DETAILS DU PROJET
Administration building in Basel built with WICONA’s closed cavity system
Energy-efficient, ecological, aesthetic: With the new Office for Environment and Energy (German: Amt für Umwelt und Energie (AUE)), a showcase project for sustainable construction has been created in the centre of Basel. In addition to the innovative wood-concrete hybrid construction and the holistic energy concept, the WICONA closed cavity system made of recycled end-of-life aluminium integrated into the façade also contributes to the high environmental quality and compliance with the Minergie-A-ECO standard.
Energy efficiency, construction ecology and architecture combined
Since the existing AUE building no longer met current needs, the decision was made to construct a new building in the historic city centre of Basel. It was important that the new building for the authority enforcing energy-efficient construction projects in the canton of Basel-Stadt also served as a role model in terms of energy efficiency, construction ecology and architecture. The architectural firm jessenvollenweider architektur ag (Basel) planned an administrative building that meets all the requirements of future-orientated construction, while fitting into the listed context.
The eight-storey building was developed as a filigree skeleton construction with a timber frame. In combination with its concrete ceilings, this achieves a high heat storage capacity, which supports night cooling in summer. This principle of consistent room ventilation is just as much a part of the comprehensive energy concept as the high level of heat recovery, use of district heating, use of rainwater, high level of energy recovery via the façade and highly thermally insulated building envelope with the closed cavity system and associated optimal use of daylight. However, that’s not all, as architect Sven Kowalewsky pointed out.
“We used non-toxic and natural building materials, in order to meet the requirements of construction ecology. Component construction was also optimised in terms of grey energy.” Inside, the almost 80 employees find a friendly environment with modern furnishings. Open-plan offices with island workstations are complemented by flexible open-space areas. A conference room, a utility room and an archive room are located on five of the eight floors. There is a cafeteria with a small terrace on the top floor, and a visitor zone, among other things, on the ground floor next to the reception area.
Innovative façade solution with energy generation
As the central design element of the new building, which was planned entirely in the BIM process, the innovative façade solution is a real eye-catcher among the surrounding historical buildings. In order to completely cover the demand for operating energy from renewable sources, the architects planned photovoltaic modules for the opaque façade area on all sides of the building. These are equipped with highly efficient monocrystalline PERC cells and produce around 45,000 kWh of electricity per year.
A special fused glass was developed especially for the project, so as to be able to optimally integrate the design of the façade into the cityscape. Sven Kowalewsky explained that by integrating coloured dots that appear like cast-in glass beads, the dark base tone of the PV cells is broken up and overlaid with warm colour tones, providing a different perception depending on the viewpoint and lighting situation. Thus, the building sometimes comes across as a dark technical power plant, sometimes colourfully integrated into the context of the neighbouring sandstone buildings, and sometimes as a luminous glass house.
The closed cavity system for energy efficiency and user comfort
WICONA’s innovative WICTEC Modul air closed cavity system is integrated into the façade as a kind of a box window. In this special double-shell construction, the profile system accommodates the inner glazing and the outer frame of the impact pane. The glazing technology is designed to create a cavity that is sealed off from the environment. Monitored by a cloud-based monitoring system, conditioned air with minimal overpressure is introduced into this intermediate space. This prevents moisture from the exterior or interior from entering the cavity.
The sun protection designed as a Venetian blind solution also remains clean and protected within the cavity. It can be adjusted to suit the individual needs of the user, thanks to an intelligent control concept. This guarantees a pleasant room climate, optimum transparency, effective glare protection and maximum energy efficiency at all times.
As part of the ventilation concept, the building is cooled passively by means of narrow ventilation flaps integrated into the windows. These open automatically when it is cooler outside than inside. As a result, the closed cavity system reduces heat loss in winter and, in combination with the sun protection and automated night cooling, offers very good thermal protection in summer.
WICONA’s Project Manager, Marco Theisinger explained that the AUE project comes very close to the current physical construction limits for thermal insulation, total energy transmission and soundproofing. This way, the closed cavity façade offers maximum user comfort over its entire life cycle, with comparatively very low maintenance costs for the investor.
Recycled end-of-life aluminium for sustainable CO2 savings
The high sustainability requirements placed on the new building are also reflected in the material used for the closed cavity façade. The WICTEC Modul air profiles were made from Hydro CIRCAL end-of-life aluminium. This material was previously used in an aluminium product and therefore requires just 5% of the energy of primary aluminium during production.
Marco Leusciatti, Director of Hydro Building Systems Switzerland AG and responsible for the WICONA brand, was proud to report that Hydro CIRCAL has one of the lowest carbon footprints in the world, at just 2.3 kg of CO2 per 1 kg of aluminium. This is 4.5 times less than the global average for conventional primary aluminium and means that the façade solution makes a significant contribution towards optimising the ecological footprint.
Conclusion: The Office for Environment and Energy is a sustainable flagship project, showcasing a modern, energy-optimised and sustainable building in an inner-city location that blends harmoniously into the listed context of Basel.
