Performance Assessment of Heat Distribution Systems for Sensible Heat Storage in Building Thermal Mass

With the growing share of renewable non-dispatchable energy generation the challenge of matching electricity production and consumption arises. To facilitate balancing excess renewable electricity generation (i.e. at times of strong wind) the potential for thermal energy storage in buildings is analyzed within our project. As of today, pricing schemes for electricity in Germany and most other countries are either not time dependent at all or a lower price for electricity is only provided at night. Considering the rising share of renewable electricity generation, it is expected that dynamic electricity prices, driven by the actual availability and demand, will be introduced in the future creating demand for more storage capacities. The focus of this analysis is the evaluation of energy storage in buildings’ thermal mass, comparing conventional radiator heating with concrete core activation (CCA) as heat distribution system. Therefore, within an accurately monitored room at our research center a field study was performed and the results were compared to simulation outcomes of a thermal model for the same room. Since the behavior of the simulation model proves to be close to the thermal behavior of the real room, the model is then used to simulate a scenario for activation of the building’s thermal mass according to a signal describing the availability of renewables. For both systems a three-hour overheating phase allowed to postpone further heating demand in winter by more than eight hours. The radiator based system lead to a room temperature increase of 3.1 K compared to only 0.2 K for the CCA. Thus, due to the potential thermal discomfort the radiator based system would require either the limitation of permitted indoor temperature or a more complex control with occupancy monitoring / prediction. Furthermore, it is shown for the CCA system that integration of an exemplary signal indicating high availability of renewable energies (RE) would have doubled the consumption of the RE during our field test time without compromising thermal comfort.