#Product Trends
New Civic Centre in Istres
An aesthetic and sustainable building
With 6,000 square metres of usable floor area, the new Civic Centre spans five storeys – public area, archives, municipal police force, two levels dedicated to administrative staff, councillors. This isn't just another standard office building. “All levels revolve around the atrium,” indicates Michel Vallière, lead architect of the contest winners. “Zenith lighting arrives through a glazed façade located on the uppermost level and illuminates the core of the building.” The ultimate purpose of this communal building is to “be the Town’s image bearer, for the citizens to be proud of and feel good when inside it.”
Interplay of light and reflections
To allow the site’s natural beauty to speak for itself, the building has deliberately been kept low-key, notably in its glazed frontages. This architectural stance lends “fluidity and transparency” to the construction according to mayor François Bernardini. “I didn't want the mass of the building to overwhelm the site,” adds Michel Vallière. “That’s why we opted from the outset for a building with lots of glazing, with glass that reacts to the light depending on the sun’s angle and merges into the pine wood background that wears a dark shade of green all year round.” The joinery colours are purposely chosen to be neutral. The curtain wall frameworks are fine and white on one side, blending in with the opal glass look, and charcoal grey on the other side to mix in with the reflections of the pine wood.
A sustainable building
Good looking and sustainable besides. Apart from any aesthetic merit, the new Civic Centre meets the criteria of the Mediterranean Sustainable Buildings (‘BDM label’) initiative. “Energy efficiency was a very clear objective in the specifications,” stresses Nicolas Davini, “and not just for PR reasons: it actually saves our ratepayers money!” There is a 60% energy saving compared with buildings of the same volume that do not have this label. In the construction phase, an environmental specialist scanned all the existing techniques then monitored the conformity of the job with respect to the BDM label.
Three environmental peculiarities were taken advantage of. First of all, there is a Provençal well with 2.5 km of underground galleries located beneath the forecourt. This arrangement enables fresh air to be blown into the building by fans. Next, three boreholes use water from the lake as the input to a geothermal system. Lastly, solar heating panels produce the building’s hot water.
Double-skin curtain walls
The building is shrouded with a double-skin curtain wall using the Tanagra® and Toundra® ranges from Profils Systèmes, with thermal ventilation. The air flow circulating between the two skins creates a buffer between outdoor and indoor temperatures. The air conditioning system plays these air masses against each other depending on the demand for extra cooling in the premises. The construction work was a real challenge. “We had never made a curtain wall as big as 100m x 20m before,” says Philippe Cambon, general manager of Istres-based manufacturing & outfitting company Sam. “We set up a drawing office for this job, with the recruitment of a draughtsman and a design engineer.”
Project manager Christophe Avantin found himself with the delicate mission of preventing overheating. “The temperature rise inside the breathing glazing must not exceed the planned value. We gave temperature imperatives for the forming of openings at the level of the louvres to ensure the curtain could breath. We did not want to run the risk of thermal breakage on the inside.” Finding the right material profile was a “complex matter, taking into account the thermal factor and the shadow region created by reflections from the pine wood”.
Usable floor area : 6125 m2
Total cost : 20 M€
Main Contractor : Atrium Architects – Istres
Contracting authority : SAN Ouest Provence (Bouches-du-rhône dept. - France)
Aluminium joinery work : SAM – Istres
Ranges : Profils Systemes Tanagra® double-skin curtain wall & Toundra® doors &windows
Photos & illustrations : Richard Sprang, Atrium Architectes
