Vienna Twenty-two


CO2 neutral energy concept for urban development in Vienna 

In Vienna, a new urban area “VIENNA TWENTYTWO” arises. Experts from our contacting and building technology companies designed, planned, and realized this project in close cooperation. Fossil fuels had to be avoided, without compromising on comfort. We invest in the technical installations and supply 100% CO2 neutral heating and cooling for the next 23 years.  


Key figures : 

  1. Total multipurpose floor space: approx. 116.500 m² 

  1. 6 buildings up to a height of 155 m 

  1. 100% CO2 neutral heating and cooling supply 

  1. Contractual period: 23 years 


Problematisation and customer issues :


Two real estate developers planned this high-end project of urban multipurpose buildings including offices, a hotel, and apartments. We won the heating and cooling supply tender with an innovative concept of a circulatory network system (CNS) based on heating and cooling recovery. As a partner we optimized the energy delivery concept and invested in the installations. Furthermore, we will take care of the planning (including the handling of subsidies and approvals) and implementation. Finally, we will supply the heating and cooling required throughout the contractual period.  


Our response :

CO2 neutral energy concept for urban development 


The energy supply concept covers the heating demand of around 7.7 MW and a cooling demand of around 5 MW.  


The heat pumps use thermal heat from wells and geothermal energy and are powered by 100% renewable electricity. During winter, the CNS extracts thermal energy from the exhaust air and heats the buildings. In summer, the CNS works the other way around and cools the fresh air. Excess heat and cold are stored in various buffer tanks, i.e. our innovative solutions also uses the water in the sprinkler basins.  


Each apartment, office and hotel room can be heated and cooled individually. The floor heating and ceiling cooling in all rooms ensure highest comfort.  


Mobilised expertise :


Our experts were involved in the project development since 2014. We supported throughout the entire development process and after commissioning we ensure a smooth and 100% CO2 neutral heating and cooling supply. 


Results : 


  • 100% CO2 neutral heating and cooling delivery 
  • Highly energy efficient 
  • Highest comfort standards for the users 
  • Sustainable use of waste heat and localized energy sources  
  • Use of the most environmentally friendly and non-flammable refrigerants  
  • No technical devices (heat exchangers) on the building roof  
  • One point of contact for the customer 
  • ENGIE invests in the technical installation 
  • Long-term guaranteed supply of heat and cooling