Heat flexibility evaluation and multi-objective optimized control of a low-energy building with district heating

Abstract

Along with the increasing application of the renewable energy in the energy systems, the future energy system will be more stochastic and fluctuated. Therefore, it is of great importance to effectively coordinate the energy supply and demand side considering their different dynamic characteristics. This study analyzes the impact of the integrated energy flexibility from the building mass and the storage tank on the heating system operation for a low-energy building connected to district heating (DH). According to the actual room occupancy and dynamic heat price, the strategy to unlock the energy flexibility is developed and optimized. The detailed thermal performance of the system is simulated by Modelica models. Compared to the reference case, the integrated energy flexibility is helpful to make better use of the low-price heat. Moreover, a variety of quantification indices were developed to evaluate the flexibility and rebound effect. The results show that the fully charged thermal mass of the low-energy building can help maintain the comfort indoor temperature for up to 43 h. Combined with the storage tank, the heat flexibility potential of the case building reaches 78 kWh and saves 1.1 DKK of the daily heat cost with the optimized heating strategy compared to the reference scenario. Moreover, the flexibility factor is improved by shifting the peak heat load to the low-price period.