| Abstract |
The majority of renewable energy sources have natural transient fluctuations in supplying energy. The increasing exploitation of these renewable energy sources for generating and supplying thermal energy thus requires flexible distribution systems of consumers, e.g. city quarters or, on smaller scale, buildings. Vice versa, it is interesting how transient changes in the energy demand of a consumer affect a baseload energy source. This can be adressed by dynamic simulation of the thermal energy demand of a consumer on a flexible timescale. For geothermal direct-heat supply using borehole heat exchangers (BHEs), such dynamic simulations can be used for modeling the thermal response of the subsurface to the demand of a specifically defined consumer. Usually, BHE field simulations use estimated average values for the energy demand as model input parameter. We present results of BHE field simulations, where the prescribed energy demand itself is the result of a Building Performance Simulation (BPS). For this, we use TEASER (Tool for Energy Analysis and Simulation for Efficient Retrofit), an open framework for urban energy modeling of building stocks. With predefined parameters, such as year of construction, net lease area, or number of floors, TEASER models the thermal power demand of a building based on outdoor temperature records. Based on the thermal power curves provided by TEASER, we simulate the performance of a three dimensional BHE-field in an urban area called Neu-Teveren. Neu-Teveren is a settlement built in the 1950s near the city of Geilenkirchen, in the lower Rhine embayment in Germany. For increasing their energy efficiency, the city intends to retrofit the buildings in the settlement. Our simulation results based on multi-year outdoor temperature records show that a layout with one borehole heat exchanger per building can be efficiently operated over a time frame of 15 years. Due to northward groundwater flow, thermal plumes of reduced temperatures develop at each BHE, showing that BHEs in the southern part of the model affect their northern neighbors. Changing the layout of the BHE-field significantly reduces influence of BHEs among one another, and thus increases the performance of the BHE-field. Furthermore, the preceding simulation of the buildings’ thermal power demands allows for evaluating the influence of the building state (old vs. retrofit vs. new) on the long-term BHE field performance. For instance, our simulations show that the cooling effect of the BHEs in the subsurface is about 3 K lower for retrofitted buildings. |