The city hall in the German city of Freiburg was awarded the Climate Positive rating by the German Sustainable Building Council (Deutsche Gesellschaft für Nachhaltiges Bauen, DGNB e.V.) on October 8, 2019 at the EXPO REAL trade fair in Munich, Germany.Drees & Sommer was responsible for the integrated energy concept, the General Technical Planning and for CO2 accounting following the completion.
The German Sustainable Building Council’s award confirms that the building is operated according to its assessment standards for climate-neutral buildings and locations. This means that, during operation, the building eases the environmental burden and has a positive impact on the environment. The data analysis shows that the sustainable generation of energy, offset against the actual consumption by the building, results in no additional CO2 emissions. Indeed the building cuts back almost 10 tons of CO2 per year caused by other emitters. It therefore has a climate-positive effect and, including its own consumption, it has a positive CO2 footprint comparable to that of 50 trees.
Dr. Michael Bauer, Partner at Drees & Sommer SE, commented: ‘The climate-positive rating from the German Sustainable Building Council for Freiburg’s city hall clearly confirms the innovativeness of the project and the implemented energy and sustainability concept. It is an outstanding example of how, with innovative approaches and a little courage, building projects can make a positive contribution to climate action. To strengthen the impact that this building is making, other builders and property developers should follow this example.’ The project management and real estate consulting company was the general technical planner for the showcase project, and was responsible for the energy design, energy management, building physics, building technology, façade engineering, and CO2 accounting.
The city hall in the Stühlinger district of Freiburg, designed and realized by ingenhoven architects and Drees & Sommer, is the first public net plus energy building of this type and use in the world. With their energy concept, the experts ensured that the building generates more energy than it uses, with the surplus energy being fed into the city’s electricity grid. The primary energy requirement for heating, cooling, ventilation and water heating is only around 55 kilowatt-hours per square meter per year – only 40 percent of the primary energy requirement of comparable modern office buildings. The thermal energy for heating and cooling needed by the building is generated by suction and injection wells with a heat pump and solar thermal energy. The electrical energy is generated by a photovoltaic system on the rooftop and on the façade. The mechanical ventilation has a highly efficient heat recovery system.
The climate positive rating of the DGNB is valid for one year. In order to continue to be awarded a climate positive rating, the owners must renew their balance sheet data for the following year.