History of Double Glazing

Double Glazing In Ancient Rome

The ancient Romans used glass in windows, but not the clear glass we use today. According to Wikipedia, they found out that insulated glazing (or “double glazing”) improved greatly on their abilty to keep buildings warm, and this technique was used in the construction of public baths. Over 2000 years later, the vast majority of Australian homes still don’t have double glazing No slouches in the field of energy efficiency, the Romans also developed underfloor heating, and the solar chimney.

Double Glazing In Europe In The 1800’s

Over 800 years later, double glazing reappears in the record in Europe, in the latter part of the 1800’s. To quote historyextra.com, “There is good evidence that some houses in Scotland had double-glazed windows as early as the 1870s. However, this took the form of a second sheet of glass puttied to existing windows. Similar claims have been made for Switzerland and Germany”

Modern Double Glazing Invented In The United States 1930

Early US Advert.
Today’s modern double glazing was developed in the United States in the 193o’s. From the 1930’s on, C.D. Haven was awarded a number of Patents. Double Glazing US Patent 2030869 A noted “…invention relates to a commercially practical, single unit multiple glass sheet glazing construction consisting of two or more sheets of glass spaced apart by separating means cemented between the glass sheets entirely around their edges. Such a product has been manufactured and sold commercially by the Thermopane Company…” The major improvement, which was a critical advance over the old-fashioned, less-effective “just adding a second pane of glass” approach, was the introduction of the vacuum between the glass panes. This enhanced both the thermal and acoustic insulation properties beyond what was possible with just two panes of glass. Unfortunately, in the 1930’s, with the United States coming out of the Great Depression, the process was expensive, and had little early success. The design required the glass panes to be of uniform thickness, and to be absolutely flat, if the vacuum gap was to be maintained, and that too was expensive. It was after WWII, in the early 1950’s, when double glazing became more economical, and was more widely adopted.

Double Glazing Takes Off In Europe

In the 1950’s and 60’s, double glazing increased in popularity in Europe- particularly in colder regions. Germany was a leader in developing new technologies, with companies like Deceuninck developing a meld of double-glazing and uPVC framing technologies. Today, double (and sometimes triple-) glazing is standard in the colder areas of Europe, the UK and North America.

A Parallel Development: uPVC As The Premium Framing Material.

parallel-development The forerunner of today’s uPVC was first developed in the 1920’s. While searching for a synthetic substitute for rubber, Dr. Waldo Semon of the B.F. Goodrich Company in the United States formulated the first PVC polymer, in 1926.

As with double glazing technology, the use of PVC didn’t come into common use until the 1950’s. As double glazing provides much better performance than single glazing, so modern uPVC window and door frames provide numerous benefits compared with the traditional wood and aluminium frames

In the case of PVC windows, known in the US as ‘vinyl windows’, Europe was the early adopter. The frst commercially viable product, the Trocal, was introduced in Europe in 1954. Production commenced in the US in the 1950’s too, but it wasn’t until the 1980’s that ‘vinyl’ took off. Read more about the History of uPVC-Vinyl Windows

Today, the pioneering advances made in double glazing and PVC polymers almost 100 ywears ago, have culminated in the best windows and doors available on the market, and proudly manufactured by Thermotek Windows, right here in Melbourne. Read more about uPVC…

Double Glazing In 21st. Century Australia

The bad news is that while Australia suffers the extremes of sub-zero Winter and searing Summer temperatures, we are far behind Europe and North America in the adoption of double glazing. Many purchasers of new homes, and the builders who build them, believe that keeping the capital cost down is the best way to improve housing affordabilty. We have another perspective…

We believe that housing affordability is best described as the cost of mortgage repayment + cost of energy. If tyhe cost of fitting double glazing is less than the energy savings you can make on your heating and cooling bills, then fitting double glazing is a ‘no-brainer’. That’s the good news.

If YOU don’t want to be 2,000 years behind the times, then Thermotek Windows is here to help. Give us a call on 1300 733 429, email us, or fill in ourContact Form

Glossary of Double Glazing Common Terms


Acoustic Insulation Acoustic insulation, such as double glazing, is used to reduce the nuisance caused by outside noise. Acoustic insulation works by reducing a sound wave’s energy.

Air SpaceThe 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.

AS 3959 Australian Standard coveringConstruction of buildings in bushfire-prone areas.IncorporatesBushfire Alert Levels (BAL)

AWAAustralian Window Association.

Awning WindowA top-hinged window that swings outward for ventilation.

BAL Bushfire Alert Levels. seeAS 3959above.

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.

Clerestory. A window near the top of an outside wall.

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 aboutcondensation.

Dormer A space which protrudes from the roof, usually including one or more windows.

Double Glazing Glazing that incorporates two panels, separated with an air space, for the purpose of thermal and acoustic insulation.

Double Hung Window A window that has two operable sash which slide vertically.

Fenestration An architectural term referring to the arrangement of windows in a wall.

Frame That part of a window assembly surrounding the sashes or fixed glazing.

French Door A particular design of swing door, all or a large part consisting of divided glass panes.

Gasket A pliable, flexible continuous strip of material used to affect a watertight seal between a sash and frame much like the seal around a refrigerator door.

GlazingThe 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.

Lintel A horizontal framing member placed across the top of the rough opening of a window or door opening to prevent the weight of the wall or roof from resting on the window frame.

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.

Pane A sheet of glass for glazing a window.

Patio DoorA 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.

Safety Glass A strengthened or reinforced glass that is less subject to breakage or splintering, such as glass for storm doors and some windows.

Sash The openingpart of the window.

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.

Tilt & Turn Windows Windows with fittings that make it possible to rotate the window through 180º so that the exterior pane is facing inwards. This is very practical when washing windows.

Triple Glazing Glazing that incorporates three panes of glass, enclosing two separate air spaces.

uPVCWAUPVC Window Alliance

U-valueAmount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality.

VCA Vinyl Council of Australia

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.

Weather Seal sash glazed with three lights of glass, enclosing two separate air spaces.

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.

WERSAustralia’sWindow Energy Rating Scheme.See our WERS Energy Rating Certifications