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An Introduction to Insulating Glass


A William Lingnell, PE, Lingnell Consulting Services / IGMA Technical

Consultant

June 2011

©Insulating Glass Manufacturers Alliance (IGMA) March 2010. This presentation and contents is the exclusive property of IGMA and may not be distributed, copied in whole or in part without the express written consent and authorization of IGMA. All rights reserved.


  TOPICS TO COVER

  History of Insulating Glass   What is an Insulating Glass Unit   Use and Types of Insulating Glass   Energy Concepts for Insulating Glass   Materials Used in Insulating Glass   Fabrication of Insulating Glass


  History of Insulating Glass

  Thomas D. Stetson, Inventor   Received patent in 1865

  What did he do?


  What is an Insulating Glass Unit?

  Insulating Glass Units are sealed combinations of 2 or more lites of glass separated by a dry air space.

  And what do they do?   Insulating Glass Units save energy, save

money, reduce pollution and greatly improve the comfort inside a building.


Large Commercial Project Investigated


Seal Failure in Wood Window with True Divided Insulating Glass Lites


Schematic of an Insulating Glass Unit

Outside Inside


USE AND TYPES OF INSULATING GLASS

GLASS TYPES

  Clear Glass: soda lime, low iron   Tinted Glass: green, gray, bronze, blue, blue green   Reflective Glass: pyrolytic, sputtered   Low Emissivity Glass: pyrolytic, sputtered   Laminated Glass: monolithic, insulating, PVB interlayer,

ionoplast interlayer, urethane interlayer, silicone interlayer, resin interlayer

  Patterned Glass: sand blasted, chemically etched, rough rolled


GLASS TYPES

  Spandrel Glass: ceramic frit opacification, film opacification, silicone opacification

  Hydrophilic Coated Glass: self cleaning, easy to clean   Fire Rated Glasses   Wired Glasses   Electrochromic coatings


GLASS KINDS   Annealed

  Heat Treated –  Heat-Strengthened –  Tempered

  Chemically-Strengthened


USE AND TYPES OF INSULATING GLASS

Insulating Glass Units are used in a variety of applications including windows, doors and skylights for commercial buildings and residential construction as well as in refrigeration units, control towers, rail transportation, cars and busses, marine applications and many other areas where energy conservation and comfort are part of the design.


Energy Concepts for Insulating Glass

Terminology   U-factor (U-value) - The measure of the rate of non-solar

heat loss or gain through a window system in terms of Btu/hr-sq ft·ºF (W/sq m·C) . The lower the U-factor the greater the resistance to heat flow…..a better insulator.

  R-value - The measure of the resistance of a glazing material or fenestration assembly to heat flow. Basically the inverse of the U-factor or R = 1/U

  Solar Heat Gain Coefficient (SGHC) – The fraction of the solar radiation admitted through a window or skylight both transmitted and absorbed and released inward.



Single Pane 1930’s (+ Storm Panel = R 2)

Double Pane IG 1950’s (Welded Edge)

Triple Pane IG 1979

U-Value = .50 R-Value = 2.0

U-Value = .33 R-Value = 3.0

U-Value = 1.0 R-Value = 1.0

 SHGC = 0.87

 SHGC = 0.77

 SHGC = 0.71



LoE Air Fill   ‘1983

LoE Argon

‘1987

LoE Argon   ‘1995 Solar

Control

U-Value = .30 R-value = 3.2

U-Value = .25 R-value = 4.0

U-Value = .25 R-value =4.0

 SHGC = 0.62

 SHGC = 0.62

 SHGC = 0.40


Energy Concepts for Insulating Glass Terminology   Conduction - Heat transfer through a solid material by

contact of one molecule to the next.   Convection - Heat transfer involving the motion of a fluid,

like air, caused by the difference in density of the fluid and gravity….allows heat to transfer from glass surface to room air and between two lites of glass.

  Radiation - Transfer of heat in the form of electromagnetic waves from one surface to another, the sun reaches the earth by radiation and a body will lose heat to a cold window in a similar way.


How does glass insulate?

Glass is conductive, the insulation is the air that clings to the surface of the glass.



Times two

Can I build a unit that will retain gas?



Low E cools surface #1 and warms surface #4

making conduction of the fill gas more important.

What happens now?



"Buyers expect a lot of big windows," said Scott Parkin, principal with Hoffman Parkin Urban Realty and sales manager at Cobalt, the Minneapolis condo building where Hengel recently bought her home. "Everyone knows the technology is there; 50 years ago, you couldn't do it [glass-walled units], you'd lose so much heat," Parkin said. But today's engineered glass, with double panes and a layer of

practical and desirable.



.30

.32

.35

.60




  Terminology

  Low-emittance (low-E) coating- Microscopically thin and virtually invisible metal or metallic oxide layers deposited on the glass to reduce the U-factor by suppressing radiative heat flow.


Terminology   Transmittance – The percentage of radiation that can

pass through glazing for visible light, ultraviolet or total solar.

  Reflectance – The ratio of reflected radiant energy to incident radiant energy.

  Absorbtance – The ratio of radiant energy absorbed to the total radiant energy in a glazing system.

  % Transmittance + % Reflectance + % Absorbtance = 100%



Materials Used in Insulating Glass

  Glass   Coatings   Spacers   Sealants   Desiccants   Gases

 Spacer Types – Single Seal

Spacer

Glass

Sealant

One sealant must perform dual function: prevent moisture transfer into airspace and hold unit together through long-

term weathering



Spacer

Glass

Structural Sealant

Gas Barrier Sealant

Primary Seal (gas barrier) selected to prevent moisture

transfer into airspace Secondary Seal (structural) selected to hold unit together through long-term

weathering Typically 10 year

warranty

Spacer Types –Dual Seal

Glass

Structural Sealant

Gas Barrier Sealant

Aluminum Spacer

Corrugated MetalStrip

Desiccated Sealant

Desiccated Sealant

Glass

Spacer Types

Aluminum Butyl


Barrier Film

Spacer

Glass

Sealant

Desiccated Foam

Spacer

Glass

Sealant

Desiccated Matrix

Spacer Types

Foam Roll Formed



Stainless Steel

Spacer Types

Stainless Steel


Sealant Functions

  Gas & Moisture Barrier   Chemical Fog Resistance   Long Term Durability   Thermal Performance   Structural Capacity of Unit


Sealant Types

  Hot Melt Butyl   Polysulfide   Polyurethane   Polyisobutylene   Silicone   Extrudable Polyurethane

 Adsorption is a process that occurs when a gas o r l i q u i d s o l u t e accumulates on the surface of a solid or a l i q u i d ( a d s o r b e n t ) , forming a molecular or a t o m i c f i l m ( t h e adsorbate)

Desiccants



Desiccant Types

  Molecular Sieve   Silica Gel   Blended Desiccant   Desiccated Matrix


Fill Gases

  Purpose (only) to reduce U-value   Inert Gas-does not react   Does not change SHGC, SC, Transmission,

Reflectance, UV transmission, STC


Types of Fill Gas

  Argon   Krypton   Xenon   Blends   Sulfur Hexafluoride


Fabrication of Insulating Glass   Cutting   Washing   Heat-Treating   Coating   Washing   Spacer Assembly   Inspection-Quality Control   Sealant Applications   Assembly and Pressing   Sealant Curing   Packaging and Handling   Shipping

Fabrication of Insulating Glass


An Introduction to Insulating Glass Fabrication of Insulating Glass


Fabrication of Insulating Glass

Insulating Glass Installed in a Bridge



Acknowledgements

  Insulating Glass Manufacturers Alliance (IGMA)   Cardinal IG   FDR Design


Questions?

Contact IGMA [email protected]

613-233-1510

©Insulating Glass Manufacturers Alliance (IGMA) June 2011. This presentation and contents is the exclusive property of IGMA and may not be distributed, copied in whole or in part without the express written consent and authorization of IGMA. All rights reserved.

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