Congress Center of The Haute Saintonge | Tetrarc

Architect urbanist landscape designer - TETRARC
Architect project director - Michel Bertreux & Daniel Caud
Project manager - Rémi Tymen
Project assistant - Timothé Naux, Matthieu Blanche, Silvia Fioravanti, Maïlys Le Crom
Landscape - Louise Follin

First, the location was selected. A hole was excavated in the limestone, a cellar open to the sky, then a cave was created, a fissured limestone karst landscape, soft steps with worn treads, then the blinding light, and a return to the caves to marvel at the organ pipe stalactites...

The context
Combining business, cultural and leisure activities on a single site, the Haute Saintonge Congress Centre complements the range of existing facilities and represents a unique catalyst for dynamic development, both for the municipality and for all of Haute Saintonge. Created as a follow-up project to the “Les Antilles” aquatic complex which opened in 2002, a creation of Dutch architects Roelof and Nannie Hendricks, the Centre has to fulfil a number of requirements • express the dynamic nature of the region,
• underline the exceptional character of a major public facility,
• make use of its architectural style to represent the type of facility that is used (and will be used for decades to come) by managers of companies and organisations who choose to meet there, and
• acquire a distinctive personality of its own without rivalling the iconic image of Les Antilles While the Haute Saintonge Congress Centre has to fit into this perspective with visible longterm architectural quality, it is also important to root it firmly in its regional setting so that this spirit is conveyed to those who visit. Taking into account the sensitive features of the Val de Seugne landscape, we chose to design a building in the form of a monolith half-embedded in the valley landscape. To the south, the building’s emerging frontage is revealed as a light-filled circulation gallery, culminating around the theatre, the centrepiece of the composition.

Grand circulation gallery
Access is at a single point, on the south wall of the building complex, in order to create a sense that you are gently converging on the building. This general entrance controls access for all users. Performers enter at the rear of the building, where deliveries are also made. This flexible reception area is bathed in natural light. Here, you find the general reception desk, ticket office and bar. The circulation gallery puts the building’s visitors on show: at different times, it can be a comfortable area for seminar participants to converse, a space where conference discussions continue, a rendezvous for participants in festivities or events, or a foyer where in the interval, people discuss their first impressions of a concert or a play performed by renowned actors. All the facilities are directly connected to it.

Seminar space
L’espace séminaire organise ses salles sur 2 niveaux dans le secteur Ouest du bâtiment. Les salles de séminaire bénéficient d’une belle lumière de l’Ouest et du décor extérieur du front de talus recouvert d’une végétation rampante Large multifonction hall In “Event” or “Show” configuration, the large multifunction hall, the “Agora”, welcomes participants to a company convention, conference or congress, with comfortable folding tiered seating for 416. A stalls area for 160 people can be arranged facing a generous stage area. In “Reception” configuration, the mobile tiered seating is stored in the compartment provided for the purpose. The completely open floor of the hall offers the chance to host anything ranging from trade shows and organised events to event celebrations, dating forums or debates, as well as major commemorative or family ceremonies. Large curtains contribute to acoustic comfort while allowing users to conceal, if required, the opening to the excavated limestone steps that form a small open-air theatre.

Technical Areas
The multifunction hall is separated from the theatre auditorium by an acoustic buffer, formed on the ground floor by the catering and technical rooms, and on the higher level by the dressing rooms. This in-between space is also used on the ground floor for direct access to the two stages and the catering area via a loading dock making it easy to handle equipment and facilitating various tasks. Theatre auditorium The theatre auditorium, accommodating 500, offers elegant décor for top-quality shows. Waves of wood, cladding the walls and ceilings, form an exceptional design. This arrangement hides the catwalks and their lighting, and ensures that the acoustics can be finely adjusted, while still offering a décor that is at one with the opulence and comfort of the seating area. The care taken in welcoming the public extends to the fluidity of access to each level, and the largescale sculptural quality of the circulation gallery which brings people there. While still allowing billboards showing forthcoming events, a large opening to the south frames the landscape and floods the foyer with natural light.

Auditorium acoustics
The auditorium is designed as two distinct volumes: the stage and the audience area. The stage acoustics are designed to respond to different needs: affording good intelligibility for the spoken word or for singing, ensuring that musicians have good audio return in concerts using amplified instruments, including the entire audio spectrum, but also enabling a satisfactory listening experience for musicians in acoustic concerts. The stage walls are therefore clad in different materials whose function is to adjust reverberation within the space and to avoid certain phenomena such as echoes. The use of velour curtains of various sizes allows for regulation of the acoustics. The audience area is designed as an enveloping shell. Its asymmetrical shape, which appears to be a product of the architect’s unique imagination, is in fact carefully calculated to meet acoustic requirements: each element of the shell is designed so that sound coming from the stage is distributed over the whole of the tiered seating and control desk, and so that part of the acoustic energy returns to the stage. The material used to create the shape is rattan fixed to a wooden structure. A second material, plaster, is used with the rattan, and is applied to the non-visible surface to give the composite material the required properties in terms of acoustic reflection. The aim is that the shell’s walls reflect the sound waves, but in a uniform manner over a wide band of frequencies. Rattan alone would not enable this acoustic behaviour, hence the idea of using it in conjunction with a material bringing the mass and the effect of a flat surface. The principle used to fix the elements of the shell to the building’s structure is also carefully calculated: rigid enough not to create unwanted acoustic absorption (thus making the auditorium less “reactive”), the fixings must not transmit vibrations to the framework, and thus reduce acoustic insulation of the auditorium from the outside. To this end, fixing was carried out with threaded rods, which supply the necessary rigidity, but with an anti-vibration material introduced at the point where they attach to the framework. The result is highly satisfying, the reverberation balanced in both audience and stage areas. Despite relatively modest degrees of reverberation (of the order of 1.1 seconds), the auditorium gives a generous tone and good audio return between stage and audience.