Argon Gas: injected between layers of glass to increase the insulation value of the window. Argon gas has no smell or color, and is heavier than oxygen.
Awning Window: similar to a casement window, but the window opens at the bottom by turning a hand-held crank.
Balance: the mechanism that holds up sash units on single and double hung windows. It also helps control the force needed to raise and lower sash.
Bay Window: a three-sided window that is three-dimensional, protruding from the house.
Bow Window: a curved window created by smaller windows mulled together.
Casement Window: window that opens from one side, like a door, by turning a hand-held crank.
Casing: decorative trim around interior frame of window.
Compression Jambs: liner in window jamb that can be pushed in, allowing you to tilt the window sash. Assists in maintaining weather-tight seal between window sash and jamb.
Cottage Style Window: on a double-hung window, the bottom sash is larger than the top sash.
CPVC: cellular polyvinyl chloride. A composite material more rot resistant than wood.
Crank Handle: opening mechanism for the casement and awning window.
Double Hung Window: a window in which both the top and bottom sash move up and down.
Egress: the size opening a window creates for access.
Fixed/Picture Window: a window with no moving parts or sashes.
Grilles/Muntins: decorative window dividers installed on the exterior or interior of the window or sandwiched between the glass (see GBG). Offered in variable widths.
Grilles-Between-The-Glass (GBG): grilles inserted between two pieces of glass, making the window pane easier to clean.
Head: the horizontal member forming the top of the window frame.
Jamb: vertical members of the window frame.
Jambliner: internal frame part that holds the sash in place.
Keeper: on a doublehung window, this is part of the lock system that engages the lock latch for a secure fit.
Low-E: stands for "low emissivity". Low-E coating on a window pane lets light in, yet reflects heat and keeps harmful UV rays out in the summer and keeps heat inside during the winter.
Mulled: the way windows are attached together to create a combination.
Nailing Flange/Fin: piece extended from the window frame to make installation easier. Premium windows will offer an integral nailing fin for more secure installation, with predrilled holes for easy nailing.
NFRC Rating: National Fenestration Rating Council (NFRC) provides unbiased energy performance ratings for windows, doors and skylights. Independent NFRC ratings provide the basis for the Energy Star's® window performance requirements.
Rail: horizontal part of a sash.
Rough Opening: framed opening in wall in which a window is installed.
R-Value: marks a window's resistance to heat loss or gain. The higher the R-value, the better the window reduces heating and cooling bills.
Sill: the horizontal piece forming the bottom of the window frame.
Simulated True Divided Lites (STDL): grilles attached to the interior and exterior of a window, with a bar between the window panes, to give the appearance of true divided lites.
Single Hung Window: a window with only one sash-usually the lower one-that moves up and down.
Spacer: material along the perimeter of the sash, sandwiched between two pieces of glass.
Stile: vertical part of a sash.
Tempered Glass: type of glass that, when broken, shatters into small pieces to protect you from injury.
Thermal Break: part of a window or door that reduces transfer of cold or heat from one surface to another.
Tilt Latch: a locking mechanism that, when released, enables the sash to tilt inward.
Tilt Pins: on a tilt double-hung window, tilt pins rotate the sash when it opens into the home.
True Divided Lites: muntins in a cross-hatch pattern creating one window with several small separate windows within.
UV (Ultraviolet) Rays: the rays of the sun that can filter through windows and heat up a room, as well as fade furniture, rugs, etc.
U-Value: the amount of heat entering or escaping through a window. The lower the U-value, the better the insulation value.