The "Staatliche Vermögens- und Hochbauverwaltung" is responsbile for all services relating to the administration of the property and building construction projects of of the Federal State of Baden-Württemberg. As experts in organising building projects they have also been responsible for the erection of the new ministry. The owner of the building is the Baden-Württemberg Stiftung GmbH. The Federal State of Baden-Württemberg has rent the house.
The energy efficiency requirements for the building which have to be met are very high. A maximum total primary energy demand of 120 kWh/m²a and a maximum heating energy demand of 30 kWh/m²a is required. A thermally optimised building envelope and modern, energy-efficient process equipment are applied to meet these requirements.
The innovative heating and cooling concept uses the municipal wastewater from the sewer Nesenbach canal as an energy source. The Nesenbach canal is one of the most important main sewers in Stuttgart with a flow of 170 l/sec under dry weather conditions. Under storm conditions, the flow rate can suddenly rise to several cubic metres per second. We carefully reviewed the edge conditions and after a number of meetings we presented our concept for heating and cooling with wastewater which was further optimised in the course of time. The basis of our concept is once more the HUBER ThermWin® system which has been installed in many successful projects already.
Two RoWin® Heat Exchangers size 8 and three heat pumps ensure that the ministry staff can work in a comfortable climate on every winter and summer day. To achieve this, up to 420 kW thermal energy is extracted from the wastewater and, through the use of heat pumps, about 530 kW of energy is delivered to the building. A district heating connection ensures the supply during peak load periods and serves as a redundancy system. Due to the use of favourable and high-efficiciency primary energy factors – district heat and heat from wastewater – the consumption of primary energy for heating can be reduced to below 30 kWh/m²a, which is equivalent to an energy consumption of 3 l fuel oil per year and square metre. A low temperature heating system is used to distribute the heat energy inside the building. To cover the basic heat load the heat is delivered to the offices via concrete core activation. Water-carrying pipelines running in the concrete ceilings and floors are used as heat and cold storage facilities. The concrete core activation system is also used for cooling during summer: About up to 600 kW heat are extracted from the building and 730 kW given off to the wastewater flow by means of the heat pumps. Due to the large effective surfaces a very pleasant indoor climate can be achieved with low temperature differences even on hot summer days. As the building can be heated with regenerative energy to a large extent it provides maximum comfortableness for the users at minimum energy costs and with maximum energy efficiency.