Australian Glass and Window Association


Australian Building Codes Board


Sound and its control - Rw used as the common indicator of how much decibels (dB) is blocked by the glass


Australian Fenestration Rating Council - the NCC regulated protocols and procedures of how we calculate Total System values (e.g. U-Valuew, SHGCw) and administers the independent WERS rating and labelling system


Australian Glass Group

Air gap

The trapped and protected air gap in an IGU - commonly filled with Argon gas for further Insulation performance

Air Infiltration (AI)

How much air can get through a Total System - as per physical tests from an AS 2047 test. The lower the number the less air, moisture, heat and noise passes through

Annealed Glass

Standard glass before any further heat treating (toughening or heat strengthening)

Argon gas

An inert gas used commonly in the air gaps of IGU units to add further Insulation properties (lower U-Value)


Like sanding the edges of glass so it is safe to handle with no sharp points



Building Code of Australia that are in the NCC

Butt Joint

Where glass on glass is glazed together without a frame, using a silicon sealant.


Carbon Dioxide

The most common offending Greenhouse gas linked to Global Warming

Carbon Footprint

The total amount of greenhouse gases generated by an individual building

Carbon Neutral

Heating and Cooling our buildings without releasing CO2-e gasses


Carbon Dioxide


Carbon Dioxide and equivalents (ie. all Green House Gases)

Coated Glass

A coating applied to one of the glass surfaces - commonly LowE coating (Hardcoat or Softcoat)


Glass colour. Standard common float glass is labelled as "Clear"


Where relative humidity and colder temperature meet at the 'Dew point' and water droplets form. Usually seen on the inside of regular glass and aluminium during very cold mornings.


Heat transfer from "hot to not" through objects that are touching


Heat transfer from “hot to not” through a fluid (like air or water)

Corner joint

Where glass on glass is glazed together at a corner without a frame, using a silicon sealant. Here stepped units can be used.

Curtain Wall

Non-load bearing glazing seen in Commercial buildings.


Chemical Vapour Deposition - the Hardcoat LowE manufacturing process



Bending that can occur in glass under pressure eg wind load and altitude changes


Small beads used in some spacer bars of an IGU to help absorb moisture


Double Glazed Unit (2x pieces of glass and 1x air gap)


Embodied Carbon

The past carbon footprint that lead to the construction of a building including how the materials are manufactured and delivered


European Standards - the European standards that govern how glass and Total Systems are calculate in Europe - be aware that you must translate such values in to AFRC standards to be used in Australia

Energy Efficiency

Using less Energy for the same result (ie. the Heating and Cooling of our buildings)



The Diehodler material used to house the glass eg. Aluminium, Thermally Broken Aluminium, Steel, Timber, uPVC or composites using multiple materials



Float Glass aka Float, Clear, Clear Glass, Annealed, Annealed Glass. Can be clear, tinted, patterned, acid etched, coated, laminated

Glass Surface

The sides of a piece of glass. Single glazed glass as 2x surfaces: surface #1 is always outside exposed to the elements while surface #2 will be inside the building and you can touch that surface from inside

Grade A Safety Glass

Either Toughened or Laminated glass certified to AS 2208



Pyrolytic Coated LowE - uses Indium Tin Oxide as the primary metal and comes with risk of haze appearance

Heat Soak

A process conducted on Toughened glass in a Heat Soak chamber to test for inclusions like Nickel Sulphide. Passing this test offers piece of mind of a very low risk of Spontaneous Combustion

Heat Strengthening

Heated and Cooled in a furnace to be up to 2x stronger than standard annealed glass but not Grade A Safety glass like Toughened glass is

Heat Treating

Further processes to glass - Heat Strengthening, Toughening and Heat Soaking



Insulated Glass Unit (most commonly a Double Glazed Unit or Triple Glazed Unit)


How well the glazing retains heat inside - measured by the U-Value



2x or more glass panes glued together with an interlayer (normally clear) and Grade A Safety glass

LowE / Low E / Low-E

Low Emissivity coated glass - low non-solar heat transfer through the glass

LSG ratio

Light to Solar Gain ratio - VLT divided by SHGC - anything over 1.25 is considered to be spectrally selective and anything over 2.0 is very high performing as it offers twice the amount of light entering inside versus heat



National Construction Code


National Energy Productivity Plan


A subtle Tone, not Clear and not an obvious Tinted Colour either


National Fenestration Rating Council - the North American standards that the AFRC is derived from


National Federation Reform Council. The new name since 2020 for the Council of Australian Governments (COAG)

Nominal Thickness

The key identifiable thickness of glass. In reality there is always a tolerance of exact mm


Paris Agreement

Global agreement on countries CO2-e emission reductions by the year 2030

Passiv Haus

See Passive House

Passive House

A German based building modelling standard for energy efficient buildings


Psi Value (pronounced "sigh") - similar to U-Value but by thickness - how much non-solar heat passes through the glass by Watts per thickness (mm)


Physical Vapour Deposition - the Softcoat LowE manufacturing process



An average Weighted Sound Reduction Index of decibels (dB) across a full range of Hertz frequencies - how much dB is blocked from common noise offenders, the higher the value the more noise is blocked



A factor looking at the comparison of sun-heat blocking ability (lower SHGC) compared to how much natural sun-light can transmit through the glass (VLT). The concern being you achieve the required lower SHGC but the glass is very dark with low levels of natural light entering inside. This utilises the LSG ratio of VLT/SHGC and a ratio of 2.0 or more is desirable for Commercial buildings. To be Spectrally Selective, a glazing requires at least a 1.25 LSG ratio


Solar Heat Gain Coefficient - Solar Control - how much heat from the sun enters through the glass inside the building. The lower the number the more heat from the sun is blocked form entering inside through the glazing eg. 0.73 = 73% sun heat enters inside / 0.27 = 27% sun heat enters inside


Total System SHGC (glass + frame + sealants)


Sputter Coated LowE - uses Silver (Ag) as the primary metal

Solar Control

How well the glazing either allows heat from the sun to pass through the glazing to the inside of the building (desirable for colder climates) or blocks (desirable for warmer climates)

Spontaneous Combustion

The explosion of Toughened glass due to inclusions like Nickel Sulphide. This could be hours, days, weeks or even years later

Stepped unit

Where a DGU will have one side of the unit step past the finished spacer bar sealant of the other side





Triple Glazed Unit (3x pieces of glass and 2x air gaps)

Thermal Stress

The cracking of Annealed glass due to extreme temperature differences in the one piece of glass


Tinted float glass - aka body tinted. Common colours are Grey and Green. Also available as Bronze, Blue, Dark Grey


Neither Clear or a Tinted Colour but subtle tone - eg. Neutral


Heated and Cooled in a furnace to be up to 5x stronger than standard annealed glass and Grade A Safety glass - aka Tempered



Frame-Only U-Value


Glass-Only U-Value


Ultraviolet light, not be get confused with U-Value (UV = harmful fading factors that can pass through glass and fade carpets, timber floors, furniture and artwork)


Thermodynamic symbol for heat transfer - Insulation - how much non-solar heat passes through the glass by Watts per m2. The lower the number the less heat loss / the better the Insulation


Total System U-Value (glass + frame + sealants)



Visible Light Reflection - Inside (how much light is reflected from the inside - in)


Visible Light Reflection - Outside (how much light is reflected from the outside - out)


Visible Light Transmittance (how much % of sun light enters inside a building)

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