In the municipality of Brütten (ZH), a multi-family home is being built that not only meets the Minergie P standard but also has no physical connection to the power grid. Energy storage will play a central role here. In addition to a power-to-gas system and fuel cells, a thermal seasonal storage system will also be implemented.
The idea is to use a seasonal storage system that can store heat using a heat pump and the excess yield from the photovoltaic system during the summer months. When the seasons change and winter comes around, the stored heat is then used both directly and also for hot water and heating via a heat pump.
Due to a lack of available space, the seasonal storage system will be located underneath the building (below the underground car park). Additionally, heat losses can also be minimized in this way thanks to the surrounding earth.
When it comes to determining the size of the seasonal storage system, there are a range of issues that need to be considered:
- Selection of the storage material (concrete, gravel, water, etc.)
- Geometric volume and shape of the storage system
- Type of heat transfer
Moreover, there is also the issue of how much heat will be lost when using this type of storage system. This can then be used to determine the total heat requirements (water required for hot water and heating, plus heat losses).
The Lucerne University of Applied Sciences and Arts will assist in answering these questions by evaluating materials and creating a transient, mathematical simulation model for determining the storage volume. Various material combinations and geometric dimensions can then be specified as input parameters, thus enabling the design of a seasonal storage system with an optimal geometry (volume and dimensions).