We put our knowledge at your service to carry out all your projects.
Office Building, Orangerie, Lyon (69), France © Patrice Pattee
Awarding authority : Ogic
Project manager : Clément Vergély architectes
In Lyon Confluence, in France, the Orangerie is a building symbol of the renewal of rammed earth as a building material. Taking on a real challenge, the various actors in this major project have succeeded to achieve a feat in a context not very favorable to the use of rammed earth in the construction sector.
This is how the Orangerie stands in the heart of the Confluence eco-district, a 1000m² office building on 3 levels, which stands out from its concrete comrades. Designed by Clément Vergely agency and associated with Diener & Diener Architekten, the project wanted that each block in the district had to integrate or keep buildings of lower height, introducing a variation in scale and reminiscent of the market halls.
The use of that contemporary technique of rammed earth in prefabricated elements on site and assembled in position is the reappropriation of a traditional and ancestral constructive process of the Rhône-Alpes region still very present in the heart of Lyon. Indeed, Lyon is one of the cities in Europe with the largest concentration of urban pisé construction, most often high-rise buildings built until the end of the 19th century.
Following the traditional technique of pisé, the arches of the massive faces of the building in compacted rammed earth are implemented in a modern way by a process consisting in prefabrication on site, or in the immediate vicinity, large blocks (2.50 / 3.50m long and 1m high) and mounting them directly (or after a phase of temporary storage and drying), in the manner of freestone masonry, to form the sections of walls made up of corner pieces, segments and keystones.
This process gives the building a raw character that refers to the prefabricated concrete construction of the flower markets on the neighboring islet and the stone architecture of the vaults of the Orangerie in the Tête d'Or park, going beyond the regional and traditional architecture of land constructions in the Lyon region. With a uniform layered hue, the facade color is punctuated by the gradian of each bed of compacted earth, with a gradient hue and a brushed finish with visible aggregates.
The structure design office Batiserf, ensured the design from the competition, where the loadbearing facades in pisé with the form of inverted chain arches were already present, alongside the designer architects within the project management team. The prefabricated elements of the arches of the loadbearing facades were made of unstabilized raw earth, without any addition of additives, with a "natural" earth in order to keep all the environmental qualities of the raw earth, whose carbon footprint is unbeatable, the material infinitely reusable, without emission of pollutants or creation of waste. It is a fundamental subject for the designers and builders of this project who wanted to demonstrate the real and structural capacities of raw earth, which does not require reinforcement by "stabilization" or support legs. Of great interest for the raw earth sector and more generally the artisanal sector in the noble sense of the term, facing the increasingly productivist economy of construction in France, their commitment, their passion and their philanthropy have gone beyond the understanding. It was vital for them to make these arches of loadbearing facades in raw earth, without any external binder to stabilize it, as it had been imagined with the architect, from the competition phase. This project was also carried out in close collaboration with the researchers Antonin Fabbri (LTDS laboratory of ENTP) and Jean-Claude Morel (University of Coventry) for the scientific approach.
Construction is now one of the areas that contributes the most to the generation of significant waste in Europe, including a large amount of soil. It is Nicolas Meunier, director of the company Le Pisé, who resuscitated this centuries-old material that he has now mastered for several years. "My encounter with earth as a building material took place in Mali, and when I returned to France in 1984, I decided to continue" shares one of the rare craftsmen in France to use pisé. This entrepreneur created a mobile machine capable of delivering mud blocks up to 2.5 tonnes. Installed directly on the site, this tool allows the raw material to be mixed and then compacted into bunk beds to form the blocks. To achieve the building, 280 blocks were needed, or 610 m3 of earth.
Such a project and challenge could only be realized thanks to a hard core of designers associated with very competent craft companies, in love with a job well done, constituting a united team, with strong cohesion and trust between partners.
Project managers : Clément Vergely architectes Diener&Diener Architekten
Awarding authority : Ogic
Structural design office : Batiserf (conception et études d’exécution, dossier d’ATEx)
Masonry company : Construction en Pisé
Carpenter : Charpentes Nugues
Researchers and Laboratories : Laboratoire LTDS de l’ENTPE, avec les chercheurs Antonin Fabbri et Jean-Claude Morel (Université de Coventry)
The construction domain requires a significant amount of energy to maintain comfortable temperatures inside buildings, whether for heating or cooling. The advantage of raw earth is that it is a porous material, poorly conductor, that used in thick walls, retains both heat and freshness. The properties of the used material, pisé, allow to regulate the temperature in a natural way as well as the hygrometry. So, this building does not need added thermal isolation but only natural ventilation.
This R + 2 office building, with 32x14m area of ground occupied, also has a green roof terrace accessible to users, with lawns and flowers: a real outdoor space to improve the quality of life at work and form a lung in the heart of the small island.
© Batiserf
The total height of the rammed earth facades, from the top of the stone cover to the base of the massive stone piers, is 11m high. The concern for sustainability was also an important element of this project. The sharp edges along the lower surface of the arches are bevelled, chamfered or rounded, with varying width along the lower surface. This, in order to avoid splinters along the sharp edges, which could possibly be caused during the construction site or during the life of the structure; as well as to reduce mechanical erosion as much as possible due to the climatic stresses of the wind combined with water runoff on the facade in the event of driving rain. The bevels adopted in response to this constraint are an integral part of the architectural style of the facades.
The architecture of this building therefore regains the constructive quality of old buildings with the choice of using a raw material, which is raw earth. A challenge for designer architects, but above all for the design office, Batiserf. Knowing their job, they will calculate, develop different solutions and justify every detail of the structure. This is how, after a long fight with the various stakeholders, who are sometimes skeptical, they will succeed in moving the project from "inconceivable" to "achievable" and then built. "Only remarkable experts could calculate that pillars of raw earth of section 1.40 m by 0.80 m, would be sufficient to support the walls 11 m high, the two floors, and the green roof terrace", says Nicolas Meunier.
The company "Charpentes Nugues" produced all the floors in interface with the pisé facades and in close collaboration with the pisé company. The structure of the building is indeed an inseparable whole which has been designed and justified by Batiserf, in a comprehensive and coherent manner, each material being used in the right place, according to its properties (capacities and limits) by taking advantage of their respective qualities.
The intrinsic debates and obstacles were numerous and led to an execution study mission accompanied by the establishment of the ATEx file, in close collaboration with the rammed earth company throughout the project site. “We had to characterize this material and justify its hygrothermal and mechanical capacities to the control office, CSTB, as well as the insurance”, emphasizes Thibault VIALLETON, project manager for the Batiserf structure design office. There was a lack of confidence, both in the rammed earth technique with its artisanal implementation, but also in the absence of cement. The project is now completed, and everyone has been able to demonstrate that it is possible, "just" with raw earth without any additives. The natural use of this material is ecological because only soil without additives is fully recyclable without transformation. In addition, the rich French heritage of the use of rammed earth has demonstrated its capacities and its durability, even when used in seismic zones that have experienced significant tremors.
The Orangerie is a project that has aroused interest, advanced knowledge and created a dynamic.
Copyright © 2023