Les Jumeaux

The Challenge

Les Jumeaux (The Twins), two former warehouses built in the heart of Lausanne’s Flon district between 1894 and 1896, are two major examples of Switzerland’s industrial heritage. Constructed using the innovative reinforced concrete technique patented by François Hennebique, they are listed with a grade of two in the Swiss heritage inventory, indicating their historical and architectural value to the region. After more than a century of successive adaptations, these iconic buildings required a profound transformation to meet contemporary needs, all while preserving their historical integrity.

The project had the dual ambition of preserving the architectural and heritage identity of the buildings while infusing them with a new functionality. This challenge also involved providing optimal thermal and visual comfort in largely open and glass-walled areas, without compromising the aesthetics of the premises.

The Solution

The designers opted for an approach that respects the industrial character of the buildings. The interior spaces were opened up to reveal Hennebique’s structure, and the majority of the decorative elements on the façade were preserved or even restored. The alley separating the two buildings was transformed into a covered gallery by creating a double-pitched glass roof, connecting the buildings and offering a unique light-filled space. Glazed openings were made on the south façades to open up the entire complex onto Place du Flon, radically modifying the buildings’ original orientation.

Selecting SageGlass electrochromic glazing for the glass roof and large openings proved to be an innovative and decisive solution. This smart glazing, which can automatically tint or clear depending on the external light conditions, made it possible to meet the requirements for comfort and energy performance. With SageGlass, light and heat management is dynamic, reducing glare and overheating without the need for blinds. This technology blends seamlessly with the architecture, preserving the transparency and purity of the lines while contributing to the project’s overall energy performance in synergy with the interior insulation and the photovoltaic panels installed on the roofs.

The Benefits

The integration of SageGlass into the glass roof and the major openings provided significant benefits. Occupants benefit from optimal visual and thermal comfort regardless of external conditions, promoting a pleasant experience in common areas and workspaces. Aesthetically, SageGlass made it possible to preserve the transparency and brightness of the spaces without compromise, eliminating the need for shading components that would have altered the architectural design. Finally, this innovative solution aligns perfectly with the environmental and energy objectives of the project, offering a modern and sustainable answer to the challenges posed by the rehabilitation of historic buildings.