Glossary of Double Glazing Common Terms

Acoustic Insulation Acoustic insulation, such as double glazing, is used to reduce the nuisance caused by outside noise. Acoustic insulation works by reducing a sound wave’s energy.

Air SpaceThe space in the cavity between two panes of glass in an insulated glass unit.

Argon Gas An odourless, colourless, tasteless, non-toxic gas which is six times denser than air. It is used to replace air between the glass panes to reduce temperature transfer.

AS 3959 Australian Standard covering“Construction of buildings in bushfire-prone areas.“IncorporatesBushfire Alert Levels (BAL)

AWA Australian Window Association.

Awning WindowA top-hinged window that swings outward for ventilation.

BAL Bushfire Alert Levels. See AS 3959 above.

Bay Window An angled combination of three windows that project out from the wall of the home. The windows are commonly joined at 30- or 45-degree angles.

Casement Window A window with a side-hinged sash that opens outward for ventilation.

Clerestory. A window near the top of an outside wall.

Condensation The accumulation of water vapours or droplets as the result of warm, moist air coming in contact with a cold surface and cooling to its dew point temperature. Condensation may occur when a cold window glass or frame is exposed to humid indoor air. Low-conductivity, insulated glass and warm-edge spacers reduce condensation. Read more about condensation.

Dormer A space which protrudes from the roof, usually including one or more windows.

Double Glazing Glazing that incorporates two panels, separated with an air space, for the purpose of thermal and acoustic insulation.

Double Hung Window A window that has two operable sash which slide vertically.

Fenestration An architectural term referring to the arrangement of windows in a wall.

Frame That part of a window assembly surrounding the sashes or fixed glazing.

French Door A particular design of swing door, all or a large part consisting of divided glass panes.

Gasket A pliable, flexible continuous strip of material used to affect a watertight seal between a sash and frame much like the seal around a refrigerator door.

GlazingThe process of sealing the glass to the sash.

I.G. Unit (Insulating Glass Unit) Two or more plates of glass separated by a spacer and hermetically sealed at the glass edges.

Jamb Vertical sections of the main frame.

Laminated Glass Specially designed glass where two panes of glass are bonded to a durable interlayer, providing increased safety, UV protection and noise reduction. If the window or door gets broken the glass will adhere to the plastic interlayer-preventing glass fallout in the home.

Lintel A horizontal framing member placed across the top of the rough opening of a window or door opening to prevent the weight of the wall or roof from resting on the window frame.

Low E (Emissivity) Glass Glass with a transparent metallic oxide coating applied onto or into a glass surface. The coating allows short-wave energy to pass through but reflects long-wave infrared energy which improves the U-value.

Main Frame The head, sill and jambs sections of a window.

Mullion A vertical or horizontal connecting unit between two or more windows.

Obscure Glass Glass that has been made translucent instead of transparent.

Pane A sheet of glass for glazing a window.

Patio Door A glass door that slides open and closes on adjustable tandem rollers. Available in 2- or 3-lite configurations with the operable panel available in any position.

Safety Glass A strengthened or reinforced glass that is less subject to breakage or splintering, such as glass for storm doors and some windows.

Sash The opening part of the window.

Sill The horizontal, bottom section of the main frame.

Single Hung Window A window in which one sash slides vertically and the other sash is fixed.

Single-strength Glass Glass with a thickness of approximately 3/32?.

Slider Window A window in which the sash move horizontally. Sliders are available in a 2- or 3-lite configuration, with the 3-lite having operable end vents.

Sloped Sill The sill of the window that has a downward slope to the outside. This sill has sufficient degree of slope to aid in water runoff.

Solar Heat Gain Coefficient (SHGC) The percentage of heat gained from both direct sunlight and absorbed heat. The smaller the number, the greater the ability to reduce solar heat gain.

Spacer Material placed between two or more pieces of glass in order to maintain a uniform width between the glass, and prevent sealant distortion.

Tempered Glass Glass with a surface compression of not less than 10,000 psi, or an edge compression of not less than 9,700 psi. When broken, the glass breaks into pebbles instead of shards.

Tilt & Turn Windows Windows with fittings that make it possible to rotate the window through 180º so that the exterior pane is facing inwards. This is very practical when washing windows.

Triple Glazing Glazing that incorporates three panes of glass, enclosing two separate air spaces.

uPVCWA UPVC Window Alliance

U-valueAmount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality.

VCA Vinyl Council of Australia

Visible Light Transmittance The percentage of light that is transmitted through glass in the visible light spectrum (380 to 720 nanometers). The higher the number the higher the percentage of visible light transmitted through the window.

Weather Seal sash glazed with three lights of glass, enclosing two separate air spaces.

Weep Slots Slots or holes in the sill (bottom) member of the sash frame that allows water to escape. Weep flaps add a vinyl flap to keep insects out.