Contact Phones
Canberra: (02 6280 5300) Melbourne: (1300 932 202) Sydney: (1300 932 202)


About us

Just Rite is a Canberra based company that has been serving Canberra community since 1977

Contact Phones
  • Canberra: (02 6280 5300)
  • Sydney: (1300 932 202)
  • Melbourne: (1300 932 202)

Properties of Double Glazed Units

Types of Glass


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Normal everyday glass. Glass is manufactured by melting sand, soda ash, dolomite and limestone together and produces a continuous glass up to 3660mm wide. This flows from the furnace and "floats" over a bed of molten tin. It is then carefully cooled to anneal the glass - a process which modifies the internal stresses enabling it to be cut and which maximises its potential mechanical resistance. The float glass process is renowned for flatness and optical clarity. It is available in clear, tinted, toughened and Low E coated.


ResizedImage280185 Ocean Bule Laminated Glass

2 pieces of glass bonded together by a plastic or resin interlayer. Laminated glass is a type of safety glass that holds together when shatterd. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral (PVB), between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass. This important breakage characteristic significantly reduces the likeihood of serious injury, qualifying laminated glass as a Grade a Safety Glass in accordance with Australian Standards.

Absorbs 99% ultraviolet (uv) rays thereby helps protect your furnishings against fading. Noise Control the layer in the middle of the two pieces of glass dampens sound - great to block out traffic, dogs, aircraft, trains etc.

Increase security it's more difficult to penetrate due to it's strength. When subjected to human or other impact, the bond between the glass and interlayer adheres any brocken fragments keepoing the galss intact and resisting penetration.

Toughened Glass

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Toughened or tempered glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering creates balanced internal stresses which cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards. The granular chunks are less likely to cause injury. Fully toughened glass is four to five times stronger than ordinary glass and used in areas a specified by AS Safety Standards.

Tinted Glass

There are many types of window tint available in the market for a wide variety of uses from solar heat reduction to UV protection, privacy to safety and security, decorative applications to heat retention.

Tinted glass can be toughened, laminated or incorporated into an insuating glass unit. Under certian light conditions a smnall degree of haze may be apparent. Low E (low emissivity). Low E increases the insulating effect, heat loss = energy saver. At manufacturing a process is applied to enhance the insulating when made into a double glazed unit. Low E glass stands for low emissivity glass. This glass varies from normal clear glass in that one side of the glass has a special metal coating, technically known as a low emissivity, or Low E Coating.

Low E glass is a type of insulating glass, which increases the energy efficiency of windows by reducing the transfer of heat or cold through glass. That means in the winter your house stays warmer and in the summer it stays cooler. As energy saving will become more and more important in our daily lives, implementing Low E glass in our houses will soon be a standard we all have to comply to.

Argon Filled Units 

Argon Gas is an inert gas. It is not harmful. The argon is sealed within the unit at the time of manufacture and this increases the insulated properties of the unit. Argon gas is denser than air and acts as a greater barrier to heat loss and heat absorption in the home with a thermal performance increase of up to 15%. We offer the best possible price and installation service within Canberra, Sydney and Melbourne whether you are a homeowner, builder, tradesman or renovator.  

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Thermal Properties of Double Glazed Units


Whether there is direct sun on a window or not, heat is still pouring through a conventional glass window. Heat can travel in three ways:

  1. Radiant heat is felt from the direct sun
  2. Convection is the transfer of heat by a current of air (e.g. either ‘natural' convection - warm air rises, or 'forced' convection - a breeze by a window, both of these can result in a draught by a window
  3. Conduction is heat moving through an object (i.e. heat will travel through an aluminium, or steel frame more easily than through a timber or PVC frame)

U – Value

U Value – measurement unit is watts per m2 per degree Celsius (W/m2°C) and is a measure of the rate of heat gain or loss through glazing due to environmental differences between outdoor and indoor air.

U represents the heat transfer through a window irrespective of direct sunlight. For example, heat still moves through a closed window at night-time. The U-value is specific to windows and glass and is the inverse of the commonly used R-value, which is used for insulation properties of walls and other building materials. For this reason the lower the U-Value the better the insulation performance. The U-value is important for measuring the heat transfer both in and out of the window. The more heat transfer that the window can resist the better an insulator it is. It can either stop the heat from coming in on a hot summer day or stop the heat escaping on a cold winter evening

Solar Heat Gain Coefficient (SHGC)

SHGC (Solar Heat Gain Coefficient) – the proportion of total solar radiation that is transferred through the glass at normal incidence. It comprises the direct solar transmission and the part of the solar absorption dissipated inwards by radiation and convection. The lower the number the better the solar performance.

Is a fraction that is used to indicate the amount of radiant heat that can travel through a window. This coefficient is largely affected by direct sunlight, which is radiant heat. The lower the SHGC, the better the material will stop solar heat coming into the building through the window. A low SHGC is like having a very effective shade over the window, except that the view will be less restricted. In the summertime it is important for this number to be as low as possible as we are trying to minimise unwanted solar heat gain. In a winter climate we are trying to keep this number as high as possible as it is important to let the solar heat in but not let it out.



In winter the ideal situation is to let in as much of the sun's heat and then trap it inside to maintain a comfortable environment in your home or office. This will also greatly reduce heating costs and directly relate to money savings. The ideal window for winter will have a high SHGC to let the sun's heat in and a low U-Value to prevent the heat from escaping. Clear windows without shading films are better suited for winter climates.


In summer the ideal situation is to minimize the heat coming in from outside and prevent the cool air inside from escaping through the window. This will make your home more comfortable and reduce your air-conditioning costs. The ideal window for summer, or for a large west-facing window, will have a low SHGC to limit the heat from the sun's direct rays, as well as, a low U-Value to prevent the heat in the air outside from moving through the window and warming the cool conditioned air inside. It is better to have a shading film on the first (outer) glass pane to limit the heat that enters the double glazed unit.

Glass Thickness U SHGC Reduction in Heat transfer Reduction in radiant heat
Clear 3mm glass 5.9 0.86 N/A N/A
Clear 4/12/4 2.7 0.85 54.24% 1%
Bronze 4/12/4 2.7 0.58 54.24% 32%
Lowe E-Clear 4/12/4 2.1 0.55 64.41% 36%
Lowe E-Bronze 4/12/4 2.1 0.43 64.40% 50%

Reductions are worked on compared to 3mm float glass 
Using Argon instead of air there can be a further 3% improvement

Detail Thermal Properties of Glass

Glass Performance Data - Energy 

Acoustic Properties of Double Glazed Units

Noise Data

Noise pollution is one of the biggest problems faced in cities today. Unwanted noise can be responsible for sleep loss and lack of concentration. This can lead to a deterioration of health through increased stress levels, headaches, high blood pressure and loss of hearing.

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Expert Advice:

Research by Dr. John Davy at the CSIRO has shown that secondary windows will reduce more noise than single glazed windows or even traditional double glazed units. This is due to the large buffering air cavity between two windows. The larger the air cavity the more noise the window system can reduce. Noise has wave properties. This means that noise can pass through a window in two ways:

Crack space or poor seals are responsible for letting noisy air enter through small spaces, allowing noise to amplify once inside.
Vibration allows noise to travel through solid objects increasing noise levels inside.
This means that to effectively reduce sound levels a window system should have minimal air infiltration and possess enough weight to limit vibration.