Building in existing structures: ZÜBLIN celebrates the opening of the new Z2 Group building in Stuttgart

ZÜBLIN is sending out a strong signal for more sustainability in the construction industry with the opening of the completely refurbished Z2 Group building. The striking six-storey office building with the characteristic rounded façade bands on the ZÜBLIN campus has undergone extensive energy-efficient and sustainable refurbishment over the past 18 months.  

“With the refurbishment of Z2, we are delighted to have realized a forward-looking project for resource-conserving and sustainable construction in existing buildings. We are thus reducing our CO2 emissions in building operations. It is a further step towards our ambitious goal of achieving climate neutrality as the STRABAG Group by 2040,” explains Jörg Rösler, Member of the Executive Board of STRABAG SE. 

Saving energy, protecting the climate 
For the Z2 project, the planners used generative design to parametrically record the existing building and optimize its energy efficiency. With the help of GIS data and escape route plans, important parameters such as air volumes and heating and cooling loads were calculated in order to create a sustainable building. 

The ZÜBLIN team has upgraded the energy efficiency of the entire building envelope, i.e. the roof, the façade and the ceiling to the underground parking garage. Heat pumps now take over the heating and cooling of the building. A photovoltaic system on the roof provides the building with its own renewable electricity. It is supplemented by solar modules on the façade and an innovative photovoltaic fence as fall protection on the roof. Generated energy that is not needed immediately is temporarily stored in an energy storage unit.  

The existing building dates back to 2002, but the technical innovations of recent years have opened up numerous opportunities to make the building significantly more energy-efficient. The STRABAG Group is making targeted use of these opportunities in line with its sustainability strategy. By retaining the building shell, the existing access cores with the stairs and elevators and a large part of the sanitary facilities, the Z2 is a prime example of resource-saving construction in existing buildings. The aluminum strips of the façade were dismantled, refurbished and reused. Reusable and reusable materials and components that are no longer in use were passed on by the external platform Concular. 

Cooling with living green 
Wherever possible, ZÜBLIN has incorporated recyclable and cradle2cradle certified materials and components. 25 percent of the new materials come from recycled or reused sources. At least 85 percent of the wood used comes from certified sustainable forestry and at least 50 percent of the concrete, earthworks and plant substrates used are made from recycled materials. A prototype of reusable drywalls was used for the room layout. The green façade on the first floor provides sun protection in summer and improves the microclimate.  

There are 48 charging points for electric vehicles in the first basement level of the underground car park. The infrastructure for a second expansion phase with a further 48 charging points has been prepared. This means that every second car parking space is equipped with a charging point. Two lockable bicycle charging cabinets with space for a total of 18 bicycle batteries have also been installed. 

Use of the latest construction technology 
ZÜBLIN relied on state-of-the-art technology for the construction work, for which around 25 million euros were invested. A digital cycle control board enabled everyone involved to track the construction progress at all times and thus better coordinate their work processes. 

A mobile 3D concrete printer, which can flexibly print elements, was used for the interior work as part of a pilot project. This not only makes construction projects more efficient, but also more sustainable thanks to the use of new materials and a special lightweight construction method in 3D concrete printing.  

So it is no wonder that not only was the construction process monitored by the German Sustainable Building Council (DGNB), but the finished building now will also get a platinum certificate for sustainable buildings from the DGNB as well as the QNG premium award. In this context, the high degree of reused building components, the resource-saving processing of new building elements and the greatest possible use of emission-avoiding technologies in the building fabric and for future building operation should be emphasized. For ZÜBLIN employees, this has created attractive and flexible workplaces with outstanding technological equipment in an appealing architectural environment.