The renovation of the Uhland School in Stuttgart, within the scope of the research initiative “Energy-efficient Schools – Eneff: Schools”, was aimed at raising the energy efficiency and implementing an innovative overall energy master plan. One element was the use of vacuum insulation between the ground floor and the soil and in the roof. Triple-glazed windows were also installed. These measures enabled more than an 80% reduction of heat loss through the shell of the building.

The building’s energy supply comes from solar power and geothermal heat. The heat is supplied by four brine/water heat pumps using more than 50 geothermal probes at a depth of 90 metres under the ground, complemented by a low-temperature surface heating system. The heat pumps and the building’s technical equipment as well as the ventilation systems and the lighting are powered by solar energy supplied by photovoltaic systems on the roof. Since electricity is needed in the daytime during school hours, the solar energy supplied by the PV systems can be directly accessed.

In summer, the building is aired manually by opening the windows, while motors on the window frames enable cross-venting during the night to prevent the classrooms from overheating. In winter, individual room ventilation devices, as required, are used to recover the heat. The devices used in the IT and service areas have a particularly high level of energy efficiency.

In the first year of operation, the plus-energy building had an electricity surplus of 42 MW. As of November 2018, a two-year comprehensive monitoring period will begin, including a survey of pupils and teachers, aimed at showing whether the technology used is really working efficiently or whether readjustments are needed. The users’ level of comfort will be assessed with a view to making possible improvements and modifications. The researchers of the University of Stuttgart and the Office for Environmental Protection of the state capital Stuttgart will evaluate the data, which will automatically be recorded by the sensor technology that has already been installed.