Annealed glass
Normal float glass. A slow cooling process during its manufacture (annealing) releases the internal tensions within the glass to allow cutting and processing.
Bevelling
Grinding process on the perimeter surface of the glass for a variable width of 10~30 mm.
Bonded Structural Glazing (VEC)
System for fixing glass to a supporting structure by means of a structural silicon.
Chemically-tempered glass
Float glass, the surface of which has been chemically strengthened by ion exchange at high temperature to give a very high mechanical resistance. This is a high technology product.
Colour rendering (Ra)
Indicates the percentage of colour fidelity as seen through the glass. The maximum is Ra = 100.
Curtain walls
Term that indicates the construction of an aluminium/glass structure as cladding of a building.
Curved glass
Annealed glass curved by heating to its softening point.
ET (Direct Energy Transfer)
Indicates the percentage of solar radiation that glass allows through. Fraction of solar irradiance that is directly transferred through the glass without altering the length of the wave.
E, EI, EW
Symbols, associated with a time in minutes (30-60-90-120) that define the fire resistance classes.
E: Break criterion of flames and hot gases.
I: Thermal insulation criterion of the protected side during the fire (<140° C average: <180° C local).
W: Optional criterion of limiting the maximum heat transmission (15W/m² at a distance of 1 metre).
I: Thermal insulation criterion of the protected side during the fire (<140° C average: <180° C local).
W: Optional criterion of limiting the maximum heat transmission (15W/m² at a distance of 1 metre).
Emissivity
Emissivity is a surface property. When there are two surfaces at different temperatures, they exchange heat by radiation depending on the emissivity. The normal emissivity of standard glass is 0.837 (UNI 10345), that of low emissivity glass (Low-E) can be significantly lower than 0.20.
Enamelled glass
Glass in which one of the two faces is enamelled and then tempered.
Energy absorption
Percentage of energy absorbed by the glass that causes heating. This value determines the risk of damage by thermal shock.
Energy balance (K balance)
The difference between the thermal load and loss through the glass and windows.
Energy transmission (Te)
Energy percentage, emitted by the solar radiation, which crosses the glass.
EVA (ethylene vinyl acetate)
A film that ensures, through a technological process, the mechanical assembly of glass components in laminated products.
Fire stop
Term that refers to products that meet fire resistance criteria (REI-EI).
Float
This is a type of glass obtained from a production process in which the glass floats on a bath of molten tin. This is the most widespread productive technology in the world.
Float glass
See float-glass.
FS (Solar factor or total energetic transmission)
This is the ratio between the amount of total light of solar energy that glass lets through (light + radiation + transmitted energy by convection due to the heating of the sheet through absorption) and the total amount of solar energy arriving on the glass (light + radiation).
The solar factor of a window is the ratio of the total energetic flux that enters the room through the glass and the incoming energetic sun flux.
This total energy is the sum of the incoming solar energy through direct energy transfer (DET) and energy released by the glass to the indoor environment after its heating through energy absorption (EA).
Grinding
Process to glean the corners of the sheet and avoid a sharp edge.
Heat Soak Test (HST/THS)
Treatment following the quenching, intended to dramatically reduce the risk of spontaneous breakage of the hardened sheets.
Heat tempered glass
Glass which has undergone a reinforcing heat treatment that increases its mechanical resistance or its resistance to thermal shock without altering the light or energy properties of the base product. Its fine fragmentation make it a safety product in most applications.
K-Coefficient
Coefficient which in the past identified the U-Coefficient – Heat transmission rate.
Kiln-formed glass
Moulded product from molten glass.
Lacquering
Cold application of polyurethane lacquer on a glass surface. Technology evolved over time with ecological industrial lacquers such as Lacobel by AGC.
Laminated
This glass is comprised of two or more sheets internally coupled by a clear or coloured film (PVB or resin).
Laminated
This glass is comprised of two or more sheets internally coupled by a clear or coloured film (PVB or resin).
Light transmission (LT)
Indicates the percentage of sunlight that glass lets through. Luminous flux transmitted through the window in relation to the incident luminous flux according to the CIE D65 standard curve with spectral density from 380 nm. To 780 nm.
Low-E
Name in English given to low emissivity glass (see low emissivity).
Low-emittance
Annealed float glass made reflective to long wavelength infrared by depositing semiconductor metals or metal salts through pyrolysis or sputter.
Luminous transmission (Tl)
Percentage of visible light emitted from the solar radiation that passing through the glass.
Optical reflectance
Indicates the percentage of sunlight that glass reflects outwards. Luminous flux reflected from the glass in relation to the incident luminous flux according to the CIE D65 standard curve.
Point-fixed structural glazing (VEA)
System for fixing glass to a supporting structure by means of a special point-fixing system.
Pressed
Cast and laminated glass with both faces stamped with ornamental designs.
Pressed glass
Translucent flat-glass obtained by rolling between two cylinders that imprint a relief pattern on one or both sides.
PVB (polyvinyl butyral)
A plastic film that ensures, through a technological process, the mechanical assembly of glass components in laminated products.
RE (energy reflectivity)
Indicates the percentage of solar radiation that glass reflects outwards. Fraction of solar irradiance that is reflected from the glass.
RE, REI, REW
Symbols, associated with a time in minutes (30-60-90-120) that define the of fire resistance class.
RE: Break criterion of flames and hot gases.
I: Thermal insulation criterion during the fire.
W: Optional criterion of limiting the maximum heat transmission.
RE: Break criterion of flames and hot gases.
I: Thermal insulation criterion during the fire.
W: Optional criterion of limiting the maximum heat transmission.
Reinforced
Glass in which reinforcing wires have been inserted, usually square mesh.
Reinforced Thermal Insulation
An insulated window is known as Reinforced Thermal Insulation when it is composed of a low emissivity glass.
Rotool
Screw system for curtain walls
Sandblasting
Procedure which, through the action of the sand sprayed at high pressure, a opaque effect is obtained on all or part of the sheet’s surface.
SC (Shading Coefficient)
The shading coefficient is the ratio between the solar factor of the relevant glass and solar factor of a 3 mm thick sheet of clear glass. The shading coefficient is the ratio between the solar factor of the window taken into consideration and the solar factor of a 3 mm sheet of clear glass, the value of which is 0.87.
Shading Coefficient
The shading coefficient for 3 mm thick clear glass is 1. The shading coefficient of a product is obtained by dividing its solar factor by 0.87. The shading coefficient for 3 mm thick clear glass is 1. The shading coefficient of a product is obtained by dividing its solar factor by 0.87.
Silk finishing
Chemical process by which, with the action of hydrofluoric acid, a translucent effect of the sheet surface is obtained.
Silk screening
Method for decorating or writing with inks, varnishes and paints on sheets of glass.
Silvering
Surface treatment that renders a sheet of glass reflective by applying metallic silver on one of the surfaces, by means of precipitation from silver nitrate. In current usage, such as mirrors, protection from chemical and mechanical agents is achieved by painting or plastic covering.
Sound absorption (RW)
Index that characterizes the acoustic qualities of a wall or glass. It indicates the difference in sound levels that are recorded from both sides of the wall or glass for a given noise spectrum (e.g. road noise).
Structural facade
Term indicating a facade in which only the windows are visible, sustained internally by supports.
Tempering
Heat treatment that significantly increases the mechanical strength and thermal shock, as well as safety.
Thermal shock
Thermal shock is the fracture of a sheet due to partial heating by strong sunlight, or when a shadow (building, tree, etc..) has obscured, rapidly and in part, a heated sheet, thereby creating a temperature differential on the sheet itself.
Toughened glass (or semi-tempered)
Glass that has undergone a semi-tempering heat treatment which increases its strength and its resistance to thermal shock. Cannot be regarded as a safety product.
U (Heat transmission)
Identified as K-coefficient in the past.
The U-coefficient identifies the thermal insulation level of the glass (heat transmission that passes through a 1 square meter area between the two environments has a temperature difference of 1 degree (expressed in W/m²K).
The lower the heat transmission value, the higher the insulating capacity of the glass.
The U-coefficient identifies the thermal insulation level of the glass (heat transmission that passes through a 1 square meter area between the two environments has a temperature difference of 1 degree (expressed in W/m²K).
The lower the heat transmission value, the higher the insulating capacity of the glass.
U-coefficient (K-coefficient in the past)
See U – Heat transmission rate.
Ultraviolet transmission (TUV)
Fraction of ultraviolet radiation (spectral field between 280 and 380 nm).
UV Transmittance
Percentage of UV light emitted from the solar radiation that passing through the glass.
Warm-edge
Term specifying a "warm edge effect" created by the spacer in the insulating glass having a low thermal conductivity.