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A Reactive Thermoplastic Spacer with Excellent Durable Energy Efficiency for Structural Glazing Facades

A Reactive Thermoplastic Spacer for Structural Glazing Facades

Posted 12/04/2018 by Mike Speicher, Market Manager

Minimizing the energy consumption of buildings has become a global objective and an important goal in building design and construction. The future will see a continuous tightening of energy efficiency standards on an international level and of the energy performance level of building envelopes.

 To meet the demand for primary energy sustainability, an optimized thermal insulation - especially in the facade and window surface of buildings - has to be ensured. As a result of highly effective glass coatings and energetically optimized facade and frame profiles, gas-filled double and triple pane insulating glass units (IGUs) have developed into highly thermal insulating assembly parts. Therefore, optimizing the thermal insulation performance of the edge seal has become the focus of attention.

Traditional aluminum spacer systems create a significant thermal bridge in the edge seal and are affecting the thermal properties of IGUs and reducing the energy efficiency of the building envelope. On this background, a wide variety of spacer systems - so called warm edge solutions - have been developed to reduce this thermal loss. As long as it improves thermal performance than the traditional aluminum spacer, even at a relatively small level, it was considered to be warm edge.

While stainless steel and other metal-based spacer systems can offer some improvement over traditional aluminum spacers in terms of condensation resistance and U-values, it's undeniable that they are still 80 times more conductive than state-of-the-art, high-end warm edge spacer systems. Metal-free thermoplastic spacers represent such high-end warm edge systems. They offer the lowest level ψ-values, which lead to improvements in the Uw values of the window and the Ucw values of structural glazing elements. Compared to the ψ-values of the edge seal, the contribution of gas-filling plays an even more important role for superior thermal transmission coefficients of double or triple glazing. To maintain the low Ug-values for the lifetime of a facade IGU, only the lowest gas loss rates are acceptable.

With many new warm edge spacer systems, large facade units are not easy to produce. There also is a growing discussion about the durability of edge seals, especially in more challenging climates and edge loads. Modern structural glazing facades with gas filling and warm edge are highly demanding on the edge seal. Additionally, a secondary sealing with silicone, which has inherently no gas retention capability, is often mandatory due to its UV stability. It is somewhat difficult to produce durable gas-filled IGUs with silicone secondary sealing. However, there is a growing demand for such units for structural glazing facades. The gas will only stay inside the IGU with an absolutely tight primary butyl seal – for conventional edge bond with spacer profiles this is a nearly impossible demand. With focus on the use in structural glazing applications, the new generation of thermoplastic warm edge system has been developed.

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