Model-based investigation on building thermal mass utilization and flexibility enhancement of air conditioning loads

Building air conditioning systems (ACs) can contribute to the stable operation of power grids by participating in peak load shaving programs, but the participants need a fast and accurate zone temperature prediction model, e.g., the detailed room thermal-resistance (RC) model, to improve peak shaving effect and avoid obvious thermal discomfort. However, when applying the detailed room RC model to multi-zone buildings, conventional studies mostly consider the heat transfer among neighboring rooms, which contributes little to the prediction accuracy improvement, but leads to complicated model structure and heavy computation. Thus, a distributed RC model is developed for multi-zone buildings in this study. Compared to conventional models, the proposed model considers the total heat transfer between the building and the air, and ignores the heat transfer among indoor air in neighboring rooms through internal walls with heavy thermal mass, thereby having comparable temperature prediction accuracy, simpler structure, and stronger robustness. Based on the model, the effectiveness of passive pre-cooling strategies in reducing the air conditioning loads during peak periods is investigated. Results indicate that the thermal insulation performance of opaque building envelope is quite important to the flexibility enhancement of air conditioning loads. With an uninsulated building envelope, passive pre-cooling is useless for the peak load shaving. In comparison, well insulated opaque building envelope enables the building thermal mass to be utilized through passive pre-cooling, which leads to the air conditioning loads during peak periods being further reduced by about 12%.