Glossary
- Acrylic
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Thermoplastic glazing material.
- Aerogel
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A microporous, transparent silicate foam currently under development for potential use as a glazing cavity-fill material, offering very high thermal performance.
- Air infiltration
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The amount of air leaking in and out of a building through cracks in walls, windows and doors.
- Airspacer
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Component placed at the perimeter of an insulating glass unit to separate the two lites of glass.
- ANSI
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American National Standards Institute, a clearinghouse organization for all types of standards and product specifications.
- Tempered glass
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Glass heat-treated to withstand greater than normal forces on its surface. When it breaks, it shatters into small pieces to reduce hazard.
- Tenon
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A rectangular projection cut out of a piece of wood for insertion into a mortise.
- Thermal break
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A thermally insulating or low-conductance material used between interior and exterior aluminum (or other conductive material) window and door components.
- Tilt window
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A single- or double-hung window whose operable sash can be tilted into a room to allow cleaning of the exterior surface on the inside.
- Transom
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Window used over the top of a door or window, primarily for additional light and aesthetic value.
- Triple glazing
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Use of three panes of glass or plastic with two airspaces between. Generally refers to a sealed insulating unit.
- True divided lites (TDLs)
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Traditional window construction incorporating smaller panes of glass actually separated by muntins, rather than simulating such an appearance with larger lites of glass and a muntin grid or grille placed between or on the surfaces of the glass layers.
- U-factor
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Rate of heat flow-value through a building component, from room air to outside air. Also referred to as U-value. The lower the U-factor, the better the insulating value. U-factor, a rating more generally used in the window industry, is the reciprocal of R-value, a rating commonly used in the insulation industry.
- Ultraviolet light (UV)
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Invisible rays of solar radiation at the short-wavelength violet end of the spectrum. Ultraviolet rays can cause fading of paint finishes, carpets and fabrics, as well as deterioration of some materials.
- Vinyl
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Generic term for polyvinylchloride or PVC, an extruded material used for window and door framing.
- Warm-edge
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A type of insulating glass construction using an airspacer offering lower thermal conductance than traditional aluminum spacer. Warm-edge IG units typically offer higher resistance to condensation and an incremental improvement in window energy performance.
- WDMA
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Window and Door Manufacturers Association. Formerly the National Wood Window and Door Association, this trade organization has established many standards related to wood window and door products.
- Weatherstripping
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A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.
- Weld
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A term used for a type of corner construction, used with vinyl and other types of windows and doors, in which a small amount of material at the two pieces are melted or softened, then pushed together to form a single piece. This also is referred to commonly as a fusion-weld.
- Wildland/urban interface
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An area where buildings are bounded by wild or natural areas in regions where wild fires are a concern. Some fire and code officials are looking at the establishment of fire-resistance requirements for exterior building products in these "interface" areas.
- Wind load
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Force exerted on a surface by moving air.
