08/23/2018 / News

A spacer makes history

In 1993, the world’s first co-extruded spacer profile for the Warm Edge of insulating glazing was launched

A material mix of plastic co-extruded with metal gave the new thermally optimised insulating glass spacer its name: Thermix. The company of the same name was founded by Georg Greubel, a resourceful glass expert from Altshausen near Ravensburg, in 1993. And as early as 1994, series production was commenced by its development partner Ensinger, which ultimately acquired full control of Thermix in 1997.

“Switching as easy as possible” 

“We have designed the product to make switching to it as easy as possible for insulating glass manufacturers”, explains Heinz Raunest, who in his capacity as an application engineer at Ensinger has been involved with Thermix since the very first metre was produced. “The profile rod was capable of being processed on existing lines without major investment or training of the employees.”
But Thermix was somewhat ahead of its time. In the 1990s, the standardised energy assessment of windows and façades did not even take account of the thermal bridge in the transition zone from glass to frame. Consequently, it was difficult to convey to many customers the added value offered by a Warm Edge. However, the architects from the growing passive house movement quickly recognised the benefits of Thermix.

Development milestones

In November 2000, DIN EN ISO 10077 entered into force. The Psi value as a linear thermal transmission coefficient for the thermal bridge at the glass edge was now incorporated alongside the area-weighted values of glazing (Ug) and frame (Uf) into the calculation of the U value of windows (UW). Thermally improved spacers got a significant boost as a result, and this was further reinforced as legislation imposed ever greater requirements on heat insulation.

In parallel to developing the market, Ensinger has also continued to develop Thermix over the years, expanding the product range in line with the growing requirements.

Milestones in Thermix product development from 1993 to 2018From 1993 to the present day: milestones in Thermix product development

No end in sight

Today, the market offers a number of versions of the Warm Edge spacer: rod profiles made from stainless steel that can be processed into frames and hybrid profiles made from plastic and stainless steel or composite film, as well as flexible systems which are applied from the drum (thermoplastic spacers, TPS) or from the roll (foamed profiles) to the panes. Two thirds of all windows produced in Germany today have thermally optimised spacers – but why not all of them by now?

“Energy-efficient construction is a complex topic where visionaries constitute the upper defining limit and regulators the lower defining limit of the market”, says Heinz Raunest, who supports Thermix customers across the globe. “But it is quite simply like this: a spacer that insulates well, when used instead of aluminium, improves the U value of a window by 0.1 to 0.2 W/m2K – with a UW of 1.0 W/m2K this corresponds to ten percent. Regardless of whether a room is being heated or cooled, there is barely a component that pays off more quickly. This goes for the wallet, living comfort and the environment.”

Click here to read the entire history, with additional facts about the development of the edge bond of insulating glass.