How warm edge spacers were developed, and why they increase the energy efficiency of buildings so successfully
Sustainability, climate protection and the safeguarding of resources and a healthy environment for future generations are key issues for all manufacturing industries today. The construction sector was one of the first to acknowledge these concerns, and it is now setting exemplary standards in energy-efficient building methods. An important element in this is the optimised insulation of windows, doors and façades. Highly insulating spacers such as Thermix® from the German plastics specialist Ensinger have contributed to the sustainable increase in energy efficiency and living comfort achieved by modern insulating glazing. However, the foundations for this achievement were laid more than 150 years ago.
Milestones in the development of the insulating glass edge bond
In 1865 Thomas D. Stetson, an American, files a patent for double glazing. Dehydrated air is used for the insulation between the glass panes, which are glued together. Stetson has also already come up with the idea of thermally separating spacers. But the materials and sealants he uses are too permeable. The insulating glass is not gas-tight in the long term. Some 65 years later, in 1930, the American engineer C. D. Have takes the idea further. He uses metal spacers which are hermetically soldered to the glass. This type of insulating glazing becomes increasingly popular in North America and Europe over the following years. In 1955 an insulating glass without an edge bond arrived on the market. Here the glass panes were fused together at the edges and offset. In 1959 the German glass finisher Alfred Arnold develops the organically glued edge bond with a metallic, hollow profile perforated towards the space between the panes and an elastic sealant. The method is developed further to become the edge bond glued in two stages which is customary today. In the 1980s the term “warm edge” is coined in the USA. It comprises all spacers which are thermally improved compared with aluminium.
Thermix: The pioneer of a new generation of spacers turns 25
The next major step forward in the history of the insulating glass edge bond comes in Germany in 1993, when Georg Greubel, operating under his company name Thermix in partnership with Ensinger, develops and launches the first thermally optimised and coextruded spacer made from highly insulating plastic with a thin diffusion barrier made from stainless steel. The advantage: Thermix® can be processed on existing facilities almost as easily as metal. Corner connectors and muntin bars are soon added to the portfolio.