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Insulated Glass & Energy Savings

Insulated glass has been around for over 60 years and is constantly improving. The official definition of the term Insulated Glass (per DIN 1259 part 2) is: Insulated glass is a glass unit manufactured from two or more panes which are usually the same thickness and separated from one another by one or more gas-filled separating layers. The edges are joined and sealed against air, gas and humidity using an organic sealing material. In the airtight spaces between the panes there is either dried air or a noble gas like argon or krypton.

Thermal insulation is more than just glass

The overall thermal performance of a window is determined by multiple factors. The first variable is double glazing or triple glazing as well as the glass thickness. Naturally, triple glazing produces better u-values. Next, the glass units have air space between the panes which is typically filled with argon gas. It has a much lower conductivity value than air, reducing heat transfer. Each individual frame is also separated with a special non-conductive spacer, also called a warm edge. Combined with the spacer, each pane is sealed to the frame with silicone or a similar sealant. This helps prevent both heat transfer and condensation in the overall insulated glass unit (IGU).

Frame Material & Design

Windows are available in several different materials, each having their own insulating properties ranging from good to very good. We offer vinyl (uPVC), wood and aluminum clad wood frames. While aluminum normally has the poorest value, since it is only used for cladding, it still works well with wood. This results in both a tougher, more weather resistant window but also better insulation values in the IGU overall. For modern vinyl windows, frames today are designed with multiple chambers to improve their insulating properties. Depending on the frame profile selected, the number of chambers can vary and whether or not they are additionally filled with insulating foam.

Insulated glass window

Combined with modern glass units with a low conductivity spacer, argon, a good seal and multiple glazing, you can achieve excellent thermal performance and save a good deal on heating and cooling costs in the long run.


The u-value or u-factor, measures heat insulation and is calculated for each individual component and combined for the window unit as a whole. This is then known as the heat transition coefficient. For windows, it can be broken down into three values:

  • Ug-value, for the glazing
  • Uf- value, for the frame
  • Uw- value, for the complete window unit

Additionally values are calculated for the so-called heat bridges; these are created between the frame and the surrounding masonry and also between the individual glass panes.

The unit of measurements for these values are given in Watts per square meter and Kelvin, W/(m²K).

Choosing the Right Glass

As well as the frame selection the right choice of glass is decisive for achieving the best insulation for your home. For each of our frame materials, we offer four different insulated glass options, divided into double and triple pane units. They offer Ug-values between 0.6 und 1.1 W/(m²K). These figures measure the heat flow through the window (i.e. heat loss). Therefore lower values are better.

It is particularly important with multi-layer IG units that the argon gas between panes cannot escape. This is where edge sealing is critical. A two stage adhesive seal element holds the panes tightly together while simultaneously keeping them at the prescribed distance apart from each other. Seal failure leads to reduced a reduced u-factor, heat loss and potential moisture buildup between panes not to mention wasted energy.

Finally, insulated glass can also be combined with laminated safety glass, soundproof glass and more. It is not a case of one or the other, so you can get the exact combination of features to meet your home's unique requirements.

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