"Lebensart" (German for way of life) is what the residents of a new apartment building in Rotenburg an der Wümme have called their association. The approach of founding an association and thus jointly financing and operating the house is only one of the innovative approaches of the entire project. The building's energy concept is also state-of-the-art and has been developed with a view to the standards required in the future. After all, the energy requirements of the building with its 3,000 square metres of usable space are 40 per cent below the specifications required by the German KfW Bank for a new building. In addition, there is another plus: a battery for storing electricity.
Increased self-consumption
The focus is on the heating system. That is taken over by a heat pump with an output of 30 kilowatts. Additionally there is heat recovery from the ventilation system. Both heat sources are sufficient to completely heat the entire building even on cold winter days. Both systems are powered by solar electricity produced directly on site on the roof of the building. The advantage: because the heat pump uses the solar power directly, the proportion of self-consumption goes up. But in order to use even more solar power on site, a solar storage system from Powertrust was installed in the basement.
34 kilowatt hours of storage
The Bremen-based manufacturer does not rely on the lithium-ion battery cells that are now commonplace, but uses lead crystal technology instead. The central argument for this is that the recycling rate is almost 100 per cent. "This was a very important selection criterion for us," is how Stefan Bruns, who played a key role in developing the project, explains the choice of the power storage unit. "Sharing and conserving resources is part of the philosophy of Lebensart."
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Combining tenant electricity with electric mobility
Regardless of the technology used, the storage unit does what a system of this kind is normally supposed to do: It temporarily stores excess solar power. This can then be consumed in the building during times when the sun is not shining. In total, it provides a capacity of 34 kilowatt hours for electricity from the photovoltaic system, which has an output of 35 kilowatts.
Covering performance requirements
This is sufficient to cover the required maximum output of 16 kilowatts of power that the building requires. The specification: The solar system must be able to deliver this maximum output in cooperation with the storage system for at least half an hour. For this reason, the battery was dimensioned so that it can feed 16 kilowatts of electricity into the household power supply system. With a capacity of 34 kilowatt hours, it also provides enough energy to deliver this power for the required period of time. (su/mfo)
