Some Common Retrofit Double Glazing Terms & Expressions
Air Space The space in the cavity between two panes of glass in an insulated glass unit.
Argon Gas An odorless, colorless, tasteless, non-toxic gas which is six times more dense than air. It is used to replace air between the glass panes to reduce temperature transfer.
AS3959 Australian Standard covering “Construction of buildings in bushfire-prone areas.“ Incorporates Bushfire Alert Level Ratings (BAL)
Awning Window A top-hinged window that swings outward for ventilation.
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.
Condensation The accumulation of water vapors 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.
Desiccant. An extremely porous crystalline substance used to absorb moisture from within the sealed air space of an insulating glass unit, preventing condensation within the IGU.
Double Hung Window A window that has two operable sash which slide vertically.
Extrusion. The process of producing uPVC or aluminum shapes by forcing heated material through an orifice in a die.
Frame. The fixed frame of a window which holds the sash or casement as well as hardware.
Glazing The 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 to the plastic interlayer-preventing glass fallout in the home.
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.
Patio Door A glass door that slides open and close on adjustable tandem rollers. Available in 2- or 3-lite configurations with the operable panel available in any position.
Retrofit Double Glazing Fitting new Insulated Glass Unit (IGU) to existing frames
Sash The part of the window which contains the glass.
Secondary Glazing Adding an extra panel of glass or acrylic to existing windows.
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.
Ultraviolet light (UV). The invisible rays of the spectrum that are outside of the visible spectrum at its short-wavelength violet end. Ultraviolet rays are found in everyday sunlight and can cause fading of paint finishes, carpets, and fabrics.
U-value Amount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality.
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.
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.
WERS Australia’s Window Energy Rating Scheme.