Text description provided by the architects. The building is located in the district of Bonnevoie in Luxembourg City, at two steps from the central station. Lively, central and intense quarter, close to public transport in order to limit car use.
It is a small urban building, well-insulated (class A) and "low-tech", with a sales area of 110m2 on the street level and five office levels at around 125m2 each. An atypical concrete structure, designed with Marc Ewen from the office Au Carré, including variable thickness slabs, offers an open space of 11×12m.
The windowsills are inverted beams, allowing windows to touch the ceiling to maximize the entry of natural light. The majority of the walls are pre-made concrete walls, left exposed. The onsite casted concrete slabs and veils are also remaining apparent, with their flaws and irregularities. Solid oak floors bring warmth and a noble finish that presents the contrast to the structural work.
The staircase, designed to be as compact as possible, is rather special: polished crude steel, a large central sheet of more than 15m high which is suspended from the roof slab; steps are folded metal sheets that are attached to the concrete walls and to the central sheet via spacers that allow the light drag along the walls.
Low-tech and AAA, this building is very well insulated and equipped with triple glazing, optimizing generous natural lighting and framing the beautiful views of the impressive scenery of the nearby urban train station and Rotondes, with forests and fields lurking in the background of the south of the city.
Automatic external shading devices limit the external heat load in summer and natural ventilation through automated windows reactivates the thermal inertia of the concrete slabs during cool summer nights. No air conditioning system had to be installed.
The mechanic ventilation of workspaces is done by individual VMC on each floor, which have a particularly high heat recovery efficiency. They avoid heavy ventilation units and distribution ducts throughout the building. The heating, if applicable, benefits from the connection to the urban heating and is therefore limited to simple distribution pumps and calorimeters.
The facade is made of charred regional larch cladding. Its surface is burned with a blowtorch in the yakisugi* japanese traditional way. The black charred layer is very hard and forms the natural protection of the wood.