© Roland Halbe

Bursting with Energy

Introducing campoV – Germany’s first student residence designed as a so-called energy-plus building

Hearing that a student dormitary is, in a manner of speaking, bursting with energy is not likely to raise eyebrows. But people might take a closer look if they hear it’s literally generating energy. This is the case with campoV, a student dorm in the Vaihingen district of Stuttgart and the first in Germany to be built as a energy-plus building. In other words, it was designed to generate more energy than it consumes. Planned and constructed by Wohnbau-Studio, a real estate development company based in Stuttgart, the project was supported during the planning and construction stages by the Steinbeis Innovation Center energieplus, which was tasked with overseeing the project from a scientific angle for three years.

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Spanning almost 3,000 square meters (roughly 33,000 sq ft), the 126 partially furnished residential units in downtown Vaihingen provide students with urgently required living quarters. In addition to a geothermal heat pump and a 140 kWp photovoltaic (PV) system on all roof areas, the building is also equipped with a 100 kWh lithium iron-phosphate storage system ­– a good basis for future developments in energy concepts, especially when it comes to micro-apartments. The ground underneath the building is being used to support the heat pump through low-temperature ground-source heat exchange.

“Space constrictions are quite usual with downtown developments, which is why roughly half of the fourteen geothermal probes under the building were drilled to a depth of 140 meters,” says Steinbeis Entrepreneur Dr.-Ing. Christian Kley, explaining one of the challenges of the project. Heat is extracted using a brine/water heat pump, which has been connected to a low-temperature underfloor heating system. This heat pump provides almost all of the thermal energy required to heat rooms in the building and supply hot water. For backup reasons, the buffer storage tanks in the building have also been fitted with electric heating elements. In the summer months, the combined underfloor heating and cooling system regulates the apartments’ temperature using passive cooling, which draws on geothermal probes and heat exchangers.

The challenges of surplus-energy standards

Once the building was completed and occupied, the experts at the energieplus Steinbeis Innovation Center (which also received public funding for the project) meticulously monitored the building over a 2.5-year period. This involved evaluating and analyzing energy consumption in the building, which was particularly important given strict requirements affecting energy-plus buildings.

An analysis of the energy required to run the building and the electricity used by occupants revealed that 83 to 89% of the electricity generated by the PV system was used, with solar energy covering around 35% of overall demand. These results mean that the building does not yet meet surplus-energy standards; the PV system will need to be expanded and the energy consumed by occupants must be reduced. “We’re keeping in close contact with the developer, even after completing our monitoring, and we’re working together to develop some innovative ideas to increase PV output,” explains Steinbeis project manager Leonie Nietfeld.

The efficiency of the electricity storage system in the building stands at around 80%. Intermediate storage of electricity generated during peak periods is working well. This energy can be used in the night, thus reducing the amount of grid electricity required and allowing peaks in demands on the public power grid to be flattened. Using heat pumps for heating purposes and hot water, in combination with large storage units, makes it possible to improve the efficiency of supplied heating.

Above all, monitoring the project proved to be helpful in highlighting one factor, namely that there are often differences between theory and practice. When the experts reviewed planning parameters, it was found that building occupants actually consumed much more electricity and hot water than expected. Building use, as well as the technology used by the students, was at a significantly higher level than previously experienced. In buildings with a high number of residents, such as student dormitories, the occupants clearly have a major influence on the cumulative energy balance – much more so than was initially assumed. The excess energy requirements compared to planned levels were largely due to the higher levels of consumption of the building occupants. Optimizations made to the technical systems were successful, however, such that they now run more efficiently.

Tracking energy consumption at a glance via smartphone

The recent pandemic also played a role in the spike in energy consumption of the building. For a long time, the majority of occupants stayed at home and only attended lectures online. In addition, it was not possible for the large number of international students to visit their families. Since the pandemic, the building owner and its operator have been working on a variety of concepts aimed at joining forces with residents to focus on energy use.

Energy issues are also now on the radar of people living in special types of accommodation, and these are being highlighted to campoV residents via a specially developed app, which was programmed by mondayVision, a Stuttgart hardware and software developer. “The app’s gradually taking on more and more features to help residents use energy more responsibly. Just some examples of those features are a plot of individual electricity and heating consumption, rankings in comparison to other residents, and even a link to see if the washing machines and dryers are free in the laundry room,” says Nietfeld. In addition, a number of contests were launched during the research project to reward particularly low levels of energy consumption or reward significant reductions compared to previous consumption levels. There were also events to share information with residents, and improvements were made to lighting in the building and hot water faucets.

Aside from all the challenges, in addition to acquiring new know-how when it comes to planning, constructing, and operating such a building, the experience gained from the research project showed that it is possible to prepare student dorms for future needs when it comes to climate neutrality. That said, it’s important to consider the fact that compared to other forms of residential buildings, consumption is particularly intensive due to the high occupancy levels. Values normally used to plan consumption rates according to floor space are only of limited relevance to this special type of building. This makes it important to introduce special measures in order to raise awareness among occupants and reduce consumption. The Steinbeis experts feel that more research is now needed, particularly when it comes to awareness regarding the consumption patterns of residents, when it comes to preparing functions and operating modes to be introduced as standard, and when it comes to improving market acceptance through presentations and PR.

For more information on the research project, see: https://tinyurl.com/2qxx9bu6


Leonie Nietfeld (author)
Scientific Assistant
Steinbeis Innovation Center: energieplus (Stuttgart)

Dr.-Ing. Christian Kley (author)
Steinbeis Entrepreneur
Steinbeis Innovation Center: energieplus (Stuttgart)