TU Wien’s Plus-Energie-Bürohochhaus: A plus-energy high-rise

Public nZEB buildings case study
Building type
Public University
Project type

World’s first energy-plus office tower, Austria’s largest building-integrated photovoltaic system © Schöberl & Pöll GmbH


The Vienna University of Technology (TU Wien), founded in 1815,  is a prestigious public research university in Austria reputed for engineering, natural sciences, and architecture.

On the university campus lies an eleven-storey 1970s tower block, with a total floor area of 15,500 square meters. As part of the “TU University 2015” project, the building was refurbished and transformed  into a modern, energy-efficient building. The building was redesigned to produce more energy than it consumes, resulting in a surplus of energy that can be supplied to the grid.

How was this building procured?

The Austrian Federal Real Estate Company (Bundesimmobiliengesellschaft) owns the building and rents it to the university. When it was decided that the building would be renovated as part of a lighthouse project to meet ambitious energy-efficiency standards, a consortium of 20 partners from research and industry came together to develop the concept. The procurement of the renovation works followed a Public Procurement Promoting Innovation (PPPI)  process. Procuring the Plus-Energie-Bürohochhaus renovation works represented a 26 million euros investment, of which 65% was innovation-related. Of this, 23 million euros were spent on building renovations and 3 million euros on the interior fittings.

What are the key nZEB features?

The Plus-Energie Bürohochhaus was designed to consume minimal amounts of energy while generating renewable energy to cover its energy demands. The building’s key features include:

  • Triple-glazed windows with sun protection and insulation;
  • An air-tight building envelope;
  • Use of renewable energy sources, including photovoltaics and geothermal energy;
  • Use of energy-efficient building technologies, such as LED lighting, heat recovery systems and energy recovery from elevators;
  • Intelligent building automation system for efficient energy management;
  • The building’s design also incorporates flexibility and adaptability to meet the changing needs of occupants while ensuring comfort and productivity.

Did the project have an impact on skills?

This renovation project relied on interdisciplinary collaboration, integrated planning, and built on existing innovation. As a lighthouse project, the building showcases the scientific and technical abilities of the TU Wien and of its project partners. The skills and tools acquired during the renovation have been used for the renovation of the other buildings on the campus. The project’s success has also inspired other construction projects in the city to adopt energy-efficient and sustainable building practices, leading to a broader adoption of nZEBs and contributing to Austria’s national energy and climate goals.

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