Insulating Glass Units

Double glazed units, or IGUs, perform better than single glazed units and have rapidly become the norm in the Australian building industry. Glassworks has one of the most advanced IGU lines in Australia, servicing our window customers and their customers’ individual IGU needs. 
LoE 366. Sorrento residential living room portrait

Why upgrade to an IGU

Opting for an IGU over a single glazed unit is always a worthwhile investment and might soon become mandatory as Australian building requirements tighten. Simply put, a house that’s worth building or a window that’s worth installing is surely worth double glazing.

As the name suggests, IGUs offer more insulation, for better temperature and noise control, as well greater energy savings and safety. The main reasons for specifying IGUs are as follows:

  1. Energy savings: The thermal insulation of an IGU means less reliance on artificial heating or cooling to stay comfortable inside a building. Incorporating a low-E coating further adds to this
  2. Safety/security: IGUs are inherently thicker and tougher to break, making them more resistant to intrusions and damage in natural disasters
  3. Fade protection: Reducing the amount of prolonged exposure to sun and heat protects furniture and fittings from fading (depending on make-up)
  4. Less condensation: The airtight gap between the two panes of glass prevents condensation which can turn to frost in winter, making it difficult to heat a room up
  5. Noise reduction: IGUs absorb outside sounds for greater acoustic comfort. Incorporating an acoustic laminate further combats noise (depending on make-up).

Please note that while installing an IGU may ‘tick the box’, the glass type, coating, spacer, and framing system used also play an important role in window performance.

The surfaces of an IGU

When an IGU is made up of two pieces of flat glass on either skin, the surfaces are counted from the outside. Surface 1 is the exposed surfaces facing the exterior of a building, surface 2 is the opposite side inside the unit, surface 3 is inside the unit closest to the room and surface 4 is the exposed surface on the room side.

​If acoustic dampening is required, the first piece of glass (surface 1 and 2) maybe substituted with an acoustic laminated product to absorb the noise, or if seeking additional thermal performance, a low-E coated glass may be used on one or more of the surfaces. See what is low-E glass for more information.

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Inside an IGU

The gap inside an IGU is known as an Air Gap. They vary in width from 6mm to 20mm, usually determined by the width of the frame and thickness of each piece of glass. The default type is 100% Air or there is the option of Argon gas, which is 90% Argon 10% Air. Argon is used to lower the U-Value if this is required.

The default spacer type offered by Glassworks is Aluminium, or there is also the option of a SuperSpacer which further slows the heat transfer through the window for an even more insulating effect.



A ‘warm-edge’ technology which is less conductive than conventional aluminum spacers with the unique ability to slow the heat transfer from the frame to the glass resulting in energy savings.

​Being the most flexible of all spacers, the SuperSpacer is more resilient to common stress factors and able to maintain its smooth appearance. The thermoset silicon polymer material expands and contracts and always returns to its original shape. 

​Glassworks offers the SuperSpacer alongside aluminium spacers on all IGUs.

Related products

Glassworks double glazed IGU products

EnerSave 1

EnerSave® IGUs >>

Double glazed Insulating Glass Units in a variety of glass types, coating options and air gaps

LoE 366

LoĒ³-366® clear double glazed >>

A neutral coloured triple silver low-E offering the ultimate balance of year-round thermal comfort and visibility

LoE 340

LoĒ³-340® solar control double glazed >>

A blueish coloured triple silver low-E with superior solar control for commercial facades

LoE i89

LoE-i89® clear single or double glazed >>

A smoother and clearer low-E glass able to be single or double glazed


Optitherm® clear double glazed >>

A super clear and insulating low-E perfect for colder climates at the perfect price point