The rehabilitation and extension of the city hall aims to connect three very different buildings: one dating back to the 19th century and two others dating back to the 1970s. By adding a new reception structure and by improving the thermal performance and visual aspect of building envelopes, this project creates a new image of the city hall, in addition to a modern, open vision of administrative services.
The project’s different components all transmit a contemporary image of the city hall. The glass façades, stainless steel structure and mesh used for connecting elements have been designed as aspects of a new urban landmark that ensures the city is seen in a modern light. This approach is supported by a visual communication strategy featuring dramatic lighting. Light-emitting diodes, which can be used in many different configurations, illuminate the glass façade, the stainless steel shell and the water feature.
To enhance the site’s different architectural entities, low volumes have been created to link existing buildings. A stainless steel mesh covers all connecting and transitional elements, and is used to protect the lower floor of the glass façade. The structure suspended between the two 1970s buildings is a transitional zone where indoor and outdoor meeting rooms, rest areas, waiting rooms and loggias can easily be transformed for private or public use.
Developing Private Outdoor Areas
Small terraces are dotted around the buildings. In addition to being used by staff during breaks, they create openness and views to and from outdoor areas. The large terrace above the reception area – both mineral and vegetable – can be used for official ceremonies and weddings.
Highlighting Heritage Value
Today, the site is home to three buildings that were constructed using three completely different styles. One of our priorities was to portray a single, coherent establishment, while respecting the heritage value of the 19th-century building.
Consequently, the two modern buildings were given new metal/glass skins featuring screen-printed façades and stainless steel mesh covering connecting and transitional elements. The glass façade is set back from the historical façade. This respectful attitude to the older edifice also ensures direct sunlight is provided to all offices.
This approach highlights the autonomous nature of the new reception area, which is housed in an architectural structure that is stylistically different to all pre-existing buildings. Its curved shape and ethereal form absorbs and highlights the differences in surrounding buildings. It is another historical element in the existing composition and does not detract from the monumental nature of the adjacent building.
Creating a stainless steel shell
Made of stainless steel, its curved form creates an impression of softness, calling up images of work by the artist Anish Kapoor. The shell was fabricated and finished using techniques reminiscent of the city’s industrial and mechanical heritage. Inside, perforations in the shell’s envelope filter the light entering the building while still allowing visitors to enjoy views of urban areas. Outside, the shell seems to float on the water that surrounds it. This material does not need any maintenance or further treatment.
Installing a double-skin façade
The new skin is composed of a “breathable” screen-printed glass façade with built-in venetian blinds. Air enters vents at the base of the building. In winter and mid-season, it is captured and heated before being directed to the double-flow ventilation system where it in turn heats incoming air. In summer, air is released outside through roof vents. The system is managed by a computerised building management system, which also adjusts the position of venetian blinds in the façade and the double-flow ventilation system.
Special attention has been paid to using environmentally friendly techniques, including double-skin facades to trap pre-heated air and reduce the need for heating in winter and mid- season. Exterior walls are insulated using 20cm of insulating material on vertical surfaces. High performance double-glazed windows with argon gaps have been used. The main façade’s “breathable” windows have built-in venetian blinds. Source by Atelier Filippini.
Location: Illkirch-Graffenstaden, France
Architects: Atelier Filippini
Engineering Consultant: OTE Ingénierie
Environmental Engineering Consultant: OTELIO
Acoustics Expert: AKOUSTIK Ingénierie & Conseils
Construction Management: MP Conseil
Control Office: DEKRA
Safety and Health Protection Coordinator: ELYFEC
Accessibility Assistance Ca: ACCESSIBILITE & HANDICAP
Environmental Assistance Ca: QUALICONSULT
Nt Assistance Ca: AXXIP
Area: 2200 m2
Cost: € 5,300,000 VAT
Photographs: Christian Creutz