Windows & Doors Glossary Terms

When you’re researching replacement windows and doors for your home, or when communicating with home improvement contractors, it can help to know some industry terms, such as these:


American Architectural Manufacturers Association. The association of manufacturers that sets the industry’s accepted standards for the production of doors and windows.

Argon Gas

The inert, nontoxic gas used for filling between glass panels as an insulator to slow heat transfer in energy-efficient windows.

Bay Window

A composition of three window units, usually with a large picture window in the middle and narrower windows on the sides. In a bay window design, the side windows are sometimes operable, often casement or double-hung styles.

Casement Window

A window hinged on both sides so that the sash can swing outward for full ventilation.


A sealing compound used for filling cracks and joints to prevent air and/or water leaks.


Condensation is the conversion of water vapor to liquid water, either due to the air cooling to its dew point or becoming saturated with water vapor to the point that it cannot hold more.

Double Hung Window

A window with upper and lower sashes in a frame in which the two panels slide past each other vertically and both can be tilted inward for convenient cleaning.

Dual Pane Window

A window made of two glass panes with an airspace between them.

Energy Star®

The EPA’s program for developing standard guidelines for energy efficiency of various manufactured products. The Energy Star designation is assigned to products such as windows, doors, kitchen appliances, and others that are assessed as meeting the program’s performance thresholds for energy-efficient windows, doors, and other products.

Krypton Gas

A clear, odorless, nontoxic gas frequently injected between triple panes of glass to maximize the effectiveness of energy-efficient windows by slowing the transfer of heat between the glass panes. Krypton gas is more effective but costs more than argon gas.


A company or a person that makes window products or one or more components that will become part(s) of a product for sale.

Non-hung Window

A window with a vertical sash that slides by use of slide bolts or mechanism so that the sash can be opened to one of its preset positions between completely open and completely closed.

Obscure Glass

Any glass that has been textured in some way, often by etching, frosting, or painting, to create privacy and still allow light into the room.

Operable Window

Any window type that can be opened and closed by sliding up and down, side to side, or inward and outward, vs. a picture window or other window types that are fixed in one position.

Picture Window

A stationary window that is designed to admit light and/or provide visibility of the exterior or interior space and that is not designed to open for ventilation.


A measure of a natural or manufactured insulating material’s capacity for resistance to heat flow. The higher the R-value, the greater the heat flow resistance, which means the better the insular quality of the material.


The vertical or horizontal stationary or sliding window panel. In double-hung windows both sashes open, instead of just one, for easier cleaning and better ventilation control.


A framed or frameless metal or plastic mesh covering for a window or door opening to prevent insects and blowing landscape debris from entering through the door while allowing normal airflow to enter the interior of the building.


A dense compound applied to fill crevices around windows and doors to block air from leaking into or out of the building.

Stress Crack

A crack in a panel of glass or other material due to excessive stress at a point along one of the edges.

Structural Test Pressure (STP)

The pressure applied in a test to determine if the requirements set for a window, door, or skylight design to withstand pressure are met.


A room with walls that consist largely of glass windows or doors and sometimes with a glass roof, designed to allow maximum sunlight into the room.

Single-Hung Window

A window with a stationary upper sash and a movable lower sash that can be raised up and down and tilted inward for convenient cleaning.

Sliding Glass Door

A double door unit in which the two framed glass panels can slide or roll past each other horizontally on parallel tracks within a single master frame. Often, one panel is stationary.

Thermal Expansion

An increase in the dimensions of any material caused by an increase or decrease in temperature, depending on the material type.


A measurement of a door’s or window’s rate of heat loss. A lower U-value means a greater level of heat flow resistance, which means a better insulation value.

Ultraviolet Light (UV)

A form of electromagnetic radiation with a shorter wavelength than visible light (but longer than X-rays). UV rays account for about 10% of the Sun’s total electromagnetic radiation.

Visible Transmittance (VT)

The percent of available light that enters through a window. A higher VT ratio means that more light is passing through the window.

Vertical Sliding Window

A window with one or more sashes in a single frame that slides vertically.

Vinyl Window

A window constructed from a Polyvinyl Chloride (PVC) material, either flexible or rigid, that is used in manufacturing energy-efficient vinyl windows and other building products.

Water Penetration

The extent of water infiltration as measured when a sample window is tested under specific conditions of air pressure differentials.


Any of the various insulating materials for covering the edges and joints between window sashes and the window frame or the door and frame to reduce air and/or moisture leaking.

Window & Door Manufacturers Association (WDMA)

The industry organization that establishes standards for the quality of windows, doors, and skylights, and provides various resources, education, and programs to help businesses provide increased value for customers.

Window Pane

A single glass panel in a window.

For More Information About Windows and Doors

Energy Shield engineers energy-efficient windows and doors specifically for high performance and long-term durability in the extreme conditions of the southwest U.S. desert region. We sell all our products factory-direct. That means our customers get the best possible price, quality, and service, expert factory-trained installers, and no third-party warranty handling.

Get information and a FREE BID for your new replacement windows anytime by calling Energy Shield Window & Door Company at (623) 936-3758, or fill out our online contact request.

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