflect long-waveheat energy, the lower the value, the better the insulating quality of the material.

Extension Jambs: Flat parts made of wood, or other materials which are attached to the inside edges of a window to fill the space between the window and the interior molding.

Eyebrow windows:  is rectangular on the bottom and slightly arched on the top.

Energy Rating Energy performance as affected by the energy efficiency of the framing, weatherstrip, and window glazing. Set by the National Fenestration Rating Council.

ENERGY STAR Certification Program An Environmental Agency (EPA) and Department of Energy (DOE) certification program for NFRC windows that are 30% or more energy efficient above Model Energy Code standards.

Extrusion: The process of forcing heated materials such as aluminum or vinyl through a die to produce specified shapes.