La queue du lézard | Rue Royale Architectes

Experimenting with the active strip concept At the core of the urban renewal project for the Mireuil district of La Rochelle, “La Queue du Lézard” (“The Lizard’s Tail”) is a complex of local community amenities which is part of a plan proposed by ANRU (the French National Agency for Urban Renewal) developed together with landscape designers from the In Situ firm. A community centre, city sports grounds and a games library are grouped together in a 200 m long narrow strip made up of alternating built elements and voids. The daring, deliberately marked architectural style is integrated into the urban planning of large housing complexes. It is a cross-cutting place that provides functions, activities and images for the future neighbourhood. This social, political and committed project is the result of long process of joint consultation between local residents, elected representatives, technicians, staff and designers. It is designed according to the principle of generic architecture, constructed around a concrete spinal cord that contains all the technical and services areas, a glue-laminated skeleton and a skin of Douglas Pine. This overall architectural expression, which allowed programmes to be adjusted during the concept definition stage, now presents a general view in which solids and voids blend into each other. This design method and its capacities for flexibility earned the project the nickname of the “lizard’s tail”. Urban bonds Experimenting with the active strip concept A warm heart for the community centre Integrating environmental design for a Low Consumption Building project Urban bonds The project is located in a district whose urban development, typical of large housing complexes, is based on the planning principles of the 1960s. Based on a free open plan, it takes its coherence from its composition on a strictly right-angled grid. The space freed by the various demolitions made it possible to reorganise the public spaces, to accommodate new buildings and to assert the opening of the old Châteaux d’Eau neighbourhood onto Mireuil. The building fits naturally into this urban layout and is stretched in the form of a long volume of wood, from East to West, from the church on Avenue des Grandes Varennes to Rue de la Résistance. It runs along Passage des Ecoles and opens onto the square while being served by the street. From the viewpoint of form, the idea is to preserve a strictly horizontal building on a sloping site. This asserted horizontality gives coherence and legitimacy to this new programme in its confrontation with the scale of the site. This urban bonding, which takes places physically within the time required for rebuilding the city within itself, also forms a social bond in people’s minds and mentalities. The choice of generic architecture gives real strength to the scheme and allows it to accommodate the different programmes in a unified, coherent whole. It is the fine quality of the architectonic elements, the use of high-quality materials, and the play with light and sun that make it so varied and interesting. Construction started with the community centre, the city sports ground and a part of the children’s play areas (which were officially opened in 2012). The games library, which is currently being built, will complete the first phase of construction of the wooden animal in the summer of 2014. The City of La Rochelle is currently looking into the programme for the “Tête” [Head] that will be the finishing touch to the scheme. Experimenting with the active strip concept The community centre, located in the core of the scheme, makes use of the natural slope to organise itself in half-storeys. A concrete “spinal column” contains all vertical circulation routes, sanitary accommodation and building services areas. The roof contains a continuous services plenum covered with metal gratings that also cover the vertical ends. The adjacent roofs are planted and not accessible, but they are visible from neighbouring buildings. Glue-laminated timber portal half-frames, placed on a regular 2.70 m grid, form two spacious simple roofed structures – one on each side of this backbone – where all the scheme’s high-quality spaces are located. The envelope consists of a timber framework façade covered with Douglas Pine weatherboards, placed vertically and horizontally in alternation. These elevations appear to be held in place by vertical “props” that dance along the façades. These “props” consist of galvanised steel T-section stanchions, delicately faced with stabilised timber. On the south façade, the “props” are detached from the façade and support brise-soleil sun-breaks. Their positions are calculated to completely stop sunshine in the summer and to allow it freely into the rooms in winter. The games library is designed according to the same architectural and technical principle. It is currently being built as a second phase of construction. Originally located in the old city of La Rochelle, its siting in the Mireuil district gives it a new direction and increases its complementarity with the community centre’s activities. The games library is on one single floor level, with a public entrance on Avenue des Grandes Varennes, placed symbolically opposite the church entrance. The games room occupies the entire South wing open onto the central public spaces. It has a reserved external garden on the West, adjacent to the public play gardens. The building will be completed during the summer of 2014. A warm heart for the community centre Special attention was paid to the community centre’s reception area. Accessible from Place des Palabres on the South, it provides easy, safe access. Its central position allows easy access to all activities, and the large transparent glazed areas allow monitoring of circulation flows and of people. The reception lobby, with its warm, welcoming red colour, sets the tone for the whole scheme. This warm atmosphere is enhanced by the widespread use of wood (for the structure, internal finishes, and false ceilings), the large transparent areas and the omnipresent natural daylighting. Located on the three half-storeys, it has view of the entire building. The general organisation includes a very large space called the Agora on the West, which can be used completely separately or even rented for a token fee for private activities. It is entirely self-contained in terms of sanitary accommodation, eating facilities, access, etc. On each side of the active strip, there are rooms of different sizes, for offices or workshops. The simultaneous views of both sides of the building create a reassuring atmosphere and provide a permanent view of the surrounding city. On the other hand, the play of brise-soleil sun-breaks provide great privacy from the outside for users, who can see without being seen. Integrating environmental design for a Low Consumption Building project Certain fundamental principles of environmental design were applied: - a “bioclimatic” architectural concept based on compact buildings, ideally oriented in relation to the sun’s path. - a part of the structure is in concrete to give the building the required thermal inertia. There is also a glue-laminated timber structural framework. The external facings are in forested wood, such as pine. - thermal insulation is reinforced to limit heating needs. The choice of external insulation decreases thermal amplitudes between day and night, and between winter and summer. Special attention is paid to the building’s airtightness. Heat losses are limited, particularly by providing air-locks in all cases. - the spaces and openings are designed to limit heat losses and overheating as follows: On the south, large glazed wall openings are protected by canopies (which are adjusted to allow in the winter sun and to completely stop sunshine in the summer) and dense vegetation. On the north, glazed wall openings are reduced. On the east and west façades, the openings are fitted with external fabric blinds. - for summer comfort, the principle of natural ventilation is applied. On façades, users have access to opening parts. - sedum type roof planting increases the retention of rainwater, attenuates thermal shocks, and presents an aesthetically-pleasing “fifth façade” to neighbouring residents. - from the energy viewpoint, the spaces are highly insulated to reduce static heat losses. To counteract dynamic heat losses, the premises are ventilated by high-recovery (80%) double-flow units, with a thermal management system of the Trend type. - the buildings are connected to the existing heating system. Large rooms have floor heating (any overheating due to solar gain or to sudden variations in external temperature is limited by the low emission of the heating floor). - sanitary hot water is heated by hot water heating cylinders and solar panels (except for the games library). - in order to improve the energy balance and reduce internal heat gains, the lighting system makes the best possible use of natural daylighting with the installation of light detectors and the use of LED lighting.