Glossary

Learn the lingo of windows and doors with this A-Taylor Made Window glossary of terms.

AAMA: the American Architectural Manufacturers Association, which establishes product quality and performance standards, and conducts product certification program and installation training programs.

air infiltration: the amount of unwanted air that escapes between a window sash and the frame, measured by volume — cubic feet of air per minute, per square foot of area. A window frame with a low-number air infiltration rating is more airtight than one with a higher number.

aluminum-clad window: a window that has a weather-resistant aluminum covering over the exterior portions of its wooden framing.

argon: an odorless, colorless, nontoxic, nonflammable inert gas that is injected between the panes of glass in many insulated low-E glass windows to reduce temperature transfer.

casing: molding or framing that covers any space between a window or door and the surrounding structural support.

conduction: transfer of heat or cold from one surface to another by means of direct contact.

convection: transfer of heat through the air, by means of currents that flow from a warm surface and envelop a nearby cooler material.

damage function: the combined percentage of solar ultraviolet and visible light that can contribute to fading of upholstery and carpeting. Windows with a low damage function number help reduce fabric fading.

egress window: an emergency access window with a specified minimum size large enough for a firefighter or other emergency responder to climb through or a resident to climb out during an emergency. Federal building codes require an egress window in each bedroom of a home.

glazing: glass panes that compose a window.

grilles: patterns of decorative trim strips that visually divides large panes into a grid of smaller sections, creating the impression of a traditional design. Grilles can be rectangular, square or diamond-shaped.

heat gain: indoor temperature increase through windows, doors, walls and roofing, attributable to exposure to direct sunlight. Conversely, heat or energy loss is “leakage” of interior heated or cooled air to the outside.

krypton: an odorless, colorless, nontoxic, nonflammable inert gas that , like argon, is injected between the panes of glass in some low-E glass windows to reduce temperature transfer. In comparison to argon, krypton is denser and yields higher insulation performance, but because of its relative rarity is more expensive. Because krypton gas is more suitable to thinner spaces, it is most appropriate for triple-pane windows.

laminated glass: a type of glazing in which two sheets of glass are attached by adhesive to a center layer of transparent plastic to improve the resistance of a window to shattering.

low-E coating: a thin metallic coating that reflects heat and ultraviolet rays. Over time ultraviolet radiation can harm textiles, wallpaper and flooring. Applied to the exterior of a window, a low-emissivity or “low-E” coasting (also called a spectrally selective coating) can deflect the sun’s heating rays. Applied to the interior surface of a window, a low-E coating can help retain your home’s warmed air during cooler months.

mullion: a joint that attaches two or more windows or doors to each other.

muntins: rods or strips that are used to create the impression that a pane of glass is divided into smaller sections. Also called grilles, grids or dividers.

National Fenestration Rating Council (NFRC): a nonprofit organization that measures and certifies the energy performance of windows, doors and skylights. Fenestration is the arrangement of a building’s exterior doors and windows in proportion to walls.

obscure glass: Windows with a texture or coating that makes them opaque to varying degrees — translucent, but not transparent, for privacy.

outdoor/indoor transmission class (OITC): a method of measuring the degree to which windows muffle sounds originating outdoors.

R-value: a calculation of the ability of substances to resist heat transfer. A high R-value indicates good insulation qualities. R-value is primarily used to rate wall and ceiling insulation values, but the calculation is not well-suited to windows or doors, for which U-value is a more comprehensive measurement.

sidelight: a tall, narrow glass insert mounted alongside a door or window.

solar heat gain coefficient (SHGC): measurement of the amount of heat from the sun that a window transfers indoors rather than deflecting it. Solar heat gain through windows and window frames places additional load on air conditioning systems and contributes to additional energy costs; solar heat gain can be desirable in cold climates, however, to enhance home heating. SHGC is expressed as a decimal number between 0 and 1; a low SHGC number (such as 0.35 or lower) indicates high suppression of solar heat gain. Type of glazing, number of panes, glass coatings and frame composition all influence SHGC ratings.

STC (Sound Control): the measurement of a window’s ability to dampen sounds from outdoor sources. A higher number indicates better sound suppression. Single-pane windows typically have an STC rating of about 26, while double-pane windows usually have an STC of 30 or higher. A 6-point increase in STC equates to a 50 percent increase in noise suppression. Sound reduction is independent of insulation; that is, insulation components do not necessarily dampen sound, or vice-versa.

thermal break: a component inserted into a window frame to reduce heat transfer.

transom: a window mounted over a door or another window.

ultraviolet (UV) light: invisible damaging radiation with a wavelength shorter than the violet end of the electromagnetic spectrum. Ultraviolet rays can cause fabrics, carpeting, upholstery, painted and other colored materials to fade and otherwise deteriorate. Various window coatings and configurations help deflect UV light to reduce the amount of it that enters your home.

U-value: an overall rating of a window’s insulation capabilities, based on a calculation of numerous variables. Material, engineering and manufacturing quality, window style, glass pane spacing and insulation elements, gas injected between panes, and glass surface treatments all influence heat transfer and, therefore, insulation quality. Low U-values (also called U-factors) indicate superior insulation properties. U-value must be .32 or lower to meet Title 24 requirements for the Bay Area.

wood-clad window: a window consisting of a wood-frame visible from the interior with a protective coating of vinyl, aluminum or fiberglass on the exterior side.

weep: a hole or channel in a window frame that drains condensation and rain water to the exterior.

Our experts will gladly tell you all you want to know about materials, configurations, durability, energy-saving characteristics and installation of windows and doors. This online resource section is a good place to start.

• Find many answers in our list of frequently asked questions
• Acquaint yourself with government energy-savings standards and codes