17. December 2025

Ceiling Lighting in Earth-and-Timber Slabs

Artificial light helps shape the atmosphere day and night, as here at Hortus. ©Maris Mezulis, Herzog & de Meuron
In design, great importance is placed on the natural lighting of interiors. Just as important, however, is the lighting design of the artificial light, which shapes how people perceive atmosphere, spaces and materials. Ceiling lighting is used frequently because it allows large-area, flexible application without taking up any space in the floor plan. The connections for it have to be planned in early, though, to allow efficient prefabrication and installation. In earth-and-timber slabs there is also the structured grid, which has to be factored into the design and the positioning. In our projects to date we have realised two options, which we present here.
At Hortus the cables are routed loosely and visibly where they run across the joists. ©Maris Mezulis, Herzog & de Meuron

“Surface-mounted” installations

On the Hortus project, the principle of system separation was implemented in the spirit of sustainable building. All technical installations were routed visibly so that later maintenance and any renewals remain flexible and independent of the structure. The cable routing of the ceiling lighting is exposed and fitted on site afterwards, without inlays or drilling. Herzog & de Meuron picked this up skilfully at Hortus and made it part of the design.

 

Parallel to the joists, the cables were routed visibly in brown cable trunking. ©Herzog & de Meuron

Recessed ceiling connections

As part of another new build, recessed ceiling lights were developed together with ERDEN Studio and gbd. The recesses are milled directly into the timber element and worked into the rammed earth. On site they can then be fitted with either spotlights or pendant lights.

The luminaires can be suspended from the recessed sockets or work as spotlights © Lehmit GmbH, Hanno Mackowitz
More insights to discover
We develop building systems from earth and timber to combine the strengths of both materials in the best possible way. ©Lehmit
8. January 2026

Brochure Building Systems in Earth and Timber

With the new Lehmit Compendium, we provide a compact resource that brings together our knowledge and experience in building with earth and timber – ready to print or share. The brochure highlights the advantages of this hybrid approach, ranging from acoustic performance and indoor climate to fire safety and circular construction with minimal embodied energy. It presents innovative ceiling, interior wall and exterior wall systems, as well as the entire project process from planning through to realization. The handbook is aimed at architects, clients and companies seeking sustainable, resource-efficient and technically advanced solutions in earth-and-timber construction for their projects.

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