It’s always nice to see large companies acting responsibly and it is even nicer to see them building their business headquarters sustainably. Ricola, the makers of herbal cough drops from Switzerland, have recently unveiled a new herb processing center that is build out of mud. The work was carried out by Herzog & de Meuron, and the walls of the center were made out of rammed earth under the watchful eye of Martin Rauch of Lehm Ton Erde (Loam Clay Earth). The building will be used for the drying, cutting, blending and storing the herbs as part of the production of the cough drops.
The benefits of building with rammed earth include better temperature and humidity stabilization due to the fact that the thick walls have great thermal mass. This reduces the need for air conditioning considerably. The rammed earth walls are made from locally sourced dirt obtained from a location less than 10 kilometers away. The panels are then prefabricated in a temporary factory in a nearby town. This of course greatly reduced the carbon emissions.
The walls are made of clay, marl and other materials, which are then mixed and compacted in a formwork and layered in blocks to build the walls. Due to the pliant nature of the material, all seams can easily be retouched, which gives the building a more homogeneous appearance. To fight wind and rain erosion, a layer of a trass mortar (made by mixing volcanic tuff, or trass, with lime), is added for every 8 layers of the rammed earth directly in the formwork.
These white mortar lines also act as overhangs that prevent the washing away of the earth in the walls. There is no concrete mixed into the walls as is sometimes the case with other mud houses. With this new headquarters structure, the builders aim to prove that mud is not just for building huts anymore. However, the considerable weight of the rammed earth wall panels does call for a strong and durable framework.