Nebout Estate Wine Cellar: an exemplary project using Activ'Home wood-straw walls

Located near a stream and backing onto the main road, the exterior space, viewed from above, is characterized by its wine glass shape. This low-energy building, facing due south, is distinguished not only by its form but above all by a design based on a collaborative model that notably utilizes Building Information Modeling (BIM) and a mix of exceptional, even bio-based, materials, such as the timber-frame and straw walls by Activ'Home…

A unifying reference point, co-created through BIM

For the construction of their future winery (a €1,8 million investment), the Nebout couple, owners of the estate, approached the TVMC association (Territoire Viticole du Massif Central), whose mission is to support winegrowers in the financial structuring of their projects. Impressed by the approach of Alice Architecture, an agency specializing in "out-of-the-box" projects, the association naturally turned to them for the commission. TVMC then led a collaborative design process involving clients, tradespeople, and the architect, with the pooling of skills through Building Information Modeling (BIM, or digital model) as the unifying element.

Moreover, for Charles Coulanjon, who also designed all the tools and materials: “Pooling skills from the outset brings enormous added value in optimizing costs. Initially, the project was limited to a rectangular building with cladding. Today, with the same budget, we were able to meet all of the client's needs. While there were quite a few technical debates prior to installation, particularly regarding reinforcement of the frames provided at the highest point of the building and the complexity of creating harmonious curves, collaborative co-engineering made it possible to find reassuring solutions for each stakeholder and ensure a controlled cost.”

A modern, low-energy building constructed with bio-based materials.

With a philosophy of using the right materials in the right places, the architect has always wanted to "prioritize the use of bio-based materials, limiting the use of concrete only where strictly necessary (here, for the foundations and slabs)." For the Nebout couple, owners of the estate: "This new building was born from a need for hospitality and comfort, but also from a broader reflection on how we wanted to build the future. We wanted a warm, functional space that reflected our work as winemakers. When we envisioned this new building, we wanted it to reflect our approach to working the vines: something sustainable, vibrant, and rooted in our land. Wood, straw, and stone seemed like the obvious choice. These are natural, local materials that breathe, provide excellent insulation, and make perfect sense for a farm and vineyard like ours. Straw is a simple, almost ancient material, but one that is now used with modern techniques." There's a kind of down-to-earth common sense in that: using what the land produces to build intelligently. This building isn't just a place to work or sell. It's also a way of showing that we can develop our farms while remaining true to our values: respect for the product, the landscape, energy, and future generations. In wine, we often talk about terroir. For us, the building is also part of that terroir: it must blend in naturally, be welcoming, warm, and convey something authentic to visitors.

The couple initially wanted to use straw from their own estate, "to complete the cycle"; however, as the practical conditions couldn't be fully met, the straw used in the Activ'Home walls comes from the nearby Limagne plain. This choice resulted in a sustainable building, perfectly aligned with their organic winemaking practices and their desire to create a festive space. With a total of 871m² ^of straw-bale walls (with a semi-load-bearing frame) laid in a rounded shape (using solid Provençal stone) on a 22m radius circle, this project exemplifies Activ'Home's expertise. It combines bio-based materials and efficiency with the full range of engineering and support skills, ultimately resulting in a healthy and exceptionally comfortable building.

According to the architect, "These bio-based materials guarantee thermal comfort and substantial energy savings, complemented by wood wool for interior acoustics. This winery construction project fully embodies my philosophy of 'using the right materials in the right places,' where simplicity and coherence meet timeless elegance."

He elaborated: “We thus created a highly efficient thermal envelope, and no calculations were needed to confirm it. It works. For me, it's self-evident, reinforced by the simple observation that as soon as the building was roofed, the tradespeople abandoned their temporary construction site offices to move into this new space. The thermal comfort was exceptional, even before the building was fully enclosed! Today, I maintain that the details of purely thermal calculations are of little importance compared to the final feeling of comfort. Straw is truly a material of exceptional quality. Simply compressing it gives it remarkable fire safety performance and makes it unattractive to rodents. And, of course, it possesses remarkable thermal characteristics. The climate change that began a few decades ago raises many questions in terms of thermal regulation, temperature comfort, and especially summer comfort. For us—architects, engineering firms, and other designers—this is a challenge that will be central to our concerns.” Current solutions exist but remain marginal, while the cost per square meter ^is extremely competitive! It is essential to work towards their widespread adoption. Wood and straw are undoubtedly materials of the future capable of largely addressing this issue. Together, our expertise and the quality of all these materials combine to achieve excellent construction with low energy consumption, creating comfortable, functional, and aesthetically pleasing workspaces and living spaces.

And Charles Coulanjon concluded: “This comprehensive construction method aims for energy self-sufficiency and is adaptable to any type of project without exception, from individual houses to industrial buildings. It's a first step towards the democratization of straw bale construction in all its forms. Proof of this is that we just delivered this winery for around €1000 per square meter ^, representing an additional cost of €200 per square meter ^compared to a traditional concrete block and concrete construction, for unparalleled comfort. Straw bale construction is indeed a material of the future, and I will do everything I can to contribute to its development.”

A curved facade made of timber-straw walls: precise panel layout and structural adaptation

The construction of this wine cellar is distinguished by its rounded façade, made of straw-wood walls arranged in a precise curve. The main challenge was to translate the building's circular geometry into simple, manageable, and material-efficient construction elements. To achieve this, a specific panel layout was implemented. The circular wall was divided into a series of 2,40-meter facets, corresponding to twice the standard width of the 1,20-meter straw-wood panels. This approach minimized waste and optimized panel usage. The building's diameter was then adjusted and validated so that the slight variation resulting from this faceted structure could be easily compensated for during construction. The project was thus based on a diameter of approximately 44 meters, allowing for straightforward adjustments at the midpoints of the facets.

A second challenge concerned the varying height of the walls. The roof, placed on this circular facade, incorporates a slope: the walls are therefore never exactly the same height, varying between 7 and 8 meters. To streamline manufacturing, the base of the walls was standardized at a height of 5,60 meters. This dimension corresponds to the assembly of two 2,80-meter-high panels, while maintaining their standard width of 1,20 meters. This solution made it possible to repeat the same construction principle along the entire length, before specifically treating the upper part of each wall with cladding adapted to the roof slope. Finally, given the significant height of the walls and their two-part composition, particular attention was paid to their stability. To prevent any hinge effect and ensure resistance to wind loads, a vertical glulam timber element was integrated along the entire height of the walls, in consultation with the structural engineering firm. This system ensures the structural continuity of the whole and follows the architectural curvature of the building without compromising the constructive performance of the wood-straw walls.

Activ'Home wood-straw walls

As a reminder, Activ'Home, acquired at the end of 2024 by Spurgin (the leader in precast concrete walls and panels), is the exclusive distributor of wood-straw construction modules produced using a short supply chain, based on the patented ECOSTRAUV® process. The company was awarded the Jury's Choice Award at the 2021 EnergySprong Awards and won the National Innovation Competition of the 2020 Grand Investment Plan. The Activ'Home wood-straw construction module serves as both a frame and insulation for walls, partitions, and floors (both upper and lower). These modules, compliant with RE2020 regulations and eligible for E+C- certification, are used in load-bearing walls up to two stories (R+2). Above two stories, they can be used as building envelopes and flooring on metal-framed structures. Indeed, their low weight (approximately 100 kg/m² ⁾ makes them ideally suited to this type of construction. It should be noted that buildings constructed with these Activ'Home modules are, by default, passive houses (with a thermal lag of up to 17 hours and R-values ​​up to 7,5 m².K/W) and are four times more energy-efficient than RT2012 compliant buildings. Annual energy consumption is thus less than 15 kWh/m², resulting in a negative carbon footprint (10 kg of carbon stored per m² ^of panels). Activ'Home has demonstrated the technical and environmental relevance of its product, combining bio-based materials, carbon storage, and exceptional thermal lag. Finally, while Activ'Home solutions (wood/straw walls and facades) offer exemplary performance in new construction, they are also an obvious choice for renovation projects, as they effectively protect existing building envelopes.