1992

In 1992, Michel Trompert noted a growing trend of replacing historic windows featuring sash windows with modern window systems. At that time, gasketing and achieving the lowest possible U-value had already become the standard practice.

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In an effort to address cultural degradation, Michel Trompert collaborated with TNO and the Rijksdienst voor Cultuur to develop a worthy successor to the 350-year-old sash window. This new design eliminated draughts and was compatible with insulation glass. In 1994, Trompert's patent for this innovative technique, named WinTwin, was granted. The same year, the traditional window featuring this new technique was launched at TNO. This marked the initial step towards the eventual realization that achieving thermal efficiency and cultural preservation necessitated more than just sealing gaps and achieving the lowest U-value.