The science of sound and sound control.

In reference to float glass, the side that was up or exposed to the "air" when it was manufactured. The bottom side is referred to as the "tin" side because it floated on a liquid tin bath. Coatings are applied to the air side.

An aluminum or stainless steel frame (desiccant filled) used to separate two lites of glass in an insulating unit.

Raw glass with low, residual stresses. This enables cutting and fabrication.

An invisible, non toxic gas used in insulating units to enhance the units insulating performance (u-value).

A vessel that employs high pressure and heat. In the glass industry, used to produce a bond between glass and PVB or urethane sheets, thus creating a laminated glass product.

The dimension by which the framing system overlaps the edge of the glazing infill.

A laminated glazing construction commonly specified to mitigate injuries from flying glass resulting from an air-blast explosive.

A multiple lamination of glass or glass and plastic that is designed to resist penetration from medium-to-super-power small arms and high-power rifles.

The installation of glass products where the vertical glass edges are without structural supporting mullions.

Shortened term for polyisobutylene. The primary seal of an insulating unit and key component in restricting moisture vapor transmission.

A small tube factory-placed into the air spacer of an insulating unit used for balancing interior and exterior pressures during transportation over higher elevations, i.e. mountain ranges or air transport.

A ceramic frit enamel applied to glass for decorative/aesthetic appearances. Applied with a large roller for full coverage applications or through a screen for silkscreening applications.

A general reference to any glass incorporting a reflective or low-e coating.

The appearance of moisture (water vapor) on the surface of an object caused by warm moist air coming into contact with a colder object.

A framing system that captures the glazing component in the glazing channel.

An unbonded area in laminated glass between glass and PVB.

Small, extremely porous beads used to absorb moisture in the sealed air spacer of an insulating unit.

General areas of optical deviation or image deformation as seen looking at the glass.

An insulating glass unit in which both the interior and exterior components are a laminated glass.

Refers to clear 1/8" (3mm) thick float glass.

Refers to an insulating unit with a primary seal of polyisobutylene (butyl) and a secondary seal of silicone.

The measure of a surface's ability to emit long-wave infrared radiation.

To alter the surface of glass with hydrofluoric acid or other caustic agents. Permanent etching of glass may occur from alkali and other runoff from surrounding building materials.

Based on ISO-DP10292 draft standard conditions. It is based on an outdoor temperature of 5.5°C, and indoor temperature of 20.5°C and a 4.8 m/s outdoor air velocity

Raw glass, float refers to the process in which the glass was made.

Glass that has been heat-treated to have either a minimum surface compression of 10,000 psi or an edge compression not less than 9,700 psi in accordance with the requirements of ASTM C 1048, kind FT or meet the requirements of ANSI Z97.1 or CPSC 16 CFR 1201 safety glazing standards. Tempered glass is 4-5 times stronger than annealed glass, and when broken, breaks into small, relatively harmless, pieces.

One or more lites of flat glass bonded with an aliphatic urethane interlayer to one or more sheets of extruded polycarbonate in a pressure/temperatuer/vacuum laminating process.

(n) A generic term used to describe an infill material such as glass. (v) The process of installing an infill material into a prepared opening in windows, door panels, partitions, etc.

A special fabrication done to the edge of a piece of glass. Makes the edge smooth and gives it a whitish/gray appearance.

A process of heating glass to a specific temperature for a specified time in a special oven in an attempt to find any impurities in the glass known as "nickel sulfide inclusions".

Glass that has been heat-treated to have a surface compression between 3,500 and 7,500 psi and meet the requrements for ASTM C 1048, kind HS. It is ~2-3 times the strength of annealed glass. Heat-strengthened glass is not a safety glazing material and will not meet the requrirements of ANSI Z97.1 or CPSC 16 CFR 1201

Heat transfers from one place to another via convection, conduction or radiation. Convection occurs from the upward movement of warm, light air currents. Conduction occurs when energy passes from one object to another. Radiation occurs when heat is sent through space and is capable of traveling to a distant object where it can be reflected, absorbed or transmitted.

Term used for both fully tempered glass and heat-strengthened glass.

A Viracon name for a laminated glazing product introduced for hurricane protection. HRG-2 encompasses a polycarbonate core laminated between two plies of glass offering our highest level of hurricane protection.

Laminated glazing tested to one or more test protocols for high velocity hurricane winds and windborne debris.

IR is part of the solar spectrum, or sunlight, that is invisible to the human eye. It has a wavelength range of ~790-3000 nanometers and has a penetrating heat effect. Short-wave IR converts to heat when it is absorbed by an object.

Two glass components separated by an air spacer and hermetically sealed. Inherently, insulating glass increases a window's thermal performance.

An insulating glass unit inwhich the exterior component is a monolithic glass ply and the interior component is a laminated glass .

Refers to the plastic or vinyl in a laminated unit. Examples are PVB, SentryGlas Plus, Saflex HP, Vanceva Storm, etc.

Also called strain pattern or Q-lines. It is a pattern in heat treated glass not normally visible except under certain lighting conditions. It is especially visible with the use of a polarized lens. Iridescence is an inherent characteristic of heat treated glass.

Two or more pieces of glass bonded together by a piece of plastic/vinyl called polyvinyl butyral (PVB.) A minimum interlayer thickness of .030 (.76mm) meets the requirements of ANSI Z97.1 or CPSC 16 CFR 1201 safetly glazing standards.

An insulating glass unit in which the exterior component is a laminated glass and the interior component is a monolithic glass ply

The ratio is equal to the Visible Light Transmittance divided by the Solar Heat Gain Coefficient. The Department of Energy's Federal Technology Alert publication of the Federal Energy Management Program (FEMP) views and LSG of 1.25 or greater to be Green Glazing/Spectrally Selective Glazing

Another term for a pane of glass. Sometimes spelled "light" in industry literature.

An abbreviation for Low Emissivity coatings. They are applied to glass to reflect invisible long-wave infrared or heat. They reduce heat gain or loss in a building by redirecting the heat. In addition, they typically provide greater light transmission, low reflection and reduce heat transfer.

A powder used to separate lites of glass to prevent damage from scratching or rubbing.

A full size sample or model of a unit normally used to judge appearance and performance.

Refers to a single lite of glass as a finished product.

A vertical framing member separating fixed lites of glass, operating sash, or door openings.

Refers to an insulating unit wherein the two lites of glass are closer together in the center of the unit than they are at the edge. This gives the unit the appearance of being "bowed in".

an inclusion in float glass that can cause spontaneous breakage in fully tempered glass.

Either a laminated or insulating unit wherein the two edges don't match up.

An abbreviatoin for Outside-Inside Transmission Class Rating. This rating is used to classify the performance of glazing in exterior applications. It is based on ASTM E-1332 Standard Classification for the Determination of Outdoor-Indoor Transmission Class. While STC rating is based on a "White' noise spectrum, this standard utilizes a source noise spectrum that combines Aircraft/Rail/Truck traffic and is weighted more to lower frequencies.

An adhesive film applied to glass for spandrel applications.

Glass with textured surface to emit light but restrict vision.

A special fabrication done to the edge of a piece of glass. Makes the edge smooth and gives it an extremely shiny or polished appearance.

Extruded plastic sheet that can be glazed singly or as a component of a laminated glazing product.

The primary seal of an insulating unit and the key component in restricting moisture vapor transmission.

Also commonly called urethane. Used by some insulating fabricators for a secondary sealant. It is also an interlayer used in polycarbonate security products.

The plastic or vinyl used in the makeup of a laminated unit, the vinyl is what holds that unit together.

The opposite of negative air. In an insulating unit, where the center of the unit is farther apart than around the air spacer, these units have a bowed out appearance.

A process of applying a thin metallic coating to the surface of flat glass during the float glass manufacturing process.

Thermal resistance is expressed in ft^2/hr/°F/BTU. It is the reciprocal of U-value. The higher the R-value, the less heat is transmitted through the glazing material.

The RAT equation accounts for 100 percent of solar energy, which is equal to the sum of solar reflectance, absorption and transmittance. For example, with a single pane of 1/8" (3mm) clear glass, 83 percent of solar energy is transmitted, 8 percent is reflected and 9 percent is absorbed by the glass. Of the solar energy absorbed, portions are emitted back towards the exterior and towards the building interior.

See Solar Reflective Coatings

The amount of heat gained through glass taking into consideration the effects U-value and shading coefficient. Using the NFRC standard, relative heat gain is calculated as follows: English System: RHG = (Summer U-value x 14°F) + (Shading Coefficient x 200). Metric System: RHG = (Summer U-value x 7.8°C) + (Shading Coefficient x 630). The lower the RHG, the more the glass product restricts heat gain.

The appearance of waviness sometimes seen in heat treated glass caused by the glass moving over rollers in the tempering furnace.

A surface treatment for flat glass obtained by spraying the glass with hard particles to roughen the surface. The method restricts vision while maintaining a level of light transmission.

A laminate that incorporates an ionoplast interlayer which is bonded directly between two layers of glass. The product was originally marketed for hurricane protection but is also used for blast mitigating applications.

Small pieces of neoprene or other material which are placed under the lower edge of a lite of glass to support it within a frame.

Shading coefficient is the ratio of solar heat gain through a specific type of glass that is relative to the solar heat gain through a 1/8" (3mm) ply of clear glass under identical conditions. As the shading coefficient number decreases, heat gain is reduced, which means a better performing product.

Edge dimension of insulating glass covered by spacer and intended to be covered in glazing channel.

A process of applying a specific design or pattern to glass. The design is made by placing a screen over a piece of glass and then pressing ceramic frit, by means of a large squeegee, through the pores of the screen. After the frit is applied, the glass goes through an infra-red oven to dry the frit and then through a tempering furnace to fire (bond) the frit to the glass permanently.

A window glazed in a roof or ceiling of a building.

Glass units that are glazed more than 15° off vertical.

Tinted and/or coated glass that reduces the amount of solar heat gain transmitted through a glazing product.

The sum total of the solar spectrum.

The portion of directly transmitted and absorbed solar energy that enters into the building's interior. The higher the SHGC, the higher the heat gain.

The percentage of solar energy that is reflected from the glass surface(s)

Coatings that reduce heat gain through higher solar reflection.

The solar spectrum, commonly referred to as sunlight, consists of ultraviolet light, (UV), visible light and infrared (IR). The energy distribution within the solar spectrum is approximately 2 percent UV, 47 percent visible light and 51 percent IR. One aspect of the solar spectrum is its wavelength in which nanometer (nm) is the unit of length [1 nm+10^-9 m].

The percentage of ultraviolet, visible and near infrared energy (300 - 3000 nanometers) that is transmitted through the glass

The panel(s) of a wall located between vision areas of windows, which conceal structural columns floors and shear walls. Glass panels incorporate either a ceramic frit, opacifier film, or are installed into a shadow box application.

Abbreviation for Sound Transmission Class Rating. When glass is used on the building interior, the sound transmission classification (STC) value can be used to categorize the glass performance. The STC rating is a single-number rating system for interior building partitions and viewing windows. The STC rating is derived by testing in accordance with ASTM E90, 'Laboratory Measurement of Airborne sound Transmission of Building Partitions". The STC value is achieved by applying the Transmission loss (TL) values to the STC reference contour of ASTM E413, "Determination of Sound Transmission Class". The STC rating is a basis for glass selection. Its original intent was to quantify interiro building partitions, not exterior wall components. As a result, it is not recommended for glass selection of exterior wall applications, since the single-number rating was achieved under a specific set of laboratory conditions.

StormGuard™ is Viracon’s trade name for a hurricane-resistant laminate composed of an enhanced polyvinyl butyral (PVB), Solutia’s Saflex HP.

The use of a silicone sealant for the structural trnsfer of loads from the glass to its perimeter support system and retention of the glass in the opening.

The raw glass or base material to which other materials or fabrication procedures are applied.

The bottom side of float glass as it was manufactured. Called "tin side" because float glass rides on a bath of liquid tin while it is being cooled.

A measure of heat gain or heat loss through glass due to the differences between indoor and outdoor temperatures. These are center pane values based on NFRC standard winter nighttime and summer daytime conditions. U-values are given in BTU/hr/ft^2/°F for the English system. Metric U-values are given in W/m^2/°C. NFRC winter nighttime U-values are based on an outdoor temperature of 0°F (-17.8°C), an indoor temperature of 70°F (21°C) and a 12.3 mph (19.8 km/h) outdoor air velocity. NFRC summer daytime U-values are based on an outdoor temperature of 89°F (32°C), an indoor temperature of 75°F (24°C), a 6.2 mph (10.1 km/h) outdoor air velocity and a solar intensity of 248 BTU/hr/ft^2/°F (782 W/m^2).

The name of the invisible portion of the light spectrum with wavelengths shorter than 390 nanometers. The damaging effects on long-term UV exposure results in fabric fading and plastic deterioration.

Process for applying multiple layers of metallic coatings to the surface of flast glass in a vacuum chamber.

Viracon's tradename for full coverage ceramic frit products.

The percentage of light that is reflected from the glass surface(s)

The percentage of visible light (380 - 780 nanometers) that is transmitted through the glass. (Visible light is the only portion of the solar spectrum visible to the human eye.)

Application of an elastomeric sealant between the glass and sash to form a weather-tight seal.